MAX1533AETJ+ ,High-Efficiency, 5x Output, Main Power-Supply Controllers for Notebook ComputersApplicationsON3 2 23 LDO52 to 4 Li+ Cells Battery-Powered DevicesFSEL 3 22 DL5Notebook and Subnoteb ..
MAX1533ETJ+T ,High-Efficiency, 5x Output, Main Power-Supply Controllers for Notebook ComputersApplicationsON3 2 23LDO52 to 4 Li+ Cells Battery-Powered DevicesFSEL 3 22 DL5Notebook and Subnotebo ..
MAX1534ETE+T ,High-Efficiency, Triple-Output, Keep-Alive Power Supply for Notebook ComputersFeaturesThe MAX1534 is a high-efficiency, triple-output power♦ One Switching and Two Linear Regulat ..
MAX1535AETJ ,Highly Integrated Level 2 SMBus Battery ChargerApplicationsLDO 2 23 DLONotebook and Subnotebook ComputersACIN 3 22 PGNDTablet PCsREF 4 21 CSIPMAX1 ..
MAX1535BETJ+ ,Highly Integrated Level 2 SMBus Battery ChargersApplications13 THMCSSN 28MAX1535BNotebook and Subnotebook Computers VCSSP 29 12 DDMAX1535CTablet PC ..
MAX1535CETJ+ ,Highly Integrated Level 2 SMBus Battery Chargersfeatures. The maximum♦ 6-Bit Input and Charge-Current Resolutioncurrent drawn from the AC adapter i ..
MAX4172EUA ,Low-Cost / Precision / High-Side Current-Sense Amplifierapplications. The 0V to 32V input' 800kHz Bandwidth [V = 100mV (1C)]SENSEcommon-mode range is indep ..
MAX4172EUA ,Low-Cost / Precision / High-Side Current-Sense AmplifierGeneral Description ________
MAX4172EUA ,Low-Cost / Precision / High-Side Current-Sense AmplifierELECTRICAL CHARACTERISTICS(V+ = +3V to +32V; RS+, RS- = 0V to 32V; T = T to T ; unless otherwise no ..
MAX4172EUA+ ,Low-Cost, Precision, High-Side Current-Sense AmplifierMAX4172 Low-Cost, Precision, High-Side Current-Sense Amplifier
MAX4172EUA+T ,Low-Cost, Precision, High-Side Current-Sense AmplifierElectrical Characteristics(V+ = +3V to +32V; V , V = 0 to 32V; T = T to T ; unless otherwise noted. ..
MAX4172EUA-T ,Low-Cost, Precision, High-Side Current-Sense Amplifierapplications. The 0 to 32V input common-mode ● Minimizes Board Space Requirementsrange is independe ..
MAX1533AETJ+
High-Efficiency, 5x Output, Main Power-Supply Controllers for Notebook Computers
General DescriptionThe MAX1533A/MAX1537A are dual step-down, switch-
mode power-supply (SMPS) controllers with synchro-
nous rectification, intended for main 5V/3.3V power
generation in battery-powered systems. Fixed-frequen-
cy operation with optimal interleaving minimizes input
ripple current from the lowest input voltages up to the
26V maximum input. Optimal 40/60 interleaving allows
the input voltage to go down to 8.3V before duty-cycle
overlap occurs, compared to 180°out-of-phase regula-
tors where the duty-cycle overlap occurs when the
input drops below 10V. Output current sensing pro-
vides accurate current limit using a sense resistor.
Alternatively, power dissipation can be reduced using
lossless inductor current sensing.
Internal 5V and 3.3V linear regulators power the
MAX1533A/MAX1537Aand their gate drivers, as well as
external keep-alive loads, up to a total of 100mA. When
the main PWM regulators are in regulation, automatic
bootstrap switches bypass the internal linear regulators,
providing currents up to 200mA from each linear output.
An additional 5V to 23V adjustable internal 150mA linear
regulator is typically used with a secondary winding to
provide a 12V supply.
The MAX1533A/MAX1537A include on-board power-up
sequencing, a power-good (PGOOD) output, digital
soft-start, and internal soft-shutdown output discharge
that prevents negative voltages on shutdown. The
MAX1533A is available in a 32-pin 5mm x 5mm thin
QFN package, and the MAX1537A is available in a 36-
pin 6mm x 6mm thin QFN package. The exposed back-
side pad improves thermal characteristics for
demanding linear keep-alive applications.
Applications2 to 4 Li+ Cells Battery-Powered Devices
Notebook and Subnotebook Computers
PDAs and Mobile Communicators
FeaturesFixed-Frequency, Current-Mode Control40/60 Optimal InterleavingAccurate Differential Current-Sense InputsInternal 5V and 3.3V Linear Regulators with
100mA Load CapabilityAuxiliary 12V or Adjustable 150mA Linear
Regulator (MAX1537A Only)Dual Mode™Feedback—3.3V/5V Fixed or
Adjustable Output (Dual Mode) Voltages200kHz/300kHz/500kHz Switching FrequencyVersatile Power-Up SequencingAdjustable Overvoltage and Undervoltage
Protection6V to 26V Input Range2V ±0.75% Reference OutputPower-Good OutputSoft-Shutdown5µA (typ) Shutdown Current
MAX1533A/MAX1537A
High-Efficiency, 5x Output, Main Power-Supply
Controllers for Notebook Computers313029282726101112131415
MAX1533A
THIN QFN5mm x 5mmTOP VIEW
ON3
ON5
FSEL
ILIM3
ILIM5
REF
GNDVCC
SHDNDH5BST5LX5INCSH5
CSL5
FB5
LDO5
DL5
PGND
DL3
LDO3
FB3CSL3
OVP
LX3
CSH3
BST3
DH3UVP
PGOOD
PGDL
SKIP
Pin Configurations
Ordering Information
PARTTEMP RANGEPIN-PACKAGE
MAX1533AETJ-40°C to +85°C32 Thin QFN 5mm x 5mm
MAX1533AETJ+-40°C to +85°C32 Thin QFN 5mm x 5mm
MAX1537AETX-40°C to +85°C36 Thin QFN 6mm x 6mm
MAX1537AETX+-40°C to +85°C36 Thin QFN 6mm x 6mm
19-4023; Rev 0; 4/06
Dual Mode is a trademark of Maxim Integrated Products, Inc.Pin Configurations continued at end of data sheet.
+Denotes lead-free package.
MAX1533A/MAX1537A
High-Efficiency, 5x Output, Main Power-Supply
Controllers for Notebook Computers
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS(Circuit of Figure1, VIN = 12V, both SMPS enabled, VCC= 5V, FSEL = REF, SKIP= GND, VILIM_ = VLDO5, VINA = 15V, VLDOA = 12V,
ILDO5= ILDO3= ILDOA= no load, TA
= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.)
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
IN, SHDN, INA, LDOA to GND...............................-0.3V to +30V
GND to PGND.......................................................-0.3V to +0.3V
LDO5, LDO3, VCCto GND.......................................-0.3V to +6V
ILIM3, ILIM5, PGDLY to GND...................................-0.3V to +6V
CSL3, CSH3, CSL5, CSH5 to GND..........................-0.3V to +6V
ON3, ON5, FB3, FB5 to GND ..................................-0.3V to +6V
SKIP, OVP, UVPto GND...........................................-0.3V to +6V
PGOOD, FSEL, ADJA, ONA to GND........................-0.3V to +6V
REF to GND................................................-0.3V to (VCC+ 0.3V)
DL3, DL5 to PGND..................................-0.3V to (VLDO5+ 0.3V)
BST3, BST5 to PGND.............................................-0.3V to +36V
LX3 to BST3..............................................................-6V to +0.3V
DH3 to LX3..............................................-0.3V to (VBST3 + 0.3V)
LX5 to BST5..............................................................-6V to +0.3V
DH5 to LX5..............................................-0.3V to (VBST5 + 0.3V)
LDO3, LDO5 Short Circuit to GND.............................Momentary
REF Short Circuit to GND...........................................Momentary
INA Shunt Current.............................................................+15mA
Continuous Power Dissipation (TA = +70°C)
32-Pin TQFN (derate 21.3mW/°C above +70°C).......1702mW
36-Pin TQFN (derate 26.3mW/°C above +70°C).......2105mW
Operating Temperature Range...........................-40°C to +85°C
Junction Temperature......................................................+150°C
Storage Temperature Range.............................-65°C to +150°C
Lead Temperature (soldering, 10s).................................+300°C
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITS
INPUT SUPPLIES (Note 1)LDO5 in regulation626VIN Input Voltage RangeVININ = LDO5, VOUT5 < 4.43V4.55.5V
VIN Operating Supply CurrentIINLDO5 switched over to CSL51535µA
VIN Standby Supply CurrentIIN(STBY)VIN = 6V to 26V, both SMPS off,
includes ISHDN100170µA
VIN Shutdown Supply CurrentIIN(SHDN)VIN = 6V to 26V, SHDN = GND517µA
Quiescent Power ConsumptionPQ
Both SMPS on, FB3 = FB5 = SKIP = GND,
VCSL3 = 3.5V, VCSL5 = 5.3V, VINA = 15V,
ILDOA = 0, PIN + PCSL3 + PCSL5 + PINA
3.54.5mW
VCC Quiescent Supply CurrentICCBoth SMPS on, FB3 = FB5 = GND,
VCSL3 = 3.5V, VCSL5 = 5.3V1.12.1mA
MAIN SMPS CONTROLLERS3.3V Output Voltage in Fixed
ModeVOUT3VIN = 6V to 26V, SKIP = VCC (Note 2)3.2803.333.380V
5V Output Voltage in Fixed ModeVOUT5VIN = 6V to 26V, SKIP = VCC (Note 2)4.9755.055.125V
Feedback Voltage in Adjustable
ModeVFB_VIN = 6V to 26V, FB3 or FB5,
duty factor = 20% to 80% (Note 2)0.9901.0051.020V
Output-Voltage Adjust RangeEither SMPS1.05.5V
FB3, FB5 Dual-Mode Threshold0.10.2V
Feedback Input Leakage CurrentVFB3 = VFB5 = 1.1V-0.1+0.1µA
DC Load RegulationEither SMPS, SKIP = VCC,
ILOAD = 0 to full load-0.1%
MAX1533A/MAX1537A
High-Efficiency, 5x Output, Main Power-Supply
Controllers for Notebook Computers
ELECTRICAL CHARACTERISTICS (continued)(Circuit of Figure1, VIN = 12V, both SMPS enabled, VCC= 5V, FSEL = REF, SKIP= GND, VILIM_ = VLDO5, VINA = 15V, VLDOA = 12V,
ILDO5= ILDO3= ILDOA= no load, TA
= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITSLine-Regulation ErrorEither SMPS, duty cycle = 10% to 90%1%
FSEL = GND170200230
FSEL = REF270300330Operating Frequency (Note 1)fOSC
FSEL = VCC425500575
kHz
FSEL = GND9193
FSEL = REF9193Maximum Duty Factor (Note 1)DMAX
FSEL = VCC9193
Minimum On-TimetON(MIN)(Note 3)200ns%SMPS3 to SMPS5 Phase ShiftSMPS5 starts after SMPS3144Deg
CURRENT LIMITILIM_ Adjustment Range0.5VREFV
Current-Sense Input RangeCSH_, CSL_05.5V
Current-Sense Input Leakage
CurrentCSH_, VCSH_ = 5.5V-1+1µA
Current-Limit Threshold (Fixed)VLIMIT_VCSH_ - VCSL _ , ILIM_ = VCC707580mV
VILIM_ = 2.00V170200230
VILIM_ = 1.00V91100109Current-Limit Threshold
(Adjustable)VLIMIT_VCSH_ - VCSL_
VILIM_ = 0.50V425058
Current-Limit Threshold
(Negative)VNEGVCSH_ - VCSL_, SKIP = VCC, percent of
current limit-120%
Current-Limit Threshold (Zero
Crossing)VZXVPGND - VLX_, SKIP = GND, ILIM_ = VCC3mV
ILIM_ = VCC101622mV
Idle Mode ThresholdVIDLEVCSH_ - VCSL _ With respect to current-
limit threshold (VLIMIT)20%
ILIM_ Leakage CurrentILIM3 = ILIM5 = GND or VCC-0.1+0.1µA
Soft-Start Ramp TimetSSMeasured from the rising edge of ON_ to
full scale
512/
fOSCs
INTERNAL FIXED LINEAR REGULATORSLDO5 Output VoltageVLDO5ON3 = ON5 = GND, 6V < VIN < 26V,
0 < ILDO5 < 100mA4.804.955.10V
LDO5 Undervoltage-Lockout Fault
ThresholdRising edge, hysteresis = 1%3.754.04.25V
LDO5 Bootstrap Switch ThresholdRising edge of CSL5, hysteresis = 1%4.414.75V
LDO5 Bootstrap Switch
Resistance
LDO5 to CSL5, VCSL5 = 5V,
ILDO5 = 50mA0.753Ω
Idle Mode is a trademark of Maxim Integrated Products, Inc.
MAX1533A/MAX1537A
High-Efficiency, 5x Output, Main Power-Supply
Controllers for Notebook Computers
ELECTRICAL CHARACTERISTICS (continued)(Circuit of Figure1, VIN = 12V, both SMPS enabled, VCC= 5V, FSEL = REF, SKIP= GND, VILIM_ = VLDO5, VINA = 15V, VLDOA = 12V,
ILDO5= ILDO3= ILDOA= no load, TA
= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITSLDO3 Output VoltageVLDO3Standby mode, 6V < VIN < 26V,
0 < ILOAD < 100mA3.203.353.42V
LDO3 Bootstrap Switch ThresholdRising edge of CSL3, hysteresis = 1%2.833.10V
LDO3 Bootstrap Switch
Resistance
LDO3 to CSL3, VCSL3 = 3.2V,
ILDO3 = 50mA13Ω
Short-Circuit CurrentLDO3 = LDO5 = GND,
CSL3 = CSL5 = GND150220mA
Short-Circuit Current (Switched
Over to CSL_)
LDO3 = LDO5 = GND, VCSL3 > 3.1V,
VCSL5 > 4.7V250mA
AUXILIARY LINEAR REGULATOR (MAX1537A ONLY)LDOA Voltage RangeVLDOA523V
INA Voltage RangeVINA624V
LDOA Regulation Threshold,
Internal Feedback
ADJA = GND, 0 < ILDOA < 120mA,
VINA > 13V11.412.012.4V
ADJA Regulation Threshold,
External FeedbackVADJA0 < ILDOA < 120mA, VLDOA > 5.0V and
VINA > VLDOA + 1V1.942.002.06V
ADJA Dual-Mode Threshold0.10.150.2V
ADJA Leakage CurrentVADJA = 2.1V-0.1+0.1µA
LDOA Current LimitVLDOA forced to VINA - 1V, VADJA = 1.9V,
VINA > 6V150mA
Secondary Feedback Regulation
ThresholdVINA - VLDOA0.650.80.95V
DL Duty FactorVINA - VLDOA < 0.7V, pulse width with
respect to switching period33%
INA Quiescent CurrentIINAVINA = 24V, ILDOA = no load50165µA
INA Shunt Sink CurrentVINA = 28V10mA
INA Leakage CurrentIINA(SHDN)VINA = 5V, LDOA disabled30µA
REFERENCE (REF)Reference VoltageVREFVCC = 4.5V to 5.5V, IREF = 01.9852.002.015V
Reference Load RegulationIREF = -10µA to +100µA1.9802.020V
REF Lockout VoltageVREF(UVLO)Rising edge, hysteresis = 350mV1.95V
FAULT DETECTIONOutput Overvoltage Trip
Threshold
OVP = GND, with respect to error-
comparator threshold81115%
Output Overvoltage Fault-
Propagation DelaytOVP50mV overdrive10µs
MAX1533A/MAX1537A
High-Efficiency, 5x Output, Main Power-Supply
Controllers for Notebook Computers
ELECTRICAL CHARACTERISTICS (continued)(Circuit of Figure1, VIN = 12V, both SMPS enabled, VCC= 5V, FSEL = REF, SKIP= GND, VILIM_ = VLDO5, VINA = 15V, VLDOA = 12V,
ILDO5= ILDO3= ILDOA= no load, TA
= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITSOutput Undervoltage-Protection
Trip ThresholdWith respect to error-comparator threshold657075%
Output Undervoltage Fault-
Propagation DelaytUVP50mV overdrive10µs
Output Undervoltage-Protection
Blanking TimetBLANKFrom rising edge of ON_6144/
fOSCs
PGOOD Lower Trip ThresholdWith respect to error-comparator
threshold, hysteresis = 1%-14-10-7.5%
PGOOD Propagation DelaytPGOOD_Falling edge, 50mV overdrive10µs
PGOOD Output Low VoltageISINK = 4mA0.4V
PGOOD Leakage CurrentIPGOOD_High state, PGOOD forced to 5.5V1µA
PGDLY Pullup CurrentPGDLY = GND456µA
PGDLY Pulldown Resistance1025Ω
PGDLY Trip ThresholdREF-
0.2REFREF+
0.2V
Thermal-Shutdown ThresholdTSHDNHysteresis = 15°C+160°C
GATE DRIVERSDH_ Gate-Driver On-ResistanceRDHBST_ - LX_ forced to 5V1.55Ω
DL_, high state1.75DL_ Gate-Driver On-ResistanceRDLDL_, low state0.63Ω
DH_ Gate-Driver Source/Sink
CurrentIDHDH_ forced to 2.5V,
BST_ - LX_ forced to 5V2A
DL_ Gate-Driver Source CurrentIDLDL_ forced to 2.5V1.7A
DL_ Gate-Driver Sink CurrentIDL (SINK)DL_ forced to 2.5V3.3A
DL_ rising35Dead TimetDEADDH_ rising26ns
LX_, BST_ Leakage CurrentVBST_ = VLX_ = 26V<220µA
INPUTS AND OUTPUTSHigh2.4Logic Input VoltageSKIP, hysteresis = 600mVLow0.8V
High0.7 x
VCCFault Enable Logic Input VoltageOVP, UVP, ONA
Low0.4
Logic Input CurrentOVP, UVP, SKIP, ONA-1+1µA
Rising trip level1.101.62.20SHDN Input Trip LevelFalling trip level0.9611.04V
Clear fault level/SMPS off level0.8
Delay start level (REF)1.92.1ON_ Input Voltage
SMPS on level2.4
MAX1533A/MAX1537A
High-Efficiency, 5x Output, Main Power-Supply
Controllers for Notebook Computers
ELECTRICAL CHARACTERISTICS (continued)(Circuit of Figure1, VIN = 12V, both SMPS enabled, VCC= 5V, FSEL = REF, SKIP= GND, VILIM_ = VLDO5, VINA = 15V, VLDOA = 12V,
ILDO5= ILDO3= ILDOA= no load, TA
= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.)
ELECTRICAL CHARACTERISTICS (Circuit of Figure1, VIN = 12V, both SMPS enabled, VCC= 5V, FSEL = REF, SKIP= GND, VILIM_= VLDO5, VINA = 15V, VLDOA = 12V,
ILDO5 = ILDO3 = ILDOA= no load, TA
= -40°C to +85°C, unless otherwise noted.) (Note 4)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITSHighVCC - 0.2
REF1.72.3FSEL Three-Level Input Logic
GND0.4
OVP, UVP, SKIP, ONA, ON3, ON5 = GND
or VCC-1+1
SHDN, 0V or 26V-1+1Input Leakage Current
FSEL = GND or VCC-3+3
CSL_ Discharge-Mode
On-ResistanceRDISCHARGE1025Ω
CSL_ Synchronous-Rectifier
Discharge-Mode Turn-On Level0.20.30.4V
PARAMETERSYMBOLCONDITIONSMINMAXUNITS
INPUT SUPPLIES (Note 1)LDO5 in regulation626VIN Input Voltage RangeVININ = LDO5, VOUT5 < 4.4V4.55.5V
VIN Operating Supply CurrentIINLDO5 switched over to CSL5,
either SMPS on35µA
VIN Standby Supply CurrentIIN(STBY)VIN = 6V to 26V, both SMPS off,
includes ISHDN170µA
VIN Shutdown Supply CurrentIIN(SHDN)VIN = 6V to 26V17µA
Quiescent Power ConsumptionPQ
Both SMPS on, FB3 = FB5 = SKIP = GND,
VCSL3 = 3.5V, VCSL5 = 5.3V, VINA = 15V,
ILDOA = 0, PIN + PCSL3 + PCSL5 + PINA
4.5mW
VCC Quiescent Supply CurrentICCBoth SMPS on, FB3 = FB5 = GND,
VCSL3 = 3.5V, VCSL5 = 5.3V2.5mA
MAIN SMPS CONTROLLERS3.3V Output Voltage in
Fixed ModeVOUT3VIN = 6V to 26V, SKIP = VCC (Note 2)3.283.38V
5V Output Voltage in Fixed ModeVOUT5VIN = 6V to 26V, SKIP = VCC (Note 2)4.9755.125V
Feedback Voltage in
Adjustable ModeVFB3, VFB5VIN = 6V to 26V, FB3 or FB5,
duty factor = 20% to 80% (Note 2)0.9821.018V
Output-Voltage Adjust RangeEither SMPS1.05.5V
FB3, FB5 Adjustable-Mode
Threshold VoltageDual-mode comparator0.10.2V
MAX1533A/MAX1537A
High-Efficiency, 5x Output, Main Power-Supply
Controllers for Notebook Computers
ELECTRICAL CHARACTERISTICS (continued)(Circuit of Figure1, VIN = 12V, both SMPS enabled, VCC= 5V, FSEL = REF, SKIP= GND, VILIM_= VLDO5, VINA = 15V, VLDOA = 12V,
ILDO5 = ILDO3 = ILDOA= no load, TA
= -40°C to +85°C, unless otherwise noted.) (Note 4)
PARAMETERSYMBOLCONDITIONSMINMAXUNITSFSEL = GND170230
FSEL = REF240330Operating Frequency (Note 1)fOSC
FSEL = VCC375575
kHz
FSEL = GND91
FSEL = REF91Maximum Duty Factor (Note 1)DMAX
FSEL = VCC91
Minimum On-TimetON(MIN)250ns
CURRENT LIMITILIM_ Adjustment Range0.5VREFV
Current-Limit Threshold (Fixed)VLIMIT_VCSH_ - VCSL _ , ILIM_ = VCC6783mV
VILIM_ = 2.00V170230
VILIM_ = 1.00V90110Current-Limit Threshold
(Adjustable)VLIMIT_VCSH_ - VCSL _
VILIM_ = 0.50V4060
INTERNAL FIXED LINEAR REGULATORSLDO5 Output VoltageVLDO5ON3 = ON5 = GND, 6V < VIN < 26V,
0 < ILDO5 < 100mA4.85.1V
LDO5 Undervoltage-Lockout
Fault ThresholdRising edge, hysteresis = 1%3.754.30V
LDO3 Output VoltageVLDO3Standby mode, 6V < VIN < 28V,
0 < ILOAD < 100mA3.203.43V
AUXILIARY LINEAR REGULATOR (MAX1537A ONLY)LDOA Voltage RangeVLODA523V
INA Voltage RangeVINA624V
LDOA Regulation Threshold,
Internal Feedback
ADJA = GND, 0 < ILDOA < 120mA,
VINA > 13V11.4012.55V
ADJA Regulation Threshold,
External FeedbackVADJA0 < ILDOA < 120mA, VLDOA > 5.0V and
VINA > VLDOA + 1V1.942.08V
ADJA Dual-Mode ThresholdADJA0.100.25V
Secondary Feedback
Regulation ThresholdVINA - VLDOA0.630.97V
INA Quiescent CurrentIINAVINA = 24V, ILDOA = no load165µA
REFERENCE (REF)Reference VoltageVREFVCC = 4.5V to 5.5V, IREF = 01.972.03V
MAX1533A/MAX1537A
High-Efficiency, 5x Output, Main Power-Supply
Controllers for Notebook Computers
ELECTRICAL CHARACTERISTICS (continued)(Circuit of Figure1, VIN = 12V, both SMPS enabled, VCC= 5V, FSEL = REF, SKIP= GND, VILIM_= VLDO5, VINA = 15V, VLDOA = 12V,
ILDO5 = ILDO3 = ILDOA= no load, TA
= -40°C to +85°C, unless otherwise noted.) (Note 4)
PARAMETERSYMBOLCONDITIONSMINMAXUNITS
FAULT DETECTIONOutput Overvoltage Trip
Threshold
OVP = GND, with respect to error-
comparator threshold+8+15%
Output Undervoltage-Protection
Trip ThresholdWith respect to error-comparator threshold+65+75%
PGOOD Lower Trip ThresholdWith respect to error-comparator threshold,
hysteresis = 1%-14.0-7.0%
PGOOD Output Low VoltageISINK = 4mA0.4V
PGDLY Pulldown Resistance25Ω
PGDLY Trip ThresholdREF-
REF+
0.2V
GATE DRIVERSDH_ Gate-Driver On-ResistanceRDHBST_ - LX_ forced to 5V5Ω
DL_, high state5DL_ Gate-Driver On-ResistanceRDLDL_, low state3Ω
INPUTS AND OUTPUTSHigh2.4Logic Input VoltageSKIP, hysteresis = 600mVLow0.8V
High0.7 x
VCCFault Enable Logic Input VoltageOVP, UVP, ONA
Low0.4
Rising trip level1.12.2SHDN Input Trip LevelFalling trip level0.951.05V
Clear fault level0.8
SMPS off level1.6
Delay start level (REF)1.92.1ON_ Input Voltage
SMPS on level2.4
HighVCC - 0.2
REF1.72.3FSEL Three-Level Input Logic
GND0.4
Note 1:The MAX1533A/MAX1537A cannot operate over all combinations of frequency, input voltage (VIN), and output voltage. For
large input-to-output differentials and high-switching frequency settings, the required on-time may be too short to maintain
the regulation specifications. Under these conditions, a lower operating frequency must be selected. The minimum on-time
must be greater than 150ns, regardless of the selected switching frequency. On-time and off-time specifications are mea-
sured from 50% point to 50% point at the DH_ pin with LX_ = GND, VBST_= 5V, and a 250pF capacitor connected from DH_
to LX_. Actual in-circuit times may differ due to MOSFET switching speeds.
Note 2:When the inductor is in continuous conduction, the output voltage has a DC regulation level lower than the error-comparator
threshold by 50% of the ripple. In discontinuous conduction (SKIP= GND, light load), the output voltage has a DC regula-
tion level higher than the trip level by approximately 1% due to slope compensation.
Note 3:Specifications are guaranteed by design, not production tested.
Note 4:Specifications to -40°C are guaranteed by design, not production tested.
MAX1533A/MAX1537A
High-Efficiency, 5x Output, Main Power-Supply
Controllers for Notebook Computers
PWM5 EFFICIENCY vs. LOAD CURRENT
(VOUT5 = 5.0V)MAX1533 toc01
LOAD CURRENT (A)
EFFICIENCY (%)0.1
VIN = 20V
VIN = 12V
VIN = 7V
SKIP = GND
SKIP = VCC
5V OUTPUT VOLTAGE (OUT5)
vs. LOAD CURRENTMAX1533/37 toc02
LOAD CURRENT (A)
OUTPUT VOLTAGE (V)231
SKIP = GND
SKIP = VCC
5V OUTPUT VOLTAGE (OUT5)
vs. INPUT VOLTAGEMAX1533/37 toc03
INPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)152010
SKIP = GND
SKIP = VCC
NO LOAD
PWM3 EFFICIENCY vs. LOAD CURRENT
(VOUT3 = 3.3V)MAX1533/37 toc04
LOAD CURRENT (A)
EFFICIENCY (%)0.1
VIN = 20V
VIN = 12V
VIN = 5V
SKIP = GND
SKIP = VCC
3.3V OUTPUT VOLTAGE (OUT3)
vs. LOAD CURRENTMAX1533/37 toc05
LOAD CURRENT (A)
OUTPUT VOLTAGE (V)231
SKIP = GND
SKIP = VCC
3.3V OUTPUT VOLTAGE (OUT3)
vs. INPUT VOLTAGEMAX1533/37 toc06
INPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)152010
SKIP = GND
SKIP = VCC
NO LOAD
NO-LOAD SUPPLY CURRENT
vs. INPUT VOLTAGE (FULLY ENABLED)MAX1533/37 toc07
INPUT VOLTAGE (V)
SUPPLY CURRENT (mA)15201030
SKIP = GND
SKIP = VCC
ON3 = ON5 = VCC
0.22mA (VIN = 12V)
NO-LOAD SUPPLY CURRENT
vs. INPUT VOLTAGE (STANDBY MODE)MAX1533/37 toc08
INPUT VOLTAGE (V)
STANDBY SUPPLY CURRENT (mA)152010
ON3 = ON5 = GND
SHUTDOWN SUPPLY CURRENT
vs. INPUT VOLTAGEMAX1533/37 toc09
INPUT VOLTAGE (V)
SHUTDOWN SUPPLY CURRENT (15201030
SHDN = GND
Typical Operating Characteristics(MAX1537A circuit of Figure1, VIN = 12V, LDO5 = VCC= 5V, SKIP= GND, FSEL = REF, TA = +25°C, unless otherwise noted.)
MAX1533A/MAX1537A
High-Efficiency, 5x Output, Main Power-Supply
Controllers for Notebook Computers
Typical Operating Characteristics (continued)(MAX1537A circuit of Figure 1, VIN = 12V, LDO5 = VCC= 5V, SKIP= GND, FSEL = REF, TA = +25°C, unless otherwise noted.)
IDLE-MODE CURRENT
vs. INPUT VOLTAGEMAX1533/37 toc10
INPUT VOLTAGE (V)
PEAK CURRENT (A)152010
DUTY CYCLE
LIMITED
5V OUTPUT
2.0V REFERENCE LOAD REGULATIONMAX1533 toc11
REF LOAD CURRENT (μA)
REF VOLTAGE (V)6002040
LINEAR-REGULATOR
LOAD REGULATION
MAX1533/37 toc12
LDO LOAD CURRENT (mA)
LDO DEVIATION VOLTAGE (mV)
LDO3
LDO5
VIN = 6V
ON3 = ON5 = GND
AUXILIARY LINEAR-REGULATOR
LOAD REGULATIONMAX1533/37 toc13
LDOA LOAD CURRENT (mA)
AUX LDO VOLTAGE (V)
INTERLEAVED OPERATION
MAX1533/37 toc14
2.0μs/div
12V
12V
3.3V
A. LX5, 10V/div
B. 5V OUTPUT, 100mV/div
C. PWM5 INDUCTOR CURRENT, 5A/div
D. LX3, 10V/div
E. 3.3V OUTPUT, 100mV/div
F. PWM3 INDUCTOR CURRENT, 5A/div
LINEAR-REGULATOR
STARTUP WAVEFORMSMAX1533/37 toc15
400μs/div
B. LDO5, 2V/div
C. LDO3, 2V/div
D. REF, 2V/div
100Ω LOAD ON LDO5 AND LDO3
A. SHDN, 5V/div
MAX1533A/MAX1537A
High-Efficiency, 5x Output, Main Power-Supply
Controllers for Notebook Computers
DELAYED STARTUP WAVEFORM
(LIGHT LOAD)MAX1533/37 toc16
2ms/div
3.3VA
3.3V
A. ON5, 5V/div
B. 5V OUTPUT, 2V/div
C. 3.3V OUPUT, 2V/div
D. PGOOD, 2V/div
100Ω LOAD ON OUT5 AND OUT3, ON3 = REF
STARTUP WAVEFORM (HEAVY LOAD)MAX1533/37 toc17
400μs/div
3.3V
2.5A
A. ON5, 5V/div
B. 5V OUTPUT, 2V/div
C. INDUCTOR CURRENT, 5A/div
D. LDO5, 1V/div
E. DL5, 5V/div
1.0Ω LOAD
SHUTDOWN WAVEFORM (NO LOAD)MAX1533/37 toc18
2ms/div
3.3V
D. 3.3V OUTPUT, 5V/div
E. DL3, 5V/div
F. PGOOD, 5V/div
B. 5V OUTPUT, 5V/div
C. DL5, 5V/div
A. SHDN, 5V/div
ON3 = ON5 = VCC, OVP = GND
SHUTDOWN WAVEFORM (1Ω LOAD)MAX1533/37 toc19
100μs/div
B. LDO5, 2V/div
C. 5V OUTPUT, 2V/div
D. INDUCTOR CURRENT, 5A/div
E. DL5, 5V/div
ON3 = ON5 = VCC, OVP = GND
A. SHDN, 5V/div
5V OUTPUT LOAD TRANSIENT
(FORCED-PWM)MAX1533/37 toc20
40μs/div
12V
B. VOUT5 = 5.0V, 100mV/div
C. INDUCTOR CURRENT, 5A/div
D. LX5, 10V/div
A. IOUT5 = 0.2A TO 4A, 5A/div
SKIP = VCC
3.3V OUTPUT LOAD TRANSIENT
(FORCED-PWM)MAX1533/37 toc21
40μs/divA
3.3V
12V
B. VOUT3 = 3.3V, 100mV/div
C. INDUCTOR CURRENT, 5A/div
D. LX3, 10V/div
A. IOUT3 = 0.2A TO 4A, 5A/div
SKIP = VCC
Typical Operating Characteristics (continued)(MAX1537A circuit of Figure 1, VIN = 12V, LDO5 = VCC= 5V, SKIP= GND, FSEL = REF, TA = +25°C, unless otherwise noted.)
MAX1533A/MAX1537A
High-Efficiency, 5x Output, Main Power-Supply
Controllers for Notebook Computers
3.3V OUTPUT LOAD TRANSIENT
(PULSE SKIPPING)MAX1533/37 toc22
40μs/divA
3.3V
12V
B. VOUT3 = 3.3V, 100mV/div
C. INDUCTOR CURRENT, 5A/div
D. LX3, 10V/div
A. IOUT3 = 0.2A TO 4A, 5A/div
SKIP = GND
OUTPUT OVERLOAD
(UVP ENABLED)MAX1533/37 toc23
4μs/div
3.3V
12V
B. 3.3V OUTPUT, 3.3V/div
C. LOAD (0 TO 30A), 20A/div
A. PGOOD2, 5V/div
30A
D. INDUCTOR CURRENT, 10A/div
E. LX3, 20V/div
LDO5 LOAD TRANSIENTMAX1533/37 toc24
20μs/div
100mA
5.0V
4.95V
B. ILDO5 = 1mA TO 100mA, 100mA/div
C. LDO5, 50m/div
ON3 = ON5 = GND
A. CONTROL SIGNAL, 5V/div
LDO5 LINE TRANSIENTMAX1533/37 toc25
20μs/div
20V
15V
4.95V
B. LDO5 OUTPUT VOLTAGE, 50mV/div
A. INPUT VOLTAGE (VIN = 7V TO 20V), 5V/div
10V
5.05V
5.00V
ON3 = ON5 = GND, ILDO5 = 20mA
AUXILIARY LINEAR-REGULATOR
LOAD TRANSIENTMAX1533/37 toc26
100μs/div
120mAA
10mA
11.90V
B. INA, 1V/div
A. ILDOA = 10mA TO 100mA, 100mA/div
14V
13V
11.96V
C. LDOA, 50mV/div
INA = VOLTAGE GENERATED BY SECONDARY
TRANSFORMER WINDING
Typical Operating Characteristics (continued)(MAX1537A circuit of Figure 1, VIN = 12V, LDO5 = VCC= 5V, SKIP= GND, FSEL = REF, TA = +25°C, unless otherwise noted.)
MAX1533A/MAX1537A
High-Efficiency, 5x Output, Main Power-Supply
Controllers for Notebook Computers
Pin Description
PIN
MAX1533AMAX1537ANAMEFUNCTION1ADJA
Auxiliary Feedback Input. Connect a resistive voltage-divider from LDOA to analog
ground to adjust the auxiliary linear-regulator output voltage. ADJA regulates at 2V.
Connect ADJA to GND for nominal 12V output using internal feedback.2ON5
5V SMPS Enable Input. The 5V SMPS is enabled if ON5 is greater than the SMPS on
level and disabled if ON5 is less than the SMPS off level. If ON5 is connected to REF,
the 5V SMPS starts after the 3.3V SMPS reaches regulation (delay start). Drive ON5
below the clear fault level to reset the fault latches.3ON3
3.3V SMPS Enable Input. The 3.3V SMPS is enabled if ON3 is greater than the SMPS
on level and disabled if ON3 is less than the SMPS off level. If ON3 is connected to
REF, the 3.3V SMPS starts after the 5V SMPS reaches regulation (delay start). Drive
ON3 below the clear fault level to reset the fault latches.4ONA
LDOA Enable Input. When ONA is low, LDOA is high impedance and the secondary
winding control is off. When ONA is high, LDOA is on. Connect to LDO3, LDO5,
CSL3, CSL5, or other output for desired automatic startup sequencing.5FSEL
Frequency-Select Input. This three-level logic input sets the controller’s switching
frequency. Connect to GND, REF, or VCC to select the following typical switching
frequencies:
VCC = 500kHz, REF = 300kHz, GND = 200kHz6ILIM3
3.3V SMPS Peak Current-Limit Threshold Adjustment. The current-limit threshold
defaults to 75mV if ILIM3 is connected to VCC. In adjustable mode, the current-limit
threshold across CSH3 and CSL3 is precisely 1/10 the voltage seen at ILIM3 over a
500mV to 2.0V range. The logic threshold for switchover to the 75mV default value is
approximately VCC - 1V.7ILIM5
5V S M P S P eak C ur r ent- Li m i t Thr eshol d . The cur r ent- l i m i t thr eshol d d efaul ts to 75m V i f
ILIM 5 i s connected to V C C . In ad j ustab l e m od e, the cur r ent- l i m i t thr eshol d acr oss C S H 5
and C S L5 i s p r eci sel y 1/10th the vol tag e seen at ILIM 5 over a 500m V to 2.0V r ang e. Theog i c thr eshol d for sw i tchover to the 75m V d efaul t val ue i s ap p r oxi m atel y V C C - 1V .8REF
2.0V Reference Voltage Output. Bypass REF to analog ground with a 0.1µF or greater
ceramic capacitor. The reference can source up to 100µA for external loads. Loading
REF degrades output-voltage accuracy according to the REF load-regulation error.
The reference shuts down when SHDN is low.9GNDAnalog Ground. Connect the backside pad to GND.
810VCC
Analog Supply Input. Connect to the system supply voltage (+4.5V to +5.5V) through
a series 20Ω resistor. Bypass VCC to analog ground with a 1µF or greater ceramic
capacitor.11PGDLY
Power-Good One-Shot Delay. Place a timing capacitor on PGDLY to delay PGOOD
going high. PGDLY has a 5µA pullup current and a 10Ω pulldown. The pulldown is
activated when power is not good. When power is good, the pulldown is shut off and
the 5µA pullup is activated. When PGDLY crosses REF, PGOOD is enabled.
MAX1533A/MAX1537A
High-Efficiency, 5x Output, Main Power-Supply
Controllers for Notebook Computers
Pin Description (continued)
PIN
MAX1533AMAX1537ANAMEFUNCTION12PGOOD
Open-Drain Power-Good Output. PGOOD is low if either output is more than 10%
(typ) below the normal regulation point, during soft-start, and in shutdown. PGOOD is
delayed on the rising edge by the PGDLY one-shot timer. PGOOD becomes high
impedance when both SMPS outputs are in regulation.13UVP
Undervoltage Fault-Protection Control. Connect UVP to GND to select the default
overvoltage threshold of 70% of nominal. Connect to VCC to disable undervoltage
protection and clear the undervoltage fault latch.14DH3High-Side Gate-Driver Output for 3.3V SMPS. DH3 swings from LX3 to BST3.15BST3
Boost Flying-Capacitor Connection for 3.3V SMPS. Connect to an external capacitor
and diode as shown in Figure 6. An optional resistor in series with BST3 allows the
DH3 pullup current to be adjusted.16LX3Inductor Connection for 3.3V SMPS. Connect LX3 to the switched side of the
inductor. LX3 serves as the lower supply rail for the DH3 high-side gate driver.17OVP
Overvoltage Fault-Protection Control. Connect OVP to GND to select the default
overvoltage threshold of +11% above nominal. Connect to VCC to disable
overvoltage protection and clear the overvoltage fault latch.18CSH3Positive Current-Sense Input for 3.3V SMPS. Connect to the positive terminal of the
current-sense element. Figure 9 describes two different current-sensing options.19CSL3
Negative Current-Sense Input for 3.3V SMPS. Connect to the negative terminal of the
current-sense element. Figure 9 describes two different current-sensing options.
CSL3 also serves as the bootstrap input for LDO3.20FB3Feedback Input for 3.3V SMPS. Connect to GND for fixed 3.3V output. In adjustable
mode, FB3 regulates to 1V.21LDO3
3.3V Internal Linear-Regulator Output. Bypass with 2.2µF (min) (1µF/20mA). Provides
100mA (min). Power is taken from LDO5. If CSL3 is greater than 3V, the linear
regulator shuts down and LDO3 connects to CSL3 through a 1Ω switch rated for
loads up to 200mA.22DL3Low-Side Gate-Driver Output for 3.3V SMPS. DL3 swings from PGND to LDO5.23PGNDPower Ground24DL5Low-Side Gate-Driver Output for 5V SMPS. DL5 swings from PGND to LDO5.25LDO5
5V Internal Linear-Regulator Output. Bypass with 2.2µF (min) (1µF/20mA). Provides
power for the DL_ low-side gate drivers, the DH_ high-side drivers through the BST
diodes, the PWM controller, logic, and reference through the VCC pin, as well as the
LDO3 internal 3.3V linear regulator. Provides 100mA (min) for external loads (+25mA
for gate drivers). If CSL5 is greater than 4.5V, the linear regulator shuts down and
LDO5 connects to CSL5 through a 0.75Ω switch rated for loads up to 200mA.26FB5Feedback Input for 5V SMPS. Connect to GND for fixed 5V output. In adjustable
mode, FB5 regulates to 1V.
MAX1533A/MAX1537A
High-Efficiency, 5x Output, Main Power-Supply
Controllers for Notebook Computers
Pin Description (continued)
PIN
MAX1533AMAX1537ANAMEFUNCTION27CSL5
Negative Current-Sense Input for 5V SMPS. Connect to the negative terminal of the
current-sense element. Figure 9 describes two different current-sensing options.
CSL5 also serves as the bootstrap input for LDO5.28CSH5Positive Current-Sense Input for 5V SMPS. Connect to the positive terminal of the
current-sense element. Figure 9 describes two different current-sensing options.29INInput of the Startup Circuitry and the LDO5 Internal 5V Linear Regulator. Bypass to
PGND with 0.22µF close to the IC.30LX5Inductor Connection for 5V SMPS. Connect LX5 to the switched side of the inductor.
LX5 serves as the lower supply rail for the DH5 high-side gate driver.31BST5
Boost Flying-Capacitor Connection for 5V SMPS. Connect to an external capacitor
and diode as shown in Figure 6. An optional resistor in series with BST5 allows the
DH5 pullup current to be adjusted.32DH5High-Side Gate-Driver Output for 5V SMPS. DH5 swings from LX5 to BST5.33SKIPPulse-Skipping Control Input. Connect to VCC for low-noise forced-PWM mode.
Connect to GND for high-efficiency pulse-skipping mode at light loads.34SHDN
Shutdown Control Input. The device enters its 5µA supply-current shutdown mode if
VSHDN is less than the SHDN input falling-edge trip level and does not restart until
VSHDN is greater than the SHDN input rising-edge trip level. Connect SHDN to VIN for
automatic startup. SHDN can be connected to VIN through a resistive voltage-divider
to implement a programmable undervoltage lockout.35INASupply Voltage Input for the Auxiliary LDOA Linear Regulator. INA is clamped with an
internal shunt to 26V.36LDOA
Adjustable (12V Nominal) 150mA Auxiliary Linear-Regulator Output. Input supply
comes from INA. Bypass LDOA to GND with 2.2µF (min) (1µF/20mA). Secondary
feedback threshold is set at INA - LDOA = 0.8V, and triggers the DL5 on the 5V
SMPS only. ONA high enables regulator output and secondary regulation. PGOOD is
not affected by the state of LDOA.
MAX1533A/MAX1537A
High-Efficiency, 5x Output, Main Power-Supply
Controllers for Notebook Computers
COMPONENT5A/300kHz5A/500kHzInput VoltageVIN = 7V to 24VVIN = 7V to 24V
CIN_, Input Capacitor(2) 10µF, 25V
Taiyo Yuden TMK432BJ106KM
(2) 10µF, 25V
Taiyo Yuden TMK432BJ106KM
COUT5, Output Capacitor150µF, 6.3V, 40mΩ, low-ESR capacitor
Sanyo 6TPB150ML
150µF, 6.3V, 40mΩ, low-ESR capacitor
Sanyo 6TPB150ML
COUT3, Output Capacitor220µF, 4V, 40mΩ, low-ESR capacitor
Sanyo 4TPB220ML
220µF, 4V, 40mΩ, low-ESR capacitor
Sanyo 4TPB220ML
NH_ High-Side MOSFETFairchild Semiconductor FDS6612A
International Rectifier IRF7807V
Fairchild Semiconductor FDS6612A
International Rectifier IRF7807V
NL_ Low-Side MOSFETFairchild Semiconductor FDS6670S
International Rectifier IRF7807VD1
Fairchild Semiconductor FDS6670S
International Rectifier IRF7807VD1
DL_ Schottky Rectifier
(if needed)
2A, 30V, 0.45Vf
Nihon EC21QS03L
2A, 30V, 0.45Vf
Nihon EC21QS03L
Inductor/TransformerT1 = 6.8µH, 1:2 turns Sumida 4749-T132
L1 = 5.8µH, 8.6A Sumida CDRH127-5R8NC
3.9µH
Sumida CDRH124-3R9NC
RCS
10mΩ ±1%, 0.5W resistor
IRC LR2010-01-R010F or
Dale WSL-2010-R010F
10mΩ ±1%, 0.5W resistor
IRC LR2010-01-R010F or
Dale WSL-2010-R010F
SUPPLIERWEBSITEAVXwww.avx.com
Central Semiconductorwww.centralsemi.com
Coilcraftwww.coilcraft.com
Coiltronicswww.coiltronics.com
Fairchild Semiconductorwww.fairchildsemi.com
International Rectifierwww.irf.com
Kemetwww.kemet.com
Detailed DescriptionThe MAX1533A/MAX1537A standard application circuit
(Figure1) generates the 5V/5A and 3.3V/5A typical of the
main supplies in a notebook computer. The input supply
range is 7V to 24V. See Table1 for component selections
and Table2 for component manufacturers.
The MAX1533A/MAX1537A contain two interleaved
fixed-frequency step-down controllers designed for low-
voltage power supplies. The optimal interleaved archi-
tecture guarantees out-of-phase operation, reducing the
input capacitor ripple. Two internal LDOs generate
the keep-alive 5V and 3.3V power. The MAX1537A has
an auxiliary LDO that can be configured to the preset
Fixed Linear Regulators (LDO5 and LDO3)Two internal linear regulators produce preset 5V (LDO5)
and 3.3V (LDO3) low-power outputs. LDO5 powers
LDO3, the gate drivers for the external MOSFETs, and
provides the bias supply (VCC) required for the SMPS
analog control, reference, and logic blocks. LDO5
supplies at least 100mA for external and internal loads,
including the MOSFET gate drive, which typically varies
from 5mA to 50mA, depending on the switching frequen-
cy and external MOSFETs selected. LDO3 also supplies
at least 100mA for external loads. Bypass LDO5 and
LDO3 with a 2.2µF or greater output capacitor, using an
additional 1.0µF per 20mA of internal and external load.
Table1. Component Selection for Standard Applications
Table2. Component Suppliers
SUPPLIERWEBSITEPanasonicwww.panasonic.com/industrial
Sanyowww.semiconductor-sanyo.com
Sumidawww.sumida.com
Taiyo Yudenwww.t-yuden.com
TDKwww.component.tdk.com
TOKOwww.tokoam.com
Vishay (Dale, Siliconix)www.vishay.com
MAX1533A/MAX1537A
High-Efficiency, 5x Output, Main Power-Supply
Controllers for Notebook Computers60.4kΩ
100kΩR5
60.4kΩ
LDO5
DH3
BST3
DL3
LX3
CSH3
ILIM5
CBST
0.1μF
NH2
DL2
RCS2
10mΩ
COUT2
150μF
40mΩ
REF (300kHz)
CONNECT
TO LDO5
POWER-GOOD
3.3V LDO
OUTPUT
NL2
CBST
0.1μF
NH1
NL1
RCS1
10mΩ
COUT1
220μF
40mΩ
DL1L1
5.8μH
DBSTDBST
10μF
5V LDO
OUTPUT
3.3V PWM
OUTPUT
CREF
0.22μF
INPUT (VIN)
SEE TABLE 1 FOR COMPONENT SPECIFICATIONS
SHDN
FB3
OVP
POWER GROUND
ANALOG GROUND
MAX1533A
MAX1537A
REF
CIN
(2) 10μFOFF
12V LDO
OUTPUT
MAX1537A ONLYON3
ON5
INA
ONA
100kΩ
BST5
LX5
DL5
PGND
GND
CSH5
CSL5
FB5
UVP
SKIP
DH5
ILIM3
CSL3OFF
SECONDARY
OUTPUTOFF
22μF
5V PWM
OUTPUT
SECONDARY
OUTPUT
1:2 TURNS
LP = 6.8μH
FSEL
VCC
PGOOD
PGDLY
20ΩC2
1μFR8
100kΩ
LDO3
10μF
10μF
LDOA
ADJA
OPEN
MAX1533A/MAX1537A
High-Efficiency, 5x Output, Main Power-Supply
Controllers for Notebook Computers
SMPS to LDO Bootstrap SwitchoverWhen the 5V main output voltage is above the LDO5
bootstrap-switchover threshold, an internal 0.75Ω(typ)
p-channel MOSFET shorts CSL5 to LDO5 while simulta-
neously shutting down the LDO5 linear regulator.
Similarly, when the 3.3V main output voltage is above
the LDO3 bootstrap-switchover threshold, an internal(typ) p-channel MOSFET shorts CSL3 to LDO3 while
simultaneously shutting down the LDO3 linear regula-
tor. These actions bootstrap the device, powering the
internal circuitry and external loads from the output
SMPS voltages, rather than through linear regulators
from the battery. Bootstrapping reduces power dissipa-
tion due to gate charge and quiescent losses by pro-
viding power from a 90%-efficient switch-mode source,
rather than from a much-less-efficient linear regulator.
The output current limit increases to 200mA when the
LDO_ outputs are switched over.
SMPS 5V Bias Supply (LDO5 and VCC)The A switch-mode power supplies (SMPS) require a
5V bias supply in addition to the high-power input sup-
ply (battery or AC adapter). This 5V bias supply is gen-
erated by the MAX1533A/MAX1537As’ internal 5V linear
regulator (LDO5). This bootstrapped LDO allows the
MAX1533A/MAX1537A to power-up independently. The
gate-driver input supply is connected to the fixed 5V
linear-regulator output (LDO5). Therefore, the 5V LDO
supply must provide VCC(PWM controller) and the
gate-drive power, so the maximum supply current
required is:
IBIAS= ICC+ fSW(QG(LOW)+ QG(HIGH))
= 5mA to 50mA (typ)
where ICCis 1mA (typ), fSWis the switching frequency,
and QG(LOW)and QG(HIGH)are the MOSFET data
sheet’s total gate-charge specification limits at VGS= 5V.
Reference (REF)The 2V reference is accurate to ±1% over temperature
and load, making REF useful as a precision system ref-
erence. Bypass REF to GND with a 0.22µF or greater
ceramic capacitor. The reference sources up to 100µA
and sinks 10µA to support external loads. If highly
accurate specifications (±0.5%) are required for the
main SMPS output voltages, the reference should not
be loaded. Loading the reference reduces the LDO5,
LDO3, OUT5, and OUT3 output voltages slightly
because of the reference load-regulation error.
System Enable/Shutdown (SHDN)Drive SHDNbelow the precise SHDNinput falling-edge
trip level to place the MAX1533A/MAX1537A in their
low-power shutdown state. The MAX1533A/MAX1537A
consume only 5µA of quiescent current while in shut-
down mode. When shutdown mode activates, the refer-
ence turns off, making the threshold to exit shutdown
less accurate. To guarantee startup, drive SHDNabove
2.2V (SHDNinput rising-edge trip level). For automatic
shutdown and startup, connect SHDNto VIN. The accu-
rate 1V falling-edge threshold on SHDNcan be used to
detect a specific input-voltage level and shut the
device down. Once in shutdown, the 1.6V rising-edge
threshold activates, providing sufficient hysteresis for
most applications.
SMPS Detailed
Description
SMPS POR, UVLO, and Soft-StartPower-on reset (POR) occurs when VCCrises above
approximately 1V, resetting the undervoltage, overvolt-
age, and thermal-shutdown fault latches. The POR cir-
cuit also ensures that the low-side drivers are pulled
low if OVP is disabled (OVP= VCC), or driven high if
OVP is enabled (OVP= GND) until the SMPS con-
trollers are activated.
The VCCinput undervoltage-lockout (UVLO) circuitry
inhibits switching if the 5V bias supply (LDO5) is below
the 4V input UVLO threshold. Once the 5V bias supply
(LDO5) rises above this input UVLO threshold and the
controllers are enabled, the SMPS controllers start
switching and the output voltages begin to ramp up
using soft-start.
The internal digital soft-start gradually increases the
internal current-limit level during startup to reduce the
input surge currents. The MAX1533A/MAX1537A divide
the soft-start period into five phases. During the first
phase, each controller limits its current limit to only 20%
of its full current limit. If the output does not reach regu-
lation within 128 clock cycles (1/fOSC), soft-start enters
the second phase and the current limit is increased by
another 20%. This process repeats until the maximum
current limit is reached after 512 clock cycles (1/fOSC)
or when the output reaches the nominal regulation volt-
age, whichever occurs first (see the startup waveforms
in the Typical Operating Characteristics).
MAX1533A/MAX1537A
High-Efficiency, 5x Output, Main Power-Supply
Controllers for Notebook ComputersVCC
REF
FB3
2.0V
REF
DH5
BST5
LX5
LDO5
DL5
PWM5
CONTROLLER
(FIGURE 3)DH3
BST3
DL3
LDO5
LX3
PWM3
CONTROLLER
(FIGURE 3)
PGND
DECODE
(FIGURE 5)
ON3
FSEL
FB DECODE
(FIGURE 5)FB5
ON5
ILIM5
CSH5
CSL5
ILIM3
CSH3
CSL3
OVP
PGOOD
POWER-GOOD AND
FAULT PROTECTION
(FIGURE 7)
INTERNAL
AUL
ADJA
LDOA
INA
ONA
SKIP
UVP
5V LINEAR
REGULATOR
3.3V LINEAR
REGULATORLDO5
PGDLYMAX1537A
AUXILIARY
LINEAR
REGULATOR
(FIGURE 8)
GND
LDO3
LDO BYPASS
CIRCUITRY
LDO BYPASS
CIRCUITRYOSC
SHDN
SECONDAR
FEEDBACK
MAX1533A/MAX1537A
