MAX1710 ,High-Speed, Digitally Adjusted Step-Down Controllers for Notebook CPUsFeaturesThe MAX1710/MAX1711 step-down controllers are♦ Ultra-High Efficiency intended for core CPU ..
MAX17101ETJ+ ,Dual Quick-PWM, Step-Down Controller with Low-Power LDO, RTC RegulatorApplications28 13 PGOOD1PGOOD2Notebook ComputersMAX17101SKIP 29 12 ILIM1Main System Supply (5V and ..
MAX17108ETI+ ,10-Channel High-Voltage Scan Driver and VCOM Amplifier for TFT LCD PanelsELECTRICAL CHARACTERISTICS (continued)(Figure 1 circuit, V = 16V, V = 38V, V = -12V, T = 0°C to +85 ..
MAX17108ETI+T ,10-Channel High-Voltage Scan Driver and VCOM Amplifier for TFT LCD PanelsELECTRICAL CHARACTERISTICS(Figure 1 circuit, V = 16V, V = 38V, V = -12V, T = 0°C to +85°C. Typical ..
MAX1710EEG ,High-Speed / Digitally Adjusted Step-Down Controllers for Notebook CPUsFeaturesThe MAX1710/MAX1711 step-down controllers are' Ultra-High Efficiency intended for core CPU ..
MAX1711 ,High-Speed, Digitally Adjusted Step-Down Controllers for Notebook CPUsApplicationsV+SHDNFBSNotebook ComputersBSTILIMDocking Stations DHGNDSOUTPUT0.925V TO 2VCPU Core DC- ..
MAX4535EPD ,Fault-Protected / High-Voltage / Single 4-to-1/Dual 2-to-1 MultiplexersMAX4534/MAX453519-1609; Rev 0; 1/00Fault-Protected, High-Voltage, Single 4-to-1/Dual 2-to-1 Multipl ..
MAX4535EUD+ ,Fault-Protected, High-Voltage, Single 4-to-1/Dual 2-to-1 MultiplexersFeaturesThe MAX4534 (single 4-to-1) and MAX4535 (dual 2-to-♦ ±40V Fault Protection with Power Off1) ..
MAX4536CPE ,Quad / Low-Voltage / SPST Analog Switches with EnableFeaturesThe MAX4536/MAX4537/MAX4538 are quad, low-voltage,' Pin Compatible with 74HC4316 single-pol ..
MAX4536CSE ,Quad / Low-Voltage / SPST Analog Switches with EnableELECTRICAL CHARACTERISTICS—±5V Dual Supplies(V+ = 4.5V to 5.5V, V- = -4.5V to -5.5V, V = 2.4V, V = ..
MAX4536CSE ,Quad / Low-Voltage / SPST Analog Switches with EnableMAX4536/MAX4537/MAX453819-1148; Rev 0; 11/96Quad, Low-Voltage, SPST Analog Switches with Enable____ ..
MAX4536CSE ,Quad / Low-Voltage / SPST Analog Switches with EnableApplicationsBattery-Operated Equipment PART TEMP. RANGE PIN-PACKAGEMAX4536CPE 0°C to +70°C 16 Plast ..
MAX1710-MAX1711
High-Speed, Digitally Adjusted Step-Down Controllers for Notebook CPUs
General DescriptionThe MAX1710/MAX1711 step-down controllers are
intended for core CPU DC-DC converters in notebook
computers. They feature a triple-threat combination of
ultra-fast transient response, high DC accuracy, and
high efficiency needed for leading-edge CPU core
power supplies. Maxim’s proprietary Quick-PWM™
quick-response, constant-on-time PWM control scheme
handles wide input/output voltage ratios with ease and
provides 100ns “instant-on” response to load transients
while maintaining a relatively constant switching fre-
quency.
High DC precision is ensured by a 2-wire remote-sens-
ing scheme that compensates for voltage drops in both
the ground bus and supply rail. An on-board, digital-to-
analog converter (DAC) sets the output voltage in com-
pliance with Mobile Pentium II®CPU specifications.
The MAX1710 achieves high efficiency at a reduced
cost by eliminating the current-sense resistor found in
traditional current-mode PWMs. Efficiency is further
enhanced by an ability to drive very large synchronous-
rectifier MOSFETs.
Single-stage buck conversion allows these devices to
directly step down high-voltage batteries for the highest
possible efficiency. Alternatively, 2-stage conversion
(stepping down the +5V system supply instead of the
battery) at a higher switching frequency allows the mini-
mum possible physical size.
The MAX1710/MAX1711 are identical except that the
MAX1711 have 5-bit DACs and the MAX1710 has a 4-
bit DAC. Also, the MAX1711 has a fixed overvoltage
protection threshold at VOUT= 2.25V and undervoltage
protection at VOUT= 0.8V whereas the MAX1710 has
variable thresholds that track VOUT. The MAX1711 is
intended for applications where the DAC code may
change dynamically.
ApplicationsNotebook Computers
Docking Stations
CPU Core DC-DC Converters
Single-Stage (BATT to VCORE)Converters
Two-Stage (+5V to VCORE) Converters
FeaturesUltra-High Efficiency No Current-Sense Resistor (Lossless ILIMIT)Quick-PWM with 100ns Load-Step Response±1% VOUTAccuracy over Line and Load4-Bit On-Board DAC (MAX1710)5-Bit On-Board DAC(MAX1711/MAX1712)0.925V to 2V Output Adjust Range
(MAX1711/MAX1712)2V to 28V Battery Input Range 200/300/400/550kHz Switching FrequencyRemote GND and VOUTSensingOver/Undervoltage Protection1.7ms Digital Soft-StartDrive Large Synchronous-Rectifier FETs2V ±1% Reference Output Power-Good IndicatorSmall 24-Pin QSOP Package
MAX1710/MAX1711/MAX1712
High-Speed, Digitally Adjusted
Step-Down Controllers for Notebook CPUs19-4781; Rev 1; 7/00
Pin Configurations appear at end of data sheet.Quick-PWM is a trademark of Maxim Integrated Products.
Mobile Pentium II is a registered trademark of Intel Corp.
-40°C to +85°C
PART
MAX1710EEG
TEMP. RANGEPIN-PACKAGE24 QSOP
Ordering Information
MAX1711EEG-40°C to +85°C24 QSOP
SKIP
GND
BST
+5V INPUT
ILIM
GNDS
FBS
D4**
*MAX1710 ONLY
REF
PGND
MAX1710
MAX1711
MAX1712
VCCOVP*VDD
SHDN
OUTPUT
0.925V TO 2V(MAX1711/MAX1712)
D/AINPUTS
BATTERY 4.5V TO 28V
Minimal Operating Circuit
EVALUATION KIT
AVAILABLE
MAX1710/MAX1711/MAX1712
High-Speed, Digitally Adjusted
Step-Down Controllers for Notebook CPUs
ABSOLUTE MAXIMUM RATINGSStresses 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 +30V
VCC, VDDto GND.....................................................-0.3V to +6V
PGND to GND.....................................................................±0.3V
SHDN, PGOOD to GND...........................................-0.3V to +6V
OVP,ILIM, FB, FBS, CC, REF, D0–D4,
GNDS, TON to GND..............................-0.3V to (VCC+ 0.3V)
SKIPto GND (Note 1).................................-0.3V to (VCC+ 0.3V)
DL to PGND................................................-0.3V to (VDD+ 0.3V)
BST to GND............................................................-0.3V to +36V
DH to LX.....................................................-0.3V to (BST + 0.3V)
LX to BST..................................................................-6V to +0.3V
REF Short Circuit to GND...........................................Continuous
Continuous Power Dissipation (TA= +70°C)
24-Pin QSOP (derate 9.5mW/°C above +70°C)..........762mW
Operating Temperature Range...........................-40°C to +85°C
Junction Temperature......................................................+150°C
Storage Temperature Range.............................-65°C to +165°C
Lead Temperature (soldering, 10s).................................+300°C
VBATT= 4.5V to 28V, includes
load regulation error
SHDN= 0, measured at V+ = 28V, VCC= VDD= 0 or 5V
SHDN= 0
VCC,VDD
SHDN= 0
Battery voltage, V+
Measured at V+
Measured at VDD, FB forced above the regulation point
Measured at VCC, FB forced above the regulation point
Rising edge of SHDNto full ILIM
(Note 2)
VBATT= 24V,
FB = 2V
(Note 2)
FB (MAX1710 only) or FBS
FB - FBS or GNDS - GND = 0 to 25mV
VCC= 4.5V to 5.5V, VBATT= 4.5V to 28V
CONDITIONS<15Shutdown Battery Supply
Current <15Shutdown Supply Current (VDD)<15Shutdown Supply Current (VCC)2540Quiescent Battery Supply Current <15Quiescent Supply Current (VDD)600950Quiescent Supply Current (VCC)400500Minimum Off-Time
DC Output Voltage Accuracy
TON = REF (400kHz)
4.55.5V228Input Voltage Range
TON = GND (550kHz)
On-Time 1.7Soft-Start Ramp Time-11GNDS Input Bias Current-0.20.2FB Input Bias Current
TON = open (300kHz)3Remote-Sense Voltage Error5Line Regulation Error
UNITMINTYPMAXPARAMETERREF in regulation
IREF= 0 to 50µA
VCC= 4.5V to 5.5V, no external REF load10REF Sink Current0.01Reference Load Regulation1.9822.02Reference Voltage
TON = VCC(200kHz)
Note 1:SKIPmay be forced below -0.3V, temporarily exceeding the absolute maximum rating, for the purpose of debugging proto-
type breadboards using the no-fault test mode. Limit the current drawn to -5mA maximum.
ELECTRICAL CHARACTERISTICS(Circuit of Figure 1, VBATT= 15V, VCC= VDD= 5V, SKIP= GND, TA= 0°C to +85°C, unless otherwise noted.) 130180240FB Input Resistance
(MAX1711/MAX1712)
DAC codes from 1.3V to 2V
ILOAD= 0 to 7AmV9Load Regulation Error
DAC codes from 0.925V
to 1.275V
With respect to unloaded output voltage
MAX1710/MAX1711/MAX1712
High-Speed, Digitally Adjusted
Step-Down Controllers for Notebook CPUs
ELECTRICAL CHARACTERISTICS (continued)(Circuit of Figure 1, VBATT= 15V, VCC= VDD= 5V, SKIP= GND, TA= 0°C to +85°C, unless otherwise noted.)
CONDITIONSUNITMINTYPMAXPARAMETERLX to PGND
LX to PGND, ILIM tied to VCC
From SHDNsignal going high405060Current-Limit Threshold
(Positive Direction, Adjustable)90100110Current-Limit Threshold
(Positive Direction, Fixed)1030Output Undervoltage Protection
Time 657075Output Undervoltage Protection
Threshold
LX to PGND, TA= +25°CmV-150-120-80Current-Limit Threshold
(Negative Direction)
RLIM= 100kΩ
RLIM= 400kΩ170200230
Rising edge, hysteresis = 20mV,
PWM disabled below this levelV4.14.4VCCUndervoltage Lockout
Threshold
BST-LXforced to 5VΩ5DHGate-Driver On-Resistance
DL, high stateΩ5DLGate-Driver On-Resistance
(Pullup)
DL, low stateΩ0.51.7DLGate-Driver On-Resistance
(Pulldown)
DH forced to 2.5V, BST-LX forced to 5VA1DHGate-Driver Source/Sink
Current
DL forced to 2.5VA3DLGate-Driver Sink Current
DL forced to 2.5VA1DLGate-Driver Source Currentforced 2% above trip thresholdµs1.5Overvoltage Fault Propagation
Delay10.512.514.5Overvoltage Trip Threshold
FB forced 2% below PGOOD trip threshold, falling edgeµs1.5PGOODPropagation Delay
LX to PGNDmV3Current-Limit Threshold
(Zero Crossing)
ISINK= 1mAV0.4PGOOD Output Low Voltage
High state, forced to 5.5VµA1PGOOD Leakage Current
Hysteresis = 10°C°C150Thermal Shutdown Threshold2.212.252.29
With respect to unloaded output voltage (MAX1710)
With respect to unloaded output voltage (MAX1710)
(MAX1711/MAX1712)V
DL risingns35Dead TimeDH rising26SKIPInput Current Logic
ThresholdTo enable no-fault mode, TA= +25°C-1.5-0.1PGOODTrip ThresholdMeasured at FB with respect to unloaded output voltage,
falling edge, hysteresis = 1%-8-5-3Logic Input High VoltageD0–D4, SHDN, SKIP, OVP2.4Logic Input Low VoltageD0–D4, SHDN, SKIP, OVP0.8Logic Input CurrentSHDN, SKIP, OVP-11
(MAX1711/MAX1712)
MAX1710/MAX1711/MAX1712
High-Speed, Digitally Adjusted
Step-Down Controllers for Notebook CPUs1015
VBATT= 4.5V to 28V, for all
D/A codes, includes load
regulation error
VCC,VDD
Battery voltage, V+
Measured at VCC, FB forced above the regulation point
Overvoltage Trip Threshold
(Note 2)
VBATT= 24V,
FB = 2V
(Note 2)
With respect to unloaded output voltage (MAX1710)%
CONDITIONS75Output Undervoltage
Protection Threshold 950Quiescent Supply Current (VCC)500Minimum Off-Time
DC Output Voltage Accuracy
TON = REF (400kHz)
4.55.5V228Input Voltage Range
TON = GND (550kHz)
On-Time TON = open (300kHz)
UNITMINTYPMAXPARAMETERVCC= 4.5V to 5.5V, no external REF loadV1.982.02Reference Voltage
TON = VCC(200kHz)
LX to PGND, ILIM tied to VCCmV85115Current-Limit Threshold
(Positive Direction, Fixed)
LX to PGNDmV3565Current-Limit Threshold
(Positive Direction, Adjustable)
RLIM= 100kΩ
RLIM= 400kΩ160240
Rising edge, hysteresis = 20mV, PWM disabled below
this level4.14.4VCCUndervoltage Lockout
ThresholdV
D0–D4, SHDN, SKIP, OVPV2.4Logic Input High Voltage
D0–D4, SHDN, SKIP, OVPV0.8Logic Input Low Voltage
SHDN, SKIP, OVPµA-11Logic Input Current
D0–D4, each forced to GNDµA310Logic Input Pullup Current
ELECTRICAL CHARACTERISTICS (Circuit of Figure 1, VBATT= 15V, VCC = VDD= 5V, SKIP= GND, TA
= -40°C to +85°C,unless otherwise noted.) (Note 3)2.202.30
0.750.85V
ELECTRICAL CHARACTERISTICS (continued)(Circuit of Figure 1, VBATT= 15V, VCC= VDD= 5V, SKIP= GND, TA= 0°C to +85°C, unless otherwise noted.)
CONDITIONSTON logic input high levelVVCC- 0.4TON VCCLevel
TON logic input upper-midrange levelV3.153.85TON Float Voltage
TON logic input lower-midrange levelV1.652.35TON Reference Level
TON logic input low levelV0.5TON GND Level
TON only, forced to GND or VCCµA-33TON Logic Input Current
UNITMINTYPMAXPARAMETERWith respect to unloaded output voltage (MAX1710)
(MAX1711/MAX1712)
(MAX1711/MAX1712)-1.71.7
DACcodes from 1.32V to 2V
DACcodes from 0.925V to
1.275V
MAX1710/MAX1711/MAX1712
High-Speed, Digitally Adjusted
Step-Down Controllers for Notebook CPUsEFFICIENCY vs. LOAD CURRENT
(VO = 2.0V, f = 300kHz)
MAX1710-01
LOAD CURRENT (A)
EFFICIENCY (%)
VIN = 4.5V
VIN = 7V
VIN = 15V
VIN = 24V
EFFICIENCY vs. LOAD CURRENT
(VO = 1.6V, f = 300kHz)
MAX1710-02
LOAD CURRENT (A)
EFFICIENCY (%)
VIN = 4.5V
VIN = 24V
VIN = 7V
VIN = 15V
EFFICIENCY vs. LOAD CURRENT
(VO = 1.3V, f = 300kHz)
MAX1710-03
LOAD CURRENT (A)
EFFICIENCY (%)
VIN = 4.5V
VIN = 24V
VIN = 15V
VIN = 7V
EFFICIENCY vs. LOAD CURRENT
(VO = 1.6V, f = 550kHz)
MAX1710-04
LOAD CURRENT (A)
EFFICIENCY (%)
VIN = 4.5V
VIN = 15V
VIN = 7V
VIN = 24V
FREQUENCY vs. LOAD CURRENT
(VO = 1.6V)
MAX1710-05
LOAD CURRENT (A)
FREQUENCY (kHz)
VIN = 15V, PWM MODE
VIN = 4.5V, SKIP MODE
VIN = 15V, SKIP MODE
TON = OPEN
FREQUENCY vs. INPUT VOLTAGE
(IO = 7A)
MAX1710-06
FREQUENCY (kHz)
VO = 2.0V
VO = 1.6V
TON = OPEN
Note 2:On-Time and Off-Time specifications are measured from 50% point to 50% point at the DH pin with LX forced to 0V, BST
forced to 5V, and a 250pF capacitor connected from DH to LX. Actual in-circuit times may differ due to MOSFET switching
speeds.
Note 3:Specifications from -40°C to 0°C are guaranteed but not production tested.
__________________________________________Typical Operating Characteristics(7A CPU supply circuit of Figure 1, TA= +25°C, unless otherwise noted.)
CONDITIONSMeasured at FB with respect to unloaded output voltage,
falling edge, hysteresis = 1%%-8.5-2.5PGOOD Trip Threshold
ISINK= 1mAV0.4PGOOD Output Low Voltage
High state, forced to 5.5VµA1PGOOD Leakage Current
UNITMINTYPMAXPARAMETER
ELECTRICAL CHARACTERISTICS (continued)(Circuit of Figure 1, VBATT= 15V, VCC = VDD= 5V, SKIP= GND, TA
= -40°C to +85°C,unless otherwise noted.) (Note 3)
MAX1710/MAX1711/MAX1712
High-Speed, Digitally Adjusted
Step-Down Controllers for Notebook CPUs
_____________________________Typical Operating Characteristics (continued)(7A CPU supply circuit of Figure 1, TA= +25°C, unless otherwise noted.)
CONTINUOUS TO DISCONTINUOUS
INDUCTOR CURRENT POINT
vs. INPUT VOLTAGE
MAX1710-10
INPUT VOLTAGE (V)
LOAD CURRENT (A)
VO = 2.0V
VO = 1.6V
VO = 1.3V
INDUCTOR CURRENT PEAKS AND
VALLEYS vs. INPUT VOLTAGE
(AT CURRENT-LIMIT POINT)
MAX1710-11
INPUT VOLTAGE (V)
INDUCTOR CURRENT (A)
IPEAK
IVALLEY
NO-LOAD SUPPLY CURRENTS
vs. INPUT VOLTAGE
(SKIP MODE, f = 300kHz)
MAX1710-12
INPUT VOLTAGE (V)
SUPPLY CURRENT (mA)
ICC
IBATT
IDD
NO-LOAD SUPPLY CURRENTS
vs. INPUT VOLTAGE
(SKIP MODE, f = 550kHz)
MAX1710-13
INPUT VOLTAGE (V)
SUPPLY CURRENT (mA)
ICC
IBATT
IDD
NO-LOAD SUPPLY CURRENTS
vs. INPUT VOLTAGE
(PWM MODE, f = 300kHz)
MAX1710-14
INPUT VOLTAGE (V)
SUPPLY CURRENT (mA)
IDD
IBAT
ICC
NO-LOAD SUPPLY CURRENTS
vs. INPUT VOLTAGE
(PWM MODE, f = 550kHz)
MAX1710-15
INPUT VOLTAGE (V)
SUPPLY CURRENT (mA)
IDD
IBAT
ICC
FREQUENCY vs. TEMPERATURE
(VIN = 15V, VO = 2.0V)
MAX1710-07
TEMPERATURE (°C)
FREQUENCY (kHz)
IO = 7A
IO = 4A
IO = 1ATON = OPEN
ON-TIME vs. TEMPERATURE
MAX1710-08
TEMPERATURE (°C)
ON-TIME (ns)
IO = 1A
IO = 4A OR 7A
CURRENT-LIMIT TRIP POINT
vs. TEMPERATURE
MAX1710-09
TEMPERATURE (°C)
CURRENT TRIP POINT (A)
ILIM = 400kΩ
ILIM = VCC
ILIM = 100kΩ
10μs/div
LOAD-TRANSIENT RESPONSE
(WITH INTEGRATOR)VIN = 15V, VO = 1.6V, IO = 0A TO 7A
A = VOUT, AC-COUPLED, 50mV/div
B = INDUCTOR CURRENT, 5A/div
MAX1710-16
10μs/div
LOAD-TRANSIENT RESPONSE
(WITH INTEGRATOR)VIN = 15V, VO = 1.6V, IO = 30mA TO 7A
A = VOUT, AC-COUPLED, 50mV/div
B = INDUCTOR CURRENT, 5A/div
MAX1710-17
MAX1710/MAX1711/MAX1712
High-Speed, Digitally Adjusted
Step-Down Controllers for Notebook CPUs
_____________________________Typical Operating Characteristics (continued)(7A CPU supply circuit of Figure 1, TA= +25°C, unless otherwise noted.)
20μs/div
LOAD-TRANSIENT RESPONSE
(WITH INTEGRATOR)VIN = 4.5V, VO = 2V, IO = 30mA TO 7A
A = VOUT, AC-COUPLED, 50mV/div
B = INDUCTOR CURRENT, 5A/div
C = DL, 10V/div
MAX1710-19
20μs/div
LOAD-TRANSIENT RESPONSE
(WITH INTEGRATOR)VIN = 4.5V, VO = 1.3V, IO = 30mA TO 7A
A = VOUT, AC-COUPLED, 50mV/div
B = INDUCTOR CURRENT, 5A/div
C = DL, 10V/div
MAX1710-20
500μs/div
STARTUP WAVEFORMA = SHDN
B = VOUT, 0.5V/div
C = INDUCTOR CURRENT, 5A/div
MAX1710-21
10μs/div
LOAD-TRANSIENT RESPONSE
(WITHOUT INTEGRATOR)VIN = 15V, VO = 1.6V, IO = 30mA TO 7A
A = VOUT, AC-COUPLED, 50mV/div
B = INDUCTOR CURRENT, 5A/div
MAX1710-18
MAX1710/MAX1711/MAX1712
High-Speed, Digitally Adjusted
Step-Down Controllers for Notebook CPUs50μs/div
OUTPUT OVERLOAD WAVEFORMVOUT = 1.6V
A = VIN, AC-COUPLED, 2V/div
B = VOUT, 0.5V/div
C = INDUCTOR CURRENT, 5A/div
MAX1710-22
5μs/div
LOAD-TRANSIENT RESPONSEL = 0.7μH, VOUT = 1.6V, VIN = 15V, COUT = 47μF (x4), f = 550kHz
A = VOUT, AC-COUPLED, 100mV/div
B = INDUCTOR CURRENT, 5A/div
C = DL, 5V/div
MAX1710-23
CERAMIC COUT
5μs/div
SHUTDOWN WAVEFORMVIN = 15V, V0 = 1.6V, I0 = 7A
A = VOUT, 0.5V/div
B = INDUCTOR CURRENT, 5A/div
C = SHDN, 2V/div
D = DL, 5V/div
MAX1710-24
_____________________________Typical Operating Characteristics (continued)(7A CPU supply circuit of Figure 1, TA= +25°C, unless otherwise noted.)
Pin Description
NAMEFUNCTIONCCIntegrator Capacitor Connection. Connect a 100pF to 1000pF (470pF typical) capacitor to GND to set the
integration time constant.
PINFBS
Feedback Remote-Sense Input, normally connected to VOUTdirectly at the load. FBS internally connects to
the integrator that fine tunes the DC output voltage. Tie FBS to VCCto disable all three integrator amplifiers.
Tie FBS to FB (or disable the integrators) when externally adjusting the output voltage with a resistor-divider. FBFast Feedback Input, normally connected to VOUT. FB is connected to the bulk output filter capacitors local-
ly at the power supply. An external resistor-divider can optionally set the output voltage.TONOn-Time Selection Control Input. This is a four-level input that sets the K factor to determine DH on-time.
GND = 550kHz, REF = 400kHz, open = 300kHz, VCC= 200kHz.VCCAnalog Supply Voltage Input for PWM Core, 4.5V to 5.5V. Bypass VCCto GND with a 0.1µF minimum
capacitor.ILIM
Current-Limit Threshold Adjustment. Connects to an external resistor to GND. The LX-PGND current-limit
threshold defaults to +100mV if ILIM is tied to VCC. The current-limit threshold is 1/10 of the voltage forced at
ILIM. In adjustable mode, the threshold is VTH = RLIM✕5µA/10.V+Battery Voltage Sense Connection. V+ is used only for PWM one-shot timing. DH on-time is inversely propor-
tional to V+ input voltage over a range of 2V to 28V.REF
2.0V Reference Output. Bypass REF to GND with a 0.22µF minimum capacitor. REF can source 50µA for
external loads. Loading REF degrades FB accuracy according to the REF load-regulation error
(see Electrical Characteristics).SHDNShutdown Control Input, active low. SHDNcannot withstand the battery voltage. In shutdown mode, DL is
forced to VDDin order to enforce overvoltage protection, even when powered down (unless OVPis high).
MAX1710/MAX1711/MAX1712
High-Speed, Digitally Adjusted
Step-Down Controllers for Notebook CPUs
Standard Application CircuitThe standard application circuit (Figure 1) generates a
low-voltage, high-power rail for supplying up to 7A to the
core CPU VCCin a notebook computer. This DC-DC
converter steps down a battery or AC adapter voltage to
sub-2V levels with high efficiency and accuracy, and
represents a good compromise between size, efficiency,
and cost.
See the MAX1710 EV kit manual for a list of components
and suppliers.
Detailed DescriptionThe MAX1710/MAX1711/MAX1712 buck controllers are
targeted for low-voltage, high-current CPU power sup-
plies for notebook computers. CPU cores typically exhib-
it 0A to 10A or greater load steps when the clock is
throttled. The proprietary Quick-PWM pulse-width modu-
lator in the MAX1710/MAX1711/MAX1712 is specifically
designed for handling these fast load steps while main-
taining a relatively constant operating frequency and
inductor operating point over a wide range of input volt-
ages. The Quick-PWM architecture circumvents the poor
load-transient timing problems of fixed-frequency cur-
Pin Description (continued)
NAMEFUNCTION(MAX1711/
MAX1712)DAC Code Input, MSB. 5µA internal pullup to VCC(Tables 1, 2, and 3).
PINDLLow-Side Gate-Driver Output, swings 0 to VDDPGOODOpen-Drain Power-Good Output GNDSGround Remote-Sense Input, normally connected to ground directly at the load. GNDS internally con-
nects to the integrator that fine tunes the ground offset voltage. GNDAnalog GroundPGNDPower Ground. Also used as the inverting input for the current-limit comparator.VDDSupply Voltage Input for the DL Gate Driver, 4.5V to 5.5V D3DAC Code Input. 5µA internal pullup to VCC.
(MAX1710)OVPOvervoltage-Protection Disable Control Input (Table 4). GND = normal operation and overvoltage
protection active, VCC = overvoltage protection disabled.BST
Boost Flying-Capacitor Connection. An optional resistor in series with BST allows the DH pullup
current to be adjusted (Figure 5). This technique of slowing the LX rise time can be used to prevent
accidental turn-on of the low-side MOSFET due to excessive gate-drain capacitance. SKIP
Low-Noise-Mode Selection Control Input. Low-noise forced-PWM mode causes inductor current
recirculation at light loads and suppresses pulse-skipping operation. Normal operation prevents
current recirculation. SKIPcan also be used to disable both overvoltage and undervoltage protection
circuits and clear the fault latch (Figure 6). GND = normal operation, VCC= low-noise mode.
Do not
leave SKIPfloating.D0DAC Code Input LSB. 5µA internal pullup.D1DAC Code Input. 5µA internal pullup.D2DAC Code Input. 5µA internal pullup.DHHigh-Side Gate-Driver Output. Swings LX to BST.LX
Inductor Connection. LX serves as the lower supply rail for the DH high-side gate driver. Also used
for the noninverting input to the current-limit comparator, as well as the skip-mode zero-crossing com-
parator.
MAX1710/MAX1711/MAX1712rent-mode PWMs while also avoiding the problems
caused by widely varying switching frequencies in con-
ventional constant-on-time and constant-off-time PWM
schemes.
+5V Bias Supply (VCCand VDD)The MAX1710/MAX1711/MAX1712 require an external
+5V bias supply in addition to the battery. Typically, this
+5V bias supply is the notebook’s 95% efficient 5V sys-
tem supply. Keeping the bias supply external to the IC
improves efficiency and eliminates the cost associated
with the +5V linear regulator that would otherwise be
needed to supply the PWM circuit and gate drivers. If
stand-alone capability is needed, the +5V supply can be
generated with an external linear regulator such as the
MAX1615.
The battery and +5V bias inputs can be tied together if
the input source is a fixed 4.5V to 5.5V supply. If the +5V
bias supply is powered up prior to the battery supply, the
enable signal (SHDN) must be delayed until the battery
voltage is present in order to ensure startup. The +5V
bias supply must provide VCCand gate-drive power, so
the maximum current drawn is:
High-Speed, Digitally Adjusted
Step-Down Controllers for Notebook CPUsVCC
VBATT
4.5V TO 28V
+5V
BIAS SUPPLY
3 x 470μF
KEMET T510
PANASONIC
ETQP6F2R0HFA
POWER-GOOD
INDICATOR
*MAX1710 ONLY
**MAX1711/MAX1712 ONLY
2μH
VOUT
1.25V TO 2V AT 7A (MAX1710)
0.925V TO 2V AT 7A (MAX1711)
1.1V TO 1.85V AT 7A (MAX1712)
SHDN22115
CMPSH-3
1μF
0.1μF
1μF
470pF
TO VCC
100k
(OPTIONAL OVP
REVERSE-POLARITY
CLAMP)Q2
1μFR1
20Ω
C1 3 x 10μF/30V
SKIPDAC
INPUTS
ON/OFF
CONTROL
LOW-NOISE
CONTROL
BST
PGND
FBS
GNDS
Q1 = IRF7807
Q2 = IRF7805
D1, D3 = MBRS130T3 (OPTIONAL)
C1 = SANYO OS-CON (30SC10M)
PGOOD
VDD
MAX1710
MAX1711
MAX171216
+5VD4**
TON
REF
GND
(OPTIONAL)
ILIMOVP*
Figure 1. Standard Application Circuit
IBIAS= ICC+ f ✕(QG1+ QG2) = 15mA to 30mA (typ)
where ICCis 600µA (typ), f is the switching frequency,
and QG1and QG2are the MOSFET data sheet total
gate-charge specification limits at VGS= 5V.
Free-Running, Constant-On-Time PWM
Controller with Input Feed-ForwardThe Quick-PWM control architecture is an almost fixed-
frequency, constant-on-time current-mode type with volt-
age feed-forward (Figure 2). This architecture relies on
the filter capacitor’s ESR to act as the current-sense
resistor, so the output ripple voltage provides the PWM
ramp signal. The control algorithm is simple: the high-
side switch on-time is determined solely by a one-shot
whose period is inversely proportional to input voltage
and directly proportional to output voltage. Another one-
shot sets a minimum off-time (400ns typ). The on-time
one-shot is triggered if the error comparator is low, the
MAX1710/MAX1711/MAX1712
High-Speed, Digitally Adjusted
Step-Down Controllers for Notebook CPUsREF
-5%
FROM
D/A
REF
REFD1D2D3
10k
ERROR
AMP
TOFF
TON
REF
+12%
REF
-30%
R-2R
D/A CONVERTER
CHIP SUPPLYgmgm
GNDS
SHDN
FBS
PGOOD
OVP/UVLO
LATCH
ON-TIME
COMPUTE
TON
1-SHOT
1-SHOT
TRIG
VBATT 2V TO 28V
TRIG
REF
GND
REF
PGND
+5V
OUTPUT
VCC
VCC
VDD
ZERO CROSSING
CURRENT
LIMIT
BST
ILIM
RLIM
+5V
5μA
+5VTIMER
SKIP
OVP
TON
70k
MAX1710
Figure 2. MAX1710 Functional Diagram
MAX1710/MAX1711/MAX1712
High-Speed, Digitally Adjusted
Step-Down Controllers for Notebook CPUslow-side switch current is below the current-limit thresh-
old, and the minimum off-time one-shot has timed out.
On-Time One-Shot (TON)The heart of the PWM core is the one-shot that sets the
high-side switch on-time. This fast, low-jitter, adjustable
one-shot includes circuitry that varies the on-time in
response to battery and output voltage. The high-side
switch on-time is inversely proportional to the battery
voltage as measured by the V+ input, and directly pro-
portional to the output voltage as set by the DAC code.
This algorithm results in a nearly constant switching fre-
quency despite the lack of a fixed-frequency clock gen-
erator. The benefits of a constant switching frequency
are twofold: first, the frequency can be selected to avoid
noise-sensitive regions such as the 455kHz IF band;
second, the inductor ripple-current operating point
remains relatively constant, resulting in easy design
methodology and predictable output voltage ripple:
On-Time = K (VOUT+ 0.075V) / VIN
where K is set by the TON pin-strap connection and
0.075V is an approximation to accommodate for the
expected drop across the low-side MOSFET switch.
One-shot timing error increases for the shorter on-time
settings due to fixed propagation delays and is approxi-
mately ±12.5% at 550kHz and 400kHz, and ±10% at the
two slower settings. This translates to reduced switch-
ing-frequency accuracy at higher frequencies (Table 5).
Switching frequency increases as a function of load cur-
rent due to the increasing drop across the low-side
Table 1. MAX1710 FBOutput Voltage
DAC CodesD2D1D0OUTPUT
VOLTAGE (V)0001.600002.000011.950101.900111.851001.801011.751101.701111.650011.550101.500111.451001.401011.351101.301111.25
Table 2. MAX1711 FBOutput Voltage
DAC CodesD3D2D1OUTPUT
VOLTAGE (V)1001.600002.000001.950011.900011.850101.800101.750111.700111.651001.551011.501011.451101.401101.351111.30111Shutdown3* 1001.0750001.2750001.2500011.2250011.2000101.1750101.1500111.1250111.1001001.0501011.0251011.0001100.9751100.9501110.925111Shutdown3*
*See Table 4.
MAX1710/MAX1711/MAX1712
High-Speed, Digitally Adjusted
Step-Down Controllers for Notebook CPUsMOSFET, which causes a faster inductor-current dis-
charge ramp. The on-times guaranteed in the Electrical
Characteristics are influenced by switching delays in the
external high-side power MOSFET. The exact switching
frequency will depend on gate charge, internal gate
resistance, source inductance, and DH output drive
characteristics.
Two external factors that can influence switching-fre-
quency accuracy are resistive drops in the two conduc-
tion loops (including inductor and PC board resistance)
and the dead-time effect. These effects are the largest
contributors to the change of frequency with changing
load current. The dead-time effect is a notable disconti-
nuity in the switching frequency as the load current is
varied (see Typical Operating Characteristics). It occurs
whenever the inductor current reverses, most commonly
at light loads with SKIPhigh. With reversed inductor cur-
rent, the inductor’s EMF causes LX to go high earlier
than normal, extending the on-time by a period equal to
the low-to-high dead time. For loads above the critical
conduction point, the actual switching frequency is:
where VDROP1is the sum of the parasitic voltage drops
in the inductor discharge path, including synchronous
rectifier, inductor, and PC board resistances; VDROP2
is the sum of the resistances in the charging path,
and tONis the on-time calculated by the MAX1710/
MAX1711/MAX1712.
Integrator Amplifiers (CC)There are three integrator amplifiers that provide a fine
adjustment to the output regulation point. One amplifier
monitors the difference between GNDS and GND, while
another monitors the difference between FBS and FB.
The third amplifier integrates the difference between
REF and the DAC output. These three transconductance
amplifiers’ outputs are directly summed inside the chip,
so the integration time constant can be set easily with a
capacitor. The gmof each amplifier is 160µmho (typ).
The integrator block has an ability to move and correct
the output voltage by about -2%, +4%. For each amplifi-
er, the differential input voltage range is about ±50mV
total, including DC offset and AC ripple. The voltage
gain of each integrator is about 80V/V.
The FBS amplifier corrects for DC voltage drops in PC
board traces and connectors in the output bus path
between the DC-DC converter and the load. The GNDS
amplifier performs a similar DC correction task for the
output ground bus. The third amplifier provides an aver-
aging function that forces VOUTto be regulated at the
average value of the output ripple waveform. If the inte-
grator amplifiers are disabled, VOUTis regulated at the
valleys of the output ripple waveform. This creates a
slight load-regulation characteristic in which the outputVVV
OUTDROPINDROP=+ ()
Table 3. MAX1712 FBOutput Voltage
DAC Codes (VRM 9.0)*See Table 4.
Shutdown3* 1111
1.475 1110
OUTPUT
VOLTAGE (V)D1D2D3D4
MAX1710/MAX1711
High-Speed, Digitally Adjusted
Step-Down Controllers for Notebook CPUsvoltage rises approximately 1% (up to 1/2 the peak
amplitude of the ripple waveform as a limit) when under
light loads.
Integrators have both beneficial and detrimental char-
acteristics. While they do correct for drops due to DC
bus resistance and tighten the DC output voltage toler-
ance limits by averaging the peak-to-peak output
ripple, they can interfere with achieving the fastest pos-
sible load-transient response. The fastest transient
response is achieved when all three integrators are dis-
abled. This works very well when the MAX1710/
MAX1711/MAX1712 circuit can be placed very close to
the CPU.
There is often a connector, or at least many milliohms of
PC board trace resistance, between the DC-DC convert-
er and the CPU. In these cases, the best strategy is to
place most of the bulk bypass capacitors close to the
CPU, with just one capacitor on the other side of the con-
nector near the MAX1710/MAX1711/MAX1712 to control
ripple if the CPU card is unplugged. In this situation, the
remote-sense lines and integrators provide a real benefit.
When FBS is connected to VCCso that all three integra-
tors are disabled, CC can be left unconnected, which
eliminates a component.
Automatic Pulse-Skipping SwitchoverAt light loads, an inherent automatic switchover to PFM
takes place. This switchover is effected by a comparator
that truncates the low-side switch on-time at the inductor
current’s zero crossing. This mechanism causes the
threshold between pulse-skipping PFM and nonskipping
PWM operation to coincide with the boundary between
continuous and discontinuous inductor-current operation
(also known as the “critical conduction” point;
see Continuous to Discontinuous Inductor Current Point
vs. Input Voltage graph in the Typical Operating
Characteristics). For a battery range of 7V to 24V, this
threshold is relatively constant, with only a minor depen-
dence on battery voltage.
where K is the On-Time Scale factor (Table 6). The load-
current level at which PFM/PWM crossover occurs,
ILOAD(SKIP), is equal to 1/2 the peak-to-peak ripple cur-
rent, which is a function of the inductor value (Figure 3).
For example, in the standard application circuit with tON
= 300ns at 24V, VOUT= 2V, and L = 2µH, switchover to
pulse-skipping operation occurs at ILOAD= 1.65A or
about 1/4 full load. The crossover point occurs at an
even lower value if a swinging (soft-saturation) inductor
is used.
The switching waveforms may appear noisy and asyn-
chronous when light loading causes pulse-skipping
operation, but this is a normal operating condition that
results in high light-load efficiency. Trade-offs in PFM
noise vs. light-load efficiency can be made by varying
the inductor value. Generally, low inductor values pro-
duce a broader efficiency vs. load curve, while higher
values result in higher full-load efficiency (assuming that
the coil resistance remains fixed) and less output voltage
ripple. Penalties for using higher inductor values include
larger physical size and degraded load-transient
response (especially at low input voltage levels).
Forced-PWM Mode (SSKKIIPP = High)
The low-noise, forced-PWM mode (SKIPdriven high) dis-
ables the zero-crossing comparator, which controls the
low-side switch on-time. This causes the low-side gate-
drive waveform to become the complement of the high-
side gate-drive waveform. This in turn causes the
inductor current to reverse at light loads, as the PWM
loop strives to maintain a duty ratio of VOUT/VIN. The
benefit of forced-PWM mode is to keep the switching fre-
quency fairly constant, but it comes at a cost: the no-
load battery current can be as high as 40mA or more.
Forced-PWM mode is most useful for reducing audio-fre-
quency noise, improving load-transient response, pro-
viding sink-current capability for dynamic output voltage
adjustment, and improving the cross-regulation of multi-
ple-output applications that use a flyback transformer or
coupled inductor.
Current-Limit Circuit (ILIM)The current-limit circuit employs a unique “valley” cur-
rent-sensing algorithm that uses the on-state resistance
of the low-side MOSFET as a current-sensing element. If
the current-sense signal is above the current-limit
threshold, the PWM is not allowed to initiate a new cycle
(Figure 4). The actual peak current is greater than theKLOADSKIP () ≈2
Figure 3. Pulse-Skipping/Discontinuous Crossover Point
INDUCTOR CURRENT
ILOAD = IPEAK/2
ON-TIME0TIME
-IPEAKL
VBATT - VOUTΔi=
