Maxim MAX1711EEG, MAX1710EEG Datasheet

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General Description

The 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 frequency.

High DC precision is ensured by a 2-wire remote-sensing scheme that compensates for voltage drops in both ground bus and the supply rail. An on-board, digital-toanalog converter (DAC) sets the output voltage in compliance 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 synchronousrectifier 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 minimum possible physical size.

The MAX1710 and MAX1711 are identical except that the MAX1711 has a 5-bit DAC rather than a 4-bit DAC. Also, the MAX1711 has a fixed overvoltage protection threshold at V

OUT

= 2.25V and undervoltage protection

at V

OUT

= 0.8V, whereas the MAX1710 has variable

thresholds that track V

OUT

. The MAX1711 is intended for applications where the DAC code may change dynamically.

Applications

Notebook Computers Docking Stations CPU Core DC-DC Converters Single-Stage (BATT to V

CORE)

Converters

Two-Stage (+5V to V

CORE

) Converters

Features

♦ Ultra-High Efficiency ♦ No Current-Sense Resistor (Lossless I

LIMIT

)

♦ QUICK-PWM with 100ns Load-Step Response ♦ ±1% V

OUT

Accuracy over Line and Load

♦ 4-Bit On-Board DAC (MAX1710) ♦ 5-Bit On-Board DAC (MAX1711) ♦ 0.925V to 2V Output Adjust Range (MAX1711) ♦ 2V to 28V Battery Input Range ♦ 200/300/400/550kHz Switching Frequency ♦ Remote GND and V

OUT

Sensing

♦ Over/Undervoltage Protection ♦ 1.7ms Digital Soft-Start ♦ Drives Large Synchronous-Rectifier FETs ♦ 2V ±1% Reference Output ♦ Power-Good Indicator ♦ Small 24-Pin QSOP Package

MAX1710/MAX1711

High-Speed, Digitally Adjusted

Step-Down Controllers for Notebook CPUs

________________________________________________________________

Maxim Integrated Products

19-4781; Rev 0; 11/98

Pin Configuration appears 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. RANGE PIN-PACKAGE

24 QSOP

Ordering Information

MAX1711EEG -40°C to +85°C 24 QSOP

EVALUATION KIT MANUAL

FOLLOWS DATA SHEET

SKIP

GND

LX DL

BST

+5V INPUT

ILIM GNDS

FBS

D0 D1 D2 D3 D4**

*MAX1710 ONLY **MAX1711 ONLY

REF CC

PGND

MAX1710 MAX1711

V+

OVP* V

SHDN

OUTPUT

0.925V TO 2V (MAX1711)

D/A

INPUTS

BATTERY

4.5V TO 28V

Minimal Operating Circuit

MAX1710/MAX1711

High-Speed, Digitally Adjusted Step-Down Controllers for Notebook CPUs

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

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 +30V

, 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 (V

+ 0.3V)

SKIP to GND (Note 1).................................-0.3V to (V

+ 0.3V)

DL to PGND................................................-0.3V to (V

+ 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 (T

= +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, 10sec).............................+300°C

BATT

= 4.5V to 28V, includes

load regulation error

SHDN = 0, measured at V+ = 28V, VCC= VDD= 0 or 5V

SHDN = 0

CC,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 SHDN to full I

LIM

(Note 2)

BATT

= 24V, FB = 2V (Note 2)

FB (MAX1710 only) or FBS

FB-FBS or GNDS-GND = 0 to 25mV VCC= 4.5V to 5.5V, V

BATT

= 4.5V to 28V

CONDITIONS

µA<1 5

Shutdown Battery Supply Current

µA<1 5Shutdown Supply Current (VDD)

µA<1 5Shutdown Supply Current (VCC)

µA25 40Quiescent Battery Supply Current

µA<1 5Quiescent Supply Current (VDD)

µA600 950Quiescent Supply Current (VCC)

ns400 500Minimum Off-Time

380 425 470

260 290 320

175 200 225

-1 1

DC Output Voltage Accuracy

TON = REF (400kHz)

4.5 5.5

2 28

Input Voltage Range

TON = GND (550kHz)

140 160 180

On-Time

ms1.7Soft-Start Ramp Time

µA-1 1GNDS Input Bias Current

µA-0.2 0.2FB Input Bias Current

TON = open (300kHz)

mV3Remote Sense Voltage Error mV5Line Regulation Error

UNITMIN TYP MAXPARAMETER

Falling edge, hysteresis = 40mV

REF in regulation

REF

= 0 to 50µA

VCC= 4.5V to 5.5V, no external REF load

V1.6REF Fault Lockout Voltage

µA10REF Sink Current

V0.01Reference Load Regulation

V1.98 2 2.02Reference Voltage

TON = VCC(200kHz)

Note 1: SKIP may 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, V

BATT

= 15V, VCC= VDD= 5V, SKIP = GND, TA= 0°C to +85°C, unless otherwise noted.)

kΩ130 180 240FB Input Resistance (MAX1711)

DAC codes from 1.3V to 2V

-1.2 1.2

LOAD

= 0 to 7A mV9Load Regulation Error

DAC codes from 0.925V to 1.275V

With respect to unloaded output voltage

MAX1710/MAX1711

High-Speed, Digitally Adjusted

Step-Down Controllers for Notebook CPUs

_______________________________________________________________________________________

ELECTRICAL CHARACTERISTICS (continued)

(Circuit of Figure 1, V

BATT

= 15V, VCC= VDD= 5V, SKIP = GND, TA= 0°C to +85°C, unless otherwise noted.)

CONDITIONS UNITMIN TYP MAXPARAMETER

LX to PGND

LX to PGND, ILIM tied to V

From SHDN signal going high

40 50 60

Current-Limit Threshold (Positive Direction, Adjustable)

mV90 100 110

Current-Limit Threshold (Positive Direction, Fixed)

ms10 30

Output Undervoltage Protection Time

%65 70 75

Output Undervoltage Protection Threshold

LX to PGND, TA= +25°C mV-150 -120 -80

Current-Limit Threshold (Negative Direction)

LIM

= 100kΩ

LIM

= 400kΩ 170 200 230

Rising edge, hysteresis = 20mV, PWM disabled below this level

V4.1 4.4

VCCUndervoltage Lockout Threshold

BST-LX forced to 5V Ω5DH Gate-Driver On-Resistance DL, high state Ω5

DL Gate-Driver On-Resistance (Pull-Up)

DL, low state Ω0.5 1.7

DL Gate-Driver On-Resistance (Pull-Down)

DH forced to 2.5V, BST-LX forced to 5V A1

DH Gate-Driver Source/Sink Current

DL forced to 2.5V A3DL Gate-Driver Sink Current DL forced to 2.5V A1DL Gate-Driver Source Current

FB forced 2% above trip threshold µs1.5

Overvoltage Fault Propagation Delay

%10.5 12.5 14.5

Overvoltage Trip Threshold

FB forced 2% below PGOOD trip threshold, falling edge µs1.5PGOOD Propagation Delay

LX to PGND mV3

Current-Limit Threshold (Zero Crossing)

SINK

= 1mA V0.4PGOOD Output Low Voltage High state, forced to 5.5V µA1PGOOD Leakage Current Hysteresis = 10°C °C150Thermal Shutdown Threshold

V2.21 2.25 2.29

0.76 0.8 0.84

With respect to unloaded output voltage (MAX1710)

With respect to unloaded output voltage (MAX1710) (MAX1711) V

DL rising

Dead Time

DH rising 26

SKIP Input Current Logic Threshold

To enable no-fault mode, TA= +25°C -1.5 -0.1

%PGOOD Trip Threshold

Measured at FB with respect to unloaded output voltage, falling edge, hysteresis = 1%

-8 -5 -3 VLogic Input High Voltage

D0–D4, SHDN, SKIP, OVP

2.4 VLogic Input Low Voltage

D0–D4, SHDN, SKIP, OVP

0.8 µALogic Input Current

SHDN, SKIP, OVP

-1 1 µALogic Input Pull-Up Current D0–D4, each forced to GND 3 5 10

(MAX1711)

MAX1710/MAX1711

High-Speed, Digitally Adjusted Step-Down Controllers for Notebook CPUs

4 _______________________________________________________________________________________

%10 15

BATT

= 4.5V to 28V, for all D/A codes, includes load regulation error

CC,VDD

Battery voltage, V+

Measured at VCC, FB forced above the regulation point

Overvoltage Trip Threshold

(Note 2)

BATT

= 24V, FB = 2V (Note 2)

With respect to unloaded output voltage (MAX1710) %

CONDITIONS

65 75

Output Undervoltage Protection Threshold

µA950Quiescent Supply Current (VCC)

ns500Minimum Off-Time

380 470

260 320

175 225

%-1.5 1.5

DC Output Voltage Accuracy

TON = REF (400kHz)

4.5 5.5

2 28

Input Voltage Range

TON = GND (550kHz)

140 180

On-Time

TON = open (300kHz)

UNITMIN TYP MAXPARAMETER

VCC= 4.5V to 5.5V, no external REF load V1.98 2.02Reference Voltage

TON = VCC(200kHz)

LX to PGND, ILIM tied to V

mV85 115

Current-Limit Threshold (Positive Direction, Fixed)

LX to PGND mV

35 65

Current-Limit Threshold (Positive Direction, Adjustable)

LIM

= 100kΩ

LIM

= 400kΩ 160 240

Rising edge, hysteresis = 20mV, PWM disabled below this level

4.1 4.4

VCCUndervoltage Lockout Threshold

D0–D4, SHDN, SKIP, OVP

V2.4Logic Input High Voltage

D0–D4, SHDN, SKIP, OVP

V0.8Logic Input Low Voltage

SHDN, SKIP, OVP

µA-1 1Logic Input Current

D0–D4, each forced to GND µA3 10Logic Input Pull-Up Current

ELECTRICAL CHARACTERISTICS

(Circuit of Figure 1, V

BATT

=15V, V

= VDD= 5V, SKIP = GND, TA= -40°C to +85°C, unless otherwise noted.) (Note 3)

V2.20 2.30

0.75 0.85 V

ELECTRICAL CHARACTERISTICS (continued)

(Circuit of Figure 1, V

BATT

= 15V, VCC= VDD= 5V, SKIP = GND, TA= 0°C to +85°C, unless otherwise noted.)

CONDITIONS

TON logic input high level VVCC- 0.4TON VCCLevel TON logic input upper-mid-range level V3.15 3.85TON Float Voltage TON logic input lower-mid-range level V1.65 2.35TON Reference Level TON logic input low level V0.5TON GND Level TON only, forced to GND or V

µA-3 3TON Logic Input Current

UNITMIN TYP MAXPARAMETER

With respect to unloaded output voltage (MAX1710) (MAX1711)

(MAX1711)

%-1.7 1.7

DAC codes from 1.32V to 2V DAC codes from 0.925V to

1.275V

MAX1710/MAX1711

High-Speed, Digitally Adjusted

Step-Down Controllers for Notebook CPUs

_______________________________________________________________________________________

100

0.01 0.1 1 10

EFFICIENCY vs. LOAD CURRENT

= 2.0V, f = 300kHz)

MAX1710-01

LOAD CURRENT (A)

EFFICIENCY (%)

VIN = 4.5V

VIN = 7V

VIN = 15V

VIN = 24V

100

0.01 0.1 1 10

EFFICIENCY vs. LOAD CURRENT

= 1.6V, f = 300kHz)

MAX1710-02

LOAD CURRENT (A)

EFFICIENCY (%)

VIN = 4.5V

VIN = 24V

VIN = 7V

VIN = 15V

100

0.01 0.1 1 10

EFFICIENCY vs. LOAD CURRENT

= 1.3V, f = 300kHz)

MAX1710-03

LOAD CURRENT (A)

EFFICIENCY (%)

VIN = 4.5V

VIN = 24V

VIN = 15V

VIN = 7V

100

0.01 0.1 1 10

EFFICIENCY vs. LOAD CURRENT

= 1.6V, f = 550kHz)

MAX1710-04

LOAD CURRENT (A)

EFFICIENCY (%)

VIN = 4.5V

VIN = 15V

VIN = 7V

VIN = 24V

100

200

150

300

250

350

0.01 0.1 1 10

FREQUENCY vs. LOAD CURRENT

= 1.6V)

MAX1710-05

LOAD CURRENT (A)

FREQUENCY (kHz)

VIN = 15V, PWM MODE

VIN = 4.5V, SKIP MODE

VIN = 15V, SKIP MODE

TON = OPEN

300

306 304 302

308

310

312

314

316

318

320

0 105 15 20 25 30

FREQUENCY vs. INPUT VOLTAGE

= 7A)

MAX1710-06

INPUT VOLTAGE (V)

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.)

CONDITIONS

Measured at FB with respect to unloaded output voltage, falling edge, hysteresis = 1%

%-8.5 -2.5PGOOD Trip Threshold

SINK

= 1mA V0.4PGOOD Output Low Voltage

High state, forced to 5.5V µA1PGOOD Leakage Current

UNITMIN TYP MAXPARAMETER

ELECTRICAL CHARACTERISTICS (continued)

(Circuit of Figure 1, V

BATT

=15V, V

= VDD= 5V, SKIP = GND, TA= -40°C to +85°C, unless otherwise noted.) (Note 3)

MAX1710/MAX1711

High-Speed, Digitally Adjusted Step-Down Controllers for Notebook CPUs

6 _______________________________________________________________________________________

_____________________________Typical Operating Characteristics (continued)

(7A CPU supply circuit of Figure 1, TA= +25°C, unless otherwise noted.)

0.2

0.1

0.5

0.4

0.3

0.8

0.7

0.6

0.9

0 105 15 20 25 30

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

10.0

10.5

11.0

11.5

12.0

12.5

13.0

13.5

14.0

0 105 15 20 25 30

INDUCTOR CURRENT PEAKS AND

VALLEYS vs. INPUT VOLTAGE

(AT CURRENT-LIMIT POINT)

MAX1710-11

INPUT VOLTAGE (V)

INDUCTOR CURRENT (A)

PEAK

VALLEY

0.2

0.1

0.4

0.3

0.6

0.5

0.7

0 5 15 2510 20 30

NO-LOAD SUPPLY CURRENTS

vs. INPUT VOLTAGE

(SKIP MODE, f = 300kHz)

MAX1710-12

INPUT VOLTAGE (V)

SUPPLY CURRENT (mA)

BATT

0.2

0.1

0.4

0.3

0.6

0.5

0.7

0 10 20 305 15 25

NO-LOAD SUPPLY CURRENTS

vs. INPUT VOLTAGE

(SKIP MODE, f = 550kHz)

MAX1710-13

INPUT VOLTAGE (V)

SUPPLY CURRENT (mA)

BATT

6 4 2

0 105 15 20 25 30

NO-LOAD SUPPLY CURRENTS

vs. INPUT VOLTAGE

(PWM MODE, f = 300kHz)

MAX1710-14

INPUT VOLTAGE (V)

SUPPLY CURRENT (mA)

BAT

6 4 2

0 105 15 20 25 30

NO-LOAD SUPPLY CURRENTS

vs. INPUT VOLTAGE

(PWM MODE, f = 550kHz)

MAX1710-15

INPUT VOLTAGE (V)

SUPPLY CURRENT (mA)

BAT

285

290

295

300

305

310

315

-60 -20-40 0 20 40 60 80 100

FREQUENCY vs. TEMPERATURE

= 15V, VO = 2.0V)

MAX1710-07

TEMPERATURE (°C)

FREQUENCY (kHz)

IO = 7A

IO = 4A

IO = 1A

TON = OPEN

456

460 458

466 464 462

472 470 468

474

-60 0 20-40 -20 40 60 80 100

ON-TIME vs. TEMPERATURE

MAX1710-08

TEMPERATURE (°C)

ON TIME (ns)

IO = 1A

IO = 4A OR 7A

-60 -20-40 0 20 40 60 80 100

CURRENT-LIMIT TRIP POINT

vs. TEMPERATURE

MAX1710-09

TEMPERATURE (°C)

CURRENT TRIP POINT (A)

LIM

= 400kΩ

LIM

= V

LIM

= 100kΩ

10µs/div

LOAD-TRANSIENT RESPONSE

(WITH INTEGRATOR)

VIN = 15V, VO = 1.6V, IO = 0A TO 7A A = V

OUT

, 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 = V

OUT

, AC COUPLED, 50mV/div

B = INDUCTOR CURRENT, 5A/div

MAX1710-17

MAX1710/MAX1711

High-Speed, Digitally Adjusted

Step-Down Controllers for Notebook CPUs

_______________________________________________________________________________________ 7

_____________________________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 = V

OUT

, 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 = V

OUT

, AC COUPLED, 50mV/div B = INDUCTOR CURRENT, 5A/div C = DL, 10V/div

MAX1710-20

500µs/div

START-UP WAVEFORM

A = SHDN B = V

OUT

, 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 = V

OUT

, AC COUPLED, 50mV/div

B = INDUCTOR CURRENT, 5A/div

MAX1710-18

MAX1710/MAX1711

High-Speed, Digitally Adjusted Step-Down Controllers for Notebook CPUs

8 _______________________________________________________________________________________

50µs/div

OUTPUT OVERLOAD WAVEFORM

OUT

= 1.6V

A = V

, AC COUPLED, 2V/div

B = V

OUT

, 0.5V/div

C = INDUCTOR CURRENT, 5A/div

A B

MAX1710-22

5µs/div

LOAD-TRANSIENT RESPONSE

L = 0.7µH, V

OUT

= 1.6V, VIN = 15V, C

OUT

= 47µF (x4), f = 550kHz

A = V

OUT

, AC COUPLED, 100mV/div

B = INDUCTOR CURRENT, 5A/div C = DL, 5V/div

MAX1710-23

CERAMIC C

OUT

5µs/div

SHUTDOWN WAVEFORM

VIN = 15V, V0 = 1.6V, I0 = 7A A = V

OUT

, 0.5V/div B = INDUCTOR CURRENT, 5A/div C = SHDN, 2V/div D = DL, 5V/div

A B C

MAX1710-24

_____________________________Typical Operating Characteristics (continued)

(7A CPU supply circuit of Figure 1, TA= +25°C, unless otherwise noted.)

Pin Description

NAME FUNCTION

5 CC

Integrator Capacitor Connection. Connect a 100pF to 1000pF (470pF typical) capacitor to GND to set the integration time constant.

4 FBS

Feedback Remote-Sense Input, normally connected to V

OUT

directly 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.

3 FB

Fast Feedback Input, normally connected to V

OUT

. 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.

8 TON

On-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, V

= 200kHz.

7 V

Analog Supply Voltage Input for PWM Core, 4.5V to 5.5V. Bypass VCCto GND with a 0.1µF minimum capacitor.

6 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 V

= R

LIM

· 5µA/10.

1 CC

Battery Voltage Sense Connection. V+ is used only for PWM one-shot timing. DH on-time is inversely proportional to V+ input voltage over a range of 2V to 28V.

9 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

SHDN

Shutdown Control Input, active low. SHDN cannot withstand the battery voltage. In shutdown mode, DL is forced to V

in order to enforce overvoltage protection, even when powered down (unless OVP is high).

MAX1710/MAX1711

High-Speed, Digitally Adjusted

Step-Down Controllers for Notebook CPUs

_______________________________________________________________________________________ 9

Standard Application Circuit

The 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 Description

The MAX1710/MAX1711 buck controllers are targeted for low-voltage, high-current CPU power supplies for notebook computers. CPU cores typically exhibit 0 to 10A or greater load steps when the clock is throttled. The proprietary QUICK-PWM pulse-width modulator in the MAX1710/MAX1711 is specifically designed for handling these fast load steps while maintaining a relatively constant operating frequency and inductor operating point over a wide range of input voltages. The QUICKPWM architecture circumvents the poor load-transient timing problems of fixed-frequency current-mode PWMs

Pin Description (continued)

NAME FUNCTION

(MAX1711)

D4 DAC Code Input, MSB, 5µA internal pull-up to VCC(Tables 1 and 2).

13 DL Low-Side Gate-Driver Output, swings 0 to VDD.

12 PGOOD Open-Drain Power-Good Output.

11 GNDS

Ground Remote-Sense Input, normally connected to ground directly at the load. GNDS internally connects to the integrator that fine-tunes the ground offset voltage.

10 GND Analog Ground

14 PGND Power Ground. Also used as the inverting input for the current-limit comparator. 15 V

Supply Voltage Input for the DL gate driver, 4.5V to 5.5V

17 D3 DAC Code Input. 5µA internal pull-up to VCC.

(MAX1710)

OVP

Overvoltage-Protection Disable Control Input (Table 3). GND = normal operation and overvoltage protection active, V

= overvoltage protection disabled.

22 BST

Boost Flying-Capacitor Connection. An optional resistor in series with BST allows the DH pull-up 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. SKIP can also be used to disable both overvoltage and undervoltage protection circuits and clear the fault latch (Figure 6). GND = normal operation, V

= low-noise mode. Do not

leave

SKIP floating.

20 D0 DAC Code Input LSB. 5µA internal pull-up.

19 D1 DAC Code Input. 5µA internal pull-up.

18 D2 DAC Code Input. 5µA internal pull-up.

24 DH High-Side Gate-Driver Output. Swings LX to BST.

23 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 comparator.

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