MAX1636EAP+ ,Low-Voltage, Precision Step-Down Controller for Portable CPU PowerApplicationsTypical Operating CircuitNotebook ComputersSubnotebook ComputersVINDesktop ComputersBus ..
MAX1637EEE ,Miniature / Low-Voltage / Precision Step-Down ControllerELECTRICAL CHARACTERISTICS(Circuit of Figure 1, V = V = 5V, SYNC = V , I = 0mA, T = 0°C to +85°C, u ..
MAX1637EEE+ ,Miniature, Low-Voltage, Precision Step-Down Controllerfeatures a logic-controlled and synchro-MAX1637EEE 40°C to +85°C 16 QSOPnizable, fixed-frequency, p ..
MAX1637EEE+T ,Miniature, Low-Voltage, Precision Step-Down ControllerELECTRICAL CHARACTERISTICS (continued)(Circuit of Figure 1, V = V = 5V, SYNC = V , I = 0mA, T = 0°C ..
MAX1638EAG ,High-Speed Step-Down Controller with Synchronous Rectification for CPU PowerApplicationsPentium Pro™, Pentium II™, PowerPC™, Alpha™,TO VDD MAX1638DHand K6™ SystemsWorkstations ..
MAX1638EAG ,High-Speed Step-Down Controller with Synchronous Rectification for CPU Powerapplications in which' Greater than 90% Efficiency Using N-Channeloutput voltage precision and good ..
MAX4382EEE ,Ultra-Small / Low-Cost / 210MHz / Single-Supply Op Amps with Rail-to-Rail Outputs and DisableMAX4380–MAX438419-2012; Rev 2; 4/03Ultra-Small, Low-Cost, 210MHz, Single-SupplyOp Amps with Rail-to ..
MAX4382EEE+ ,Ultra-Small, Low-Cost, 210MHz, Single-Supply Op Amps with Rail-to-Rail Outputs and DisableELECTRICAL CHARACTERISTICS–Single Supply (V = +5V, V = 0, V = V /2, V = V /2, R = ∞ to V /2, DISABL ..
MAX4382EEE+T ,Ultra-Small, Low-Cost, 210MHz, Single-Supply Op Amps with Rail-to-Rail Outputs and DisableFeaturesThe MAX4380–MAX4384 family of op amps are unity-♦ Low Cost and High Speed:gain-stable devic ..
MAX4382ESD ,Ultra-Small / Low-Cost / 210MHz / Single-Supply Op Amps with Rail-to-Rail Outputs and DisableELECTRICAL CHARACTERISTICS–Single Supply (V = +5V, V = 0, V = V /2, V = V /2, R = ∞ to V /2, DISABL ..
MAX4382ESD+ ,Ultra-Small, Low-Cost, 210MHz, Single-Supply Op Amps with Rail-to-Rail Outputs and DisableMAX4380–MAX438419-2012; Rev 2; 4/03Ultra-Small, Low-Cost, 210MHz, Single-SupplyOp Amps with Rail-to ..
MAX4382EUD ,Ultra-Small / Low-Cost / 210MHz / Single-Supply Op Amps with Rail-to-Rail Outputs and DisableELECTRICAL CHARACTERISTICS–Single Supply (V = +5V, V = 0, V = V /2, V = V /2, R = ∞ to V /2, DISABL ..
MAX1636EAP+
Low-Voltage, Precision Step-Down Controller for Portable CPU Power
General DescriptionThe MAX1636 is a synchronous, buck, switch-mode,
power-supply controller that generates the CPU supply
voltage in battery-powered systems. It achieves ±1%
output voltage accuracy and offers the excellent load-
transient response needed by upcoming generations of
dynamic-clock CPUs.
Up to 95% efficiency is achieved through synchronous
rectification and Maxim’s proprietary Idle Mode™ con-
trol scheme. Efficiency is greater than 80% over a
1000:1 load-current range, extending battery life in sys-
tem-suspend or standby modes. Excellent dynamic
response corrects output load transients caused by the
latest dynamic-clock CPUs within five 300kHz clock
cycles. Strong, 1A, on-board gate drivers ensure fast,
external N-channel MOSFET switching.
The MAX1636 features a logic-controlled and synchro-
nizable, fixed-frequency, pulse-width-modulation (PWM)
operating mode that reduces noise and RF interference
in sensitive mobile communications and pen-entry appli-
cations. Holding SKIPhigh forces fixed-frequency mode
for lowest noise under all load conditions.
For a low-cost version that omits the +5V VL linear-
regulator block and comes in a smaller 16-pin QSOP
package, refer to the MAX1637 data sheet.
ApplicationsNotebook Computers
Subnotebook Computers
Desktop Computers
Bus-Termination Supplies
Features±1% DC Accuracy (Adjustable Mode)Output Overvoltage Crowbar ProtectionOutput Undervoltage ShutdownAdjustable Switching Frequency to 340kHzLow-Dropout OperationIdle Mode Pulse-Skipping Operation1.10V to 5.5V Adjustable Output Voltage2.5V/3.3V Dual-Mode Fixed-Output SettingsInternal Digital Soft-Start1.1V ±1% Reference Output3μA (typ) Shutdown Current Open-Drain Power-Good Output (RESET)20-Pin SSOP Package
MAX1636
Low-Voltage, Precision Step-Down
Controller for Portable CPU PowerSKIP
BSTSHDN
RESET
CSL
CSH
TOP VIEW
PGNDSYNC
REF
OVP
VCCGND
GND
MAX1636
SSOP19-1268; Rev 3; 8/05
Idle Mode is a trademark of Maxim Integrated Products.
Pin Configurationypical Operating Circuit
Ordering InformationMAX1636SHDN
GND
VIN
PGND
VCC
BST
OVP
CSH
CSL
RESETTO μP
SKIP
GND
SYNC
REF
PART MAX1636EAP-40°C to +85°C
TEMP RANGEPIN-PACKAGE20 SSOP
MAX1636EAP+-40°C to +85°C20 SSOP
+Denotes lead-free package.
EVALUATION KIT
AVAILABLE
MAX1636
Low-Voltage, Precision Step-Down
Controller for Portable CPU Power
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS(Circuit of Figure 1, V+ = 15V, SYNC = VL = VCC, IVL= 0mA, IREF= 0mA, TA
= 0°C to +85°C, unless otherwise noted. Typical valuesare 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.
V+ to GND ...............................................................-0.3V to 36V
GND to PGND........................................................................±2V
SHDNto GND..........................................................-0.3V to 36V
LX, BST to GND.......................................................-0.3V to 36V
DH, BST to LX.............................................................-0.3V to 6V
VL, VCC, CSL, CSH, FB, SKIPto GND ...................... -0.3V to 6V
DL to GND....................................................-0.3V to (VL + 0.3V)
REF, RESET, SYNC, CC, OVP to GND......-0.3V to (VCC+ 0.3V)
VL Output Current...............................................................50mA
VL Short Circuit to GND..............................................Momentary
REF Output Current ............................................................20mA
REF Short Circuit to GND .............................................Indefinite
Continuous Power Dissipation (TA= +70°C)
SSOP (derate 8.00mW/°C above +70°C).....................640mW
Operating Temperature Range
MAX1636EAP...................................................-40°C to +85°C
Storage Temperature Range.............................-65°C to +160°C
Junction Temperature......................................................+150°C
Lead Temperature (soldering, 10s).................................+300°C
Gate-driver supply rail
CSH - CSL
Input source for VL regulator
SHDNto full current limit, five levels
FB forced to REF
Positive direction
SHDN= GND, OVP = GND
VCC= 3.3V, output not switching
VCC= 3.3V, VL = 5V
VCC= VL = 5V
Internal chip supply rail
FB tied to VOUT, 0mV < (CSH - CSL) < 80mV, 4.5V
< V+ < 30V (includes line and load regulation)
FB tied to VCC, 0mV < (CSH - CSL) < 80mV, 4.5V
< V+ < 30V (includes line and load regulation)
VCC= 5V, output not switching
FB tied to GND, 0mV < (CSH - CSL) < 80mV, 4.5V
< V+ < 30V (includes line and load regulation)
Negative direction
CONDITIONS203040Idle Mode Switchover Threshold
clks512Soft-Start Ramp Time-5050FB Input Current310Shutdown Supply Current (V+)
1.5Power Consumption2.0
-145 -100-554.25.5Input Voltage Range, VL4.530Input Voltage Range, V+80100120Current-Limit Threshold
VREF3.6VVREF5.5Output Adjustment Range3.155.5Input Voltage Range, VCC1.0901.1001.110Output Voltage, Adj Mode 2.4862.552.614 Output Voltage, Fixed 2.5V Mode3.282 3.366 3.450Output Voltage, Fixed 3.3V Mode
UNITSMINTYPMAXPARAMETER
SMPS CONTROLLER
MAX1636
Low-Voltage, Precision Step-Down
Controller for Portable CPU Power
ELECTRICAL CHARACTERISTICS (continued)(Circuit of Figure 1, V+ = 15V, SYNC = VL = VCC, IVL= 0mA, IREF= 0mA, TA
= 0°C to +85°C, unless otherwise noted. Typical valuesare at TA= +25°C.)
FB to DL delay, 22mV overdrive, CGATE= 2000pF
SHDN= GND, OVP = VCC
FB, with respect to regulation point
VCC= 5V, I(VL) = 0, V+ = 4.5V
(includes PNP base current)
VCC= 5V, I(VL) = 0
Guaranteed by design
SYNC = VCC
SYNC = GND
SYNC = VCC
I(VL) = 0 to 25mA, 5V < V+ < 30V
I(VL) = 0 to 25mA, 6V < V+ < 30V
Rising edge, hysteresis = 25mV
SYNC = GND
REF load = 0 to 50µA
SYNC = GND1501.254 710
kHz240340SYNC Input Frequency Range200SYNC Input Rise/Fall Time200SYNC Input Pulse Width Low
Maximum Duty Factor, Dropout Mode98999660Standby Supply Current (V+)500Regulator Supply Current (V+) 94
270300330kHz4.55.0 5.3
4.75.0 5.3VL Output Voltage3.15VL/ VCCSwitchover Threshold10REF Load Regulation
Hysteresis = 10°C
Rising edge, hysteresis = 25mVV3.453.603.75VL Undervoltage Lockout Threshold
No REF load V1.0901.1001.110REF Output Voltage
VCC= 3.3V to 5.5VmV3REF Line Regulation
Oscillator FrequencySYNC Input Pulse Width High
Maximum Duty Factor
Overvoltage Trip Threshold
Thermal Shutdown Threshold
Overvoltage Fault Propagation Delay
Pin at GND or VCC;SKIP, OVP, SYNC
SHDN, SKIP, OVP, SYNC
SHDN, SKIP, OVP, SYNC
Falling edge (hysteresis = 1%)
From shutdown or power-on-reset state
% of nominal output0.4RESETOutput Voltage Low-110.82.4Logic Input Voltage High
clksCatastrophic Output Undervoltage
Lockout Delay
Logic Input Voltage Low
Logic Input Bias Current
clks32768RESETDelay Time-6 -3RESETTrip Threshold
Catastrophic Output Undervoltage
Lockout Threshold 607080
ISINK= 4mA
+5.5V stress voltage appliedµA1RESET Output Leakage Current
CONDITIONSUNITSMINTYPMAXPARAMETERSHDN= GND or V+µA-33SHDNInput Bias Current
INTERNAL VL REGULATOR AND REFERENCE
OSCILLATOR
OVERVOLTAGE PROTECTION
INPUTS AND OUTPUTS
MAX1636
Low-Voltage, Precision Step-Down
Controller for Portable CPU PowerGate-driver supply rail
Input source for VL regulator
VCC= 3.3V, VL = 5V
VCC= VL = 5V
Internal chip supply rail
FB tied to VOUT, 0mV < (CSH - CSL) < 80mV, 4.5V
< V+ < 30V (includes line and load regulation)
FB tied to VCC, 0mV < (CSH - CSL) < 80mV, 4.5V
< V+ < 30V (includes line and load regulation)
FB tied to GND, 0mV < (CSH - CSL) < 80mV, 4.5V
< V+ < 30V (includes line and load regulation)
CONDITIONS4.25.5Input Voltage Range, VL4.530Input Voltage Range, V+
VREF3.6VVREF5.5Output Adjustment Range3.155.5Input Voltage Range, VCC1.0861.114Output Voltage, Adj Mode 2.4322.635 Output Voltage, Fixed 2.5V Mode3.195 3.497Output Voltage, Fixed 3.3V Mode
UNITSMINTYPMAXPARAMETERHigh or low, DH or DL
DH or DL forced to 2V
CSH = CSL = 5V, V+ = VL = VCC=
GND, either CSH or CSL input
CONDITIONS7Gate-Driver On-Resistance1Gate-Driver Sink/Source Current10Current-Sense Input
Leakage Current
UNITSMINTYPMAXPARAMETER
ELECTRICAL CHARACTERISTICS (continued)(Circuit of Figure 1, V+ = 15V, SYNC = VL = VCC, IVL= 0mA, IREF= 0mA, TA
= 0°C to +85°C, unless otherwise noted. Typical valuesare at TA= +25°C.)
ELECTRICAL CHARACTERISTICS(Circuit of Figure 1, V+ = 15V, SYNC = VL = VCC, IVL= 0mA, IREF= 0mA, TA
=-40°C to +85°C, unless otherwise noted.) (Note 1)VCC= 5V, I(VL) = 0
Regulator Supply Current (V+)VCC= 5V, I(VL) = 0, V+ = 4.5V
(includes PNP base current)
SHDN= GND, OVP = VCCµA60Standby Supply Current (V+)
I(VL) = 0 to 25mA, 6V < V+ < 30VV4.75.3
I(VL) = 0 to 25mA, 5V < V+ < 30VVL Output Voltage
Rising edge, hysteresis = 25mVV3.453.91
VL Undervoltage Lockout
Threshold
VCC= 5V, output not switching
Positive direction
2.070130Current-Limit Threshold
VCC= 3.3V, output not switching1.5Power ConsumptionmW
SMPS CONTROLLER
INTERNAL VL REGULATOR AND REFERENCE
MAX1636
Low-Voltage, Precision Step-Down
Controller for Portable CPU Power
ELECTRICAL CHARACTERISTICS (continued)(Circuit of Figure 1, V+ = 15V, SYNC = VL = VCC, IVL= 0mA, IREF= 0mA, TA
= -40°C to +85°C, unless otherwise noted.) (Note 1)FB, with respect to regulation point
Guaranteed by design
SYNC = GND
SYNC = VCC3.510
Oscillator FrequencySYNC Input Pulse Width High
Overvoltage Trip Threshold
kHz240340SYNC Input Frequency Range200SYNC Input Rise/Fall Time200SYNC Input Pulse Width Low
SHDN, SKIP, OVP, SYNC
SHDN, SKIP, OVP, SYNC
Falling edge (hysteresis = 1%)
% of nominal output0.4RESETOutput Voltage Low0.8
Logic Input Voltage High
kHz
Logic Input Voltage Low-7 -1.5RESETTrip Threshold
Catastrophic Output Undervoltage
Lockout Threshold 6080
ISINK= 4mA
High or low, DH or DLΩ7Gate-Driver On-Resistance
CONDITIONSUNITSMINTYPMAXPARAMETER
OSCILLATOR
OVERVOLTAGE PROTECTION
INPUTS AND OUTPUTS
__________________________________________Typical Operating Characteristics(Circuit of Figure 1, VIN= 7V, TA= +25°C, unless otherwise noted.)
100100m110m10
EFFICIENCY vs. LOAD CURRENT
(3.3V/3A CIRCUIT)MAX1636 TOC01
LOAD CURRENT (A)
EFFICIENCY (%)70
VIN = 22VVIN = 30V
VIN = 7V
VIN = 15V
100100m110m10
EFFICIENCY vs. LOAD CURRENT
(5V/3A CIRCUIT)MAX1636 TOC02
LOAD CURRENT (A)
EFFICIENCY (%)70
VIN = 22V
VIN = 7V
VIN = 15V
VIN = 30V
100100m110m10
EFFICIENCY vs. LOAD CURRENT
(1.8V/1A CIRCUIT)MAX1636 TOC03
LOAD CURRENT (A)
EFFICIENCY (%)70
VIN = 15V
VIN = 7V
VIN = 22V
Note 1:Specifications to -40°C are guaranteed by design and not production tested.
MAX1636 TOC11
FOSC (kHz)
RESET TIME DELAY (ms)
RESET TIME DELAY
vs. OSC FREQUENCYVOUT
50mV/div
LOAD
CURRENT
LOAD-TRANSIENT RESPONSE
(3.3V/3A, PWM MODE)MAX1636 TOC12
100μs/div)
DROPOUT VOLTAGE
vs. LOAD CURRENT
MAX1636 TOC10
LOAD CURRENT (A)
IN
- V
OUT
(mV)
VOUT FORCED TO 4.95V
MAX1636
Low-Voltage, Precision Step-Down
Controller for Portable CPU Power100m110m10
MAX1636 TOC07
LOAD CURRENT (A)
LOAD REGULATION
OUT
(mV)
LOAD REGULATION
vs. LOAD CURRENTPWM MODE
VOUT = 5V
_____________________________Typical Operating Characteristics (continued)(Circuit of Figure 1, VIN= 7V, TA = +25°C, unless otherwise noted.)
100100m110m10
EFFICIENCY vs. LOAD CURRENT
(1.8V/4A CIRCUIT)MAX1636 TOC04
LOAD CURRENT (A)
EFFICIENCY (%)70VIN = 7V
VIN = 22V
VIN = 15V
100100m110m10
EFFICIENCY vs. LOAD CURRENT
(1.8V/7A CIRCUIT)MAX1636 TOC05
LOAD CURRENT (A)
EFFICIENCY (%)70
VIN = 15V
VIN = 7V
VIN = 22V
QUIESCENT SUPPLY CURRENT
vs. INPUT VOLTAGE
MAX1636 TOC06
INPUT VOLTAGE (V)
QUIESCENT SUPPLY CURRENT (mA)
VOUT = 3.3V1015202553035404550
VL LOAD-REGULATION ERROR
vs. VL LOAD CURRENTMAX1636 TOC08
VL LOAD CURRENT (mA)
LOAD REGULATION
V (mV)
REF LOAD-REGULATION ERROR
vs. REF LOAD CURRENT
MAX1636 TOC09
REF LOAD CURRENT (μA)
LOAD REGULATION
V (mV)
MAX1636
Low-Voltage, Precision Step-Down
Controller for Portable CPU Power
_____________________________Typical Operating Characteristics (continued)(Circuit of Figure 1, VIN= 7V, TA = +25°C, unless otherwise noted.)
VOUT
50mV/div
5A LOAD CURRENT
10A
LOAD-TRANSIENT RESPONSE
(1.8V, PWM MODE)MAX1636 TOC13
100μs/div
VOUT
20mV/div
VLX
INDUCTOR
CURRENT
1A
0V
SWITCHING WAVEFORMS
(PWM MODE)MAX1636 TOC14
1μs/div
VOUT
50mV/div
VLX
INDUCTOR
CURRENT
1A
SWITCHING WAVEFORMS
(PFM MODE)MAX1636 TOC15
20μs/div
VOUT = 1.8V
VOUT
1V/div
VSHDN
5V/div
STANDBY AND STARTUP RESPONSE
(VOUT = 1.8V, NO LOAD)MAX1636 TOC17
1ms/div
VOUT
20mV/div
VLX
INDUCTOR
CURRENT4A
SWITCHING WAVEFORMS
(DROPOUT OPERATION)MAX1636 TOC16
5μs/div
VOUT = 5V
VOUT
100mV/div
VDL
INDUCTOR
CURRENT-5A
5V
-10A
OVERVOLTAGE-PROTECTION WAVEFORMS
(VIN SHORTED TO VOUT
THROUGH a 0.5Ω RESISTOR)MAX1636 TOC18
10μs/div
MAX1636
Low-Voltage, Precision Step-Down
Controller for Portable CPU Power
Pin Description
NAMEFUNCTIONCSHCurrent-Sense Input, High SideCSLCurrent-Sense Input, Low Side. Also serves as a feedback input in fixed output modes.
PINRESETTimed Reset Output. Low for at least 100ms after output voltage is valid, then goes high impedance
(open drain).SHDNShutdown Control Input. Puts chip in shutdown or standby mode, depending on OVP (Table 5).SYNCOscillator Frequency Select and Synchronization Input. Tie to VCCfor 300kHz operation; tie to GND for
200kHz operation. REF1.100V Reference Output. Capable of sourcing 50µA for external loads; bypass with a 0.22µF
(min) capacitor.CCCompensation pin. Connect a small capacitor to GND to set the integration time constant. OVPOvervoltage Protection Enable/Disable. Tie to GND to disable OVP; tie to VCCto enable OVP.V+5V VL Linear-Regulator Input. The VL linear regulator automatically shuts off if V+ is shorted to VL. Bypass
V+ to GND with a 0.1µF capacitor close to the IC.VCCMain Supply Voltage Input. Powers the PWM controller, logic, and reference. Input range is +3.15V to
+5.5V. FBFeedback Input. Tie to GND for fixed 3.3V output; tie to VCCfor fixed 2.5V output; tie to resistor divider for
adjustable mode.
9, 10GNDAnalog GroundDLLow-Side Gate-Driver OutputVL5V Linear-Regulator Output. Powers the DL low-side gate driver. Bypass with a 2.2µF (min) capacitor. SKIPLow-Noise Mode Control. Forces fixed-frequency PWM operation when high.LXInductor ConnectionDHHigh-Side Gate-Driver OutputBSTBoost-Capacitor ConnectionPGNDPower Ground
Standard Application CircuitThe basic MAX1636 buck converter (Figure 1) is easily
adapted to meet a wide range of applications with
inputs up to 30V by substituting components from
Table 1. These circuits represent a good set of trade-
offs between cost, size, and efficiency, while staying
within the worst-case specification limits for stress-
related parameters, such as capacitor ripple current.
Do not change the circuits’ switching frequency without
first recalculating component values (particularly induc-
tance value at maximum battery voltage). Adding a
Schottky rectifier across the synchronous rectifier
improves circuit efficiency by approximately 1%. This
rectifier is otherwise not needed because the MOSFET
required typically incorporates a high-speed silicon
diode from drain to source. Use a Schottky rectifier
rated at a DC current equal to at least one-third of the
load current.
MAX1636
Low-Voltage, Precision Step-Down
Controller for Portable CPU Power
Table 1. Component Selection for Standard Applications
COMPONENTLOAD CURRENTInput Voltage
Range7V to 22V7V to 22V7V to 22V4.75V to 30V6V to 30V
Output Voltage
Range1.8V1.8V1.25V to 2V3.3V5V
ApplicationCPU I/OCPUCoreCPUCore
Frequency300kHz300kHz300kHz300kHz300kHz
Q1 High-Side
MOSFET
1/2 Si4902DY or
1/2 MMDF3NO3HD
International Rectifier
IRF7413,
Fairchild NDS8410A,
or Siliconix Si4410DY
International Rectifier
IRF7403 or
Siliconix Si9804DY
International Rectifier
IRF7413,
Fairchild NDS8410A,
or Siliconix Si4410DY
International Rectifier
IRF7413,
Fairchild NDS8410A,
or Siliconix Si4410DY
Q2 Low-Side
MOSFET
1/2 Si4902DY or
1/2 MMDF3NO3HD
International Rectifier
IRF7413,
Fairchild NDS8410A,
or Siliconix Si4410DY
Fairchild FDS6680 or
Siliconix Si4420DY
International Rectifier
IRF7413,
Fairchild NDS8410A,
or Siliconix Si4410DY
International Rectifier
IRF7413,
Fairchild NDS8410A,
or Siliconix Si4410DY
C1 Input
Capacitor
4.7µF, 25V ceramic
Tokin C34Y5U1E475Z
or Marcon/United
Chemicon
THCR40E1E475Z
2 x 10µF, 25V ceramic
Tokin C34Y5U1E106Z
or Marcon/United
Chemicon
THCR50E1E106ZT
4 x 10µF, 25V ceramic
Tokin C34Y5U1E106Z
or Marcon/United
Chemicon
THCR50E1E106ZT
2 x22µF, 35V
AVX
TPSE226M035R0300
Sprague
593D226X0035E2W
2 x 22µF, 35V
AVX
TPSE226M035R0300
Sprague
593D226X0035E2W
C2 Output
Capacitor
220µF, 6.3V tantalum
Sprague
595D227X96R3C2
2 x 470µF,
4V low-ESR
Sprague
594D477X0004R2T
4 x 390µF, 6.3V low-
ESR, Sprague
594D397X06R3R2T,4 x 470µF, 4V
Sprague
594D477X0004R2T
2x 220µF
Sprague 594D
594D227X0010D2T
2x 220µF
Sprague 594D
594D227X0010D2T
R1 Resistor
0.070Ω, 1% (1206)
Dale
WSL-1206-R070F
0.015Ω, 1% (2512)
Dale
WSL-2512-R015F
0.010Ω, 1% (2512)
Dale
WSL-2512-R010F
0.020Ω, 1% (2010)
Dale
WSL-2010-R020F
0.020Ω, 1% (2010)
Dale
WSL-2010-R020F
L1 Inductor15µH
Sumida CD54-150
4.6µH
Panasonic
ETQP1F4R6H,
Sumida
CDRH127-4R7,
Coiltronics
UP2-4R7, or
Coilcraft
DO3316P-472
2.2µH
Panasonic P1F2R0HL,
Sumida
CDRH127-2R4,
Coiltronics
UP4-2R2, or
Coilcraft
DO5022P-222HC
10µH
Sumida
CDRH125-100,
Coiltronics
UP2-100, or
Coilcraft
DO3316-103
10µH
Sumida
CDRH125-100,
Coiltronics
UP2-100, or
Coilcraft
DO3316-103
4A7A (EV KIT)3A3A
IRC(1) 512-992-3377(512) 992-7900
Detailed Description
The MAX1636 is a BiCMOS, switch-mode, power-sup-
ply controller designed primarily for buck-topology reg-
ulators in battery-powered applications where high
efficiency and low quiescent supply current are critical.
Light-load efficiency is enhanced by automatic Idle
Mode operation, a variable-frequency, pulse-skipping
mode that reduces transition and gate-charge losses.
The step-down, power-switching circuit consists of two
N-channel MOSFETs, a rectifier, and an LC output filter.
The output voltage is the average AC voltage at the
switching node, which is regulated by changing the
duty cycle of the MOSFET switches. The gate-drive sig-
nal to the N-channel high-side MOSFET, which must
exceed the battery voltage, is provided by a flying-
capacitor boost circuit that uses a 100nF capacitor
between BST and LX. The MAX1636 contains 10 major
circuit blocks (Figure 2).
The pulse-width-modulation (PWM) controller consists
of a Dual Mode™ feedback network and multiplexer, a
multi-input PWM comparator, high-side and low-side
gate drivers, and logic. The MAX1636 contains fault-
protection circuits that monitor the PWM output for
undervoltage and overvoltage. Bias generator blocks
include the 5V (VL) linear regulator and the 1.1V preci-
sion reference. The PWM uses a 200kHz/300kHz syn-
chronizable oscillator. The circuit blocks are powered
from an internal IC power rail that receives power from
either VL or VCC. The synchronous-switch gate driver is
powered directly from VL, while the high-side-switch
gate driver is powered indirectly from VL via an external
diode-capacitor boost circuit.
MAX1636
Low-Voltage, Precision Step-Down
Controller for Portable CPU Power
(619) 661-6835(81) 7-2070-1174Sanyo
Tokin(408) 432-8020
(847) 390-4373
(1) 408-434-0375
(1) 847-390-4428TDK
Sprague
(847) 956-0666(81) 3-3607-5144Sumida
(603) 224-1961
(714) 373-7939
(408) 988-8000
(1) 714-373-7183Panasonic
(1) 603-224-1430
(1) 408-970-3950Siliconix
(602) 303-5454(1) 602-994-6430Motorola
COMPANY
Central
Semiconductor
Matsuo
Fairchild(408) 721-2181(1) 408-721-1635
(714) 969-2491
(512) 992-7900
(1) 714-960-6492
(1) 512-992-3377IRC
Dale
(310) 322-3331(1) 310-322-3332International
Rectifier (IR)
(605) 668-4131
(847) 639-6400
(561) 241-7876
(1) 847-639-1469Coilcraft
(1) 605-665-1627
(1) 561-241-9339Coiltronics
USA PHONE
(516) 435-1110
(803) 946-0690
FACTORY FAX
(COUNTRY CODE)
(1) 516-435-1824
(1) 803-626-3123AVX
Table 2. Component Suppliers
Figure 1. Standard Application Circuit
MAX1636
0.1μF
POWER INPUT
0.1μF1μF
1nF
CMPSH-3C2
OUTPUT
4.7μF
SHDN
*SEE RECTIFIER CLAMP DIODE SECTION
SKIP
PGND
BST
OVP
VCC
SYNC
CSH
CSL
10k
VCC
GND
GND
RESET
REF
(847) 696-2000(1) 847-696-9278Marcon/United
Chemi-Con
Dual Mode is a trademark of Maxim Integrated Products.
MAX1636
Low-Voltage, Precision Step-Down
Controller for Portable CPU Power
REF
VCC
POWER200kHz
300kHz
OSCPWM
LOGIC
TO VL
INPUT
REF
SHDN
V+ SYNC
DL
PGND
BST
SKIP
VL
CSH
CSL
FB
REF
0.2V
GND
POWER
GOOD
VREF -5%
VREF +7%
VREF -30%
60kHz
LP FILTER
SHUTDOWN
CONTROL
1.1V
REF.
POWER
SWITCHOVER
TIMER
ERROR
INTEGRATOR
RESET
OVP
MAX1636
OVERVOLTAGE
FAULT
UNDER-
VOLTAGE
FAULT
OFF
SLOPE
COMPENSATION
LINEAR
REG.
Figure 2. Functional Diagram
PWM Controller
The heart of the current-mode PWM controller is a
multi-input, open-loop comparator that sums four sig-
nals: the output voltage error signal with respect to the
reference voltage, the current-sense signal, the inte-
grated voltage-feedback signal, and the slope-
compensation ramp (Figure 3).
The PWM controller is a direct-summing type, lacking a
traditional error amplifier and the phase shift associat-
ed with it. This direct-summing configuration approach-
es ideal cycle-by-cycle control over the output voltage
(Figure 4).
When SKIP= low, Idle Mode circuitry automatically
optimizes efficiency throughout the load-current range.
Idle Mode dramatically improves light-load efficiency
MAX1636
Low-Voltage, Precision Step-Down
Controller for Portable CPU Power
LowLightIdle
LOAD
CURRENT
Pulse-skipping,
discontinuous inductor
current
MODEDESCRIPTION
PWM
HighLightPWMConstant-frequency PWM,
continuous inductor current
PWMHighHeavyConstant-frequency PWM,
continuous inductor current
LowHeavyConstant-frequency PWM,
continuous inductor currentSKKIIPP
Table 3. SSKKIIPPPWM Table
SHOOT-
THROUGH
CONTROL
30mV
LEVELSHIFT
OSC
LEVEL
SHIFT
CURRENT
LIMIT
SYNCHRONOUS
RECTIFIER CONTROL
SHDNCK
-100mV
CSH
CSL
REF
BST
VGG
PGND
SLOPE
COMPENSATION
SKIP
COUNTER
DAC
SOFT-START
Figure 3. PWMController Functional Diagram
