Rainbow Electronics MAX17409 User Manual

General Description

The MAX17409 is a 1-phase Quick-PWM™ step-down VID power-supply controller for high-performance graphics processors. The Quick-PWM control provides instantaneous response to fast-load current steps. Active voltage positioning reduces power dissipation and bulk output capacitance requirements and allows ideal positioning compensation for tantalum, polymer, or ceramic bulk output capacitors.

The MAX17409 is intended for two different notebook processor core applications: either bucking down the battery directly to create the core voltage, or bucking down the +5V system supply. The single-stage conversion method allows this device 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 higher switching frequency provides the minimum possible physical size.

A slew-rate controller allows controlled transitions between VID codes. A thermistor-based temperature sensor provides programmable thermal protection.

The MAX17409 is available in a 28-pin, 4mm x 4mm TQFN package.

Applications

Graphics Core (GPU) Power Supplies

Voltage-Positioned Step-Down Converters

2-to-4 Li+ Cells Battery to Processor Core Supply Converters

Notebooks/Desktops/Servers

Features

o 1-Phase Quick-PWM Controller

o ±6mV V

OUT

Accuracy Over Line, Load, and

Temperature

o 6-Bit Graphics DAC (12.5mV LSB)

o Active Voltage Positioning with Adjustable Gain

o Accurate Droop and Current Limit

o Remote Output and Ground Sense

o Buffered 2V Reference Output for Offsets

o Power-Good Window Comparator

o Temperature Comparator

o Drives Large Synchronous Rectifier FETs

o 2V to 26V Power Input Range

o Adjustable Switching Frequency (600kHz max)

o Output Overvoltage and Undervoltage Protection

o Soft-Startup and Soft-Shutdown

o Internal Boost Diodes

MAX17409

1-Phase Quick-PWM GPU Controller

________________________________________________________________

Maxim Integrated Products

Pin Configuration

Ordering Information

19-4590; Rev 1; 7/09

For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.

EVALUATION KIT

AVAILABLE

Denotes a lead(Pb)-free/RoHS-compliant package.

EP = Exposed pad.

PART TEMP RANGE PIN-PACKAGE

MAX17409GTI+ -40°C to +105°C 28 TQFN-EP*

Quick-PWM is a trademark of Maxim Integrated Products, Inc.

TOP VIEW

GND

VRHOT

ILIM

CCV

REF

BST

PGNDLXG5

2021 19 17 16 15

SKIP

THRM

SHDN

PWRGD

TON

IMON

GNDS/OFSP

MAX17409

PAD GND

4567

CSN

THIN QFN

CSP

MAX17409

1-Phase Quick-PWM GPU Controller

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(Circuit of Figure 1, VIN= 12V, VDD= VCC= 5V, SHDN = ILIM = VCC, SKIP = GNDS = PGND = GND, VFB= V

CSP

= V

CSN

= 1.05V;

G5–G0 set for 1.05V (G0–G5 = 100110); T

= 0°C to +85°C, unless otherwise specified. Typical values are at TA= +25°C.) (Note 3)

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.

VCC, VDDto GND .....................................................-0.3V to +6V

G0–G5 to GND .........................................................-0.3V to +6V

CSP, CSN to GND ....................................................-0.3V to +6V

ILIM, THRM, VRHOT, PWRGD to GND ....................-0.3V to +6V

SKIP to GND.............................................................-0.3V to +6V

CCV, FB, IMON, REF to GND.....................-0.3V to (V

+ 0.3V)

SHDN to GND (Note 1)...........................................-0.3V to +30V

TON to GND ...........................................................-0.3V to +30V

GNDS/OFSP, PGND to GND (Note 2) ...................-0.3V to +0.3V

Internal Driver (Note 2)

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

+ 0.3V)

BST to GND .........................................................-0.3V to +36V

LX to BST...............................................................-6V to +0.3V

BST to V

..........................................................-0.3V to +30V

DH to LX .................................................-0.3V to (V

BST

+ 0.3V)

Continuous Power Dissipation (T

= +70°C) 28-Pin 4mm x 4mm TQFN

(derate 21.3mW/°C above +70°C) ............................1702mW

Operating Temperature Range .........................-40°C to +105°C

Junction Temperature......................................................+150°C

Storage Temperature Range .............................-65°C to +165°C

Lead Temperature (soldering, 10s) .................................+300°C

Note 1: SHDN might be forced to 12V for the purpose of debugging prototype breadboards using the no-fault test mode, which dis-

ables fault protection.

Note 2: Measurements valid using a 20MHz bandwidth limit.

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

PWM CONTROLLER

Input Voltage Range VCC, VDD 4.5 5.5 V

DC Output-Voltage Accuracy

Line Regulation Error VCC = 4.5V to 5.5V, VIN = 4.5V to 26V 0.1 %

GNDS Input Range -200 +200 mV

GNDS/OFSP Gain A

GNDS/OFSP Input Bias Current I

REF Voltage V

Dynamic VID Slew-Rate Accuracy 11.0 12.5 14.0 mV/µs

Soft-Start/Soft-Shutdown Slew-Rate Accuracy

On-Time (Note 5) t

Minimum Off-Time t TON Shutdown Input Current SHDN = GND, VIN = 26V, VCC = VDD = 0 or 5V 0.01 0.1 µA

Measured at FB with respect to GNDS; inc lude s load-regulation error (Note 4)

V

GNDS

-2 +2 µA

GNDS

REF

1.248 1.56 1.872 mV/µs

OFF(MIN)

Measured at DH (Note 5) 300 375 ns

/V

OUT

GNDS

VCC = 4.5V to 5.5V, I

= 0 to 1mA 1.97 2.000 2.02

REF

VIN = 12V, VFB = 1.2V

, -200mV  V

= 100µA 1.98 2.000 2.02

REF

-6 +6 mV

 +200mV 0.97 1.00 1.03 V/V

GNDS

= 96.75k 142 167 192

TON

= 200k 300 333 366

TON

= 303.25k 425 500 575

TON

MAX17409

1-Phase Quick-PWM GPU Controller

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

(Circuit of Figure 1, VIN= 12V, VDD= VCC= 5V, SHDN = ILIM = VCC, SKIP = GNDS = PGND = GND, VFB= V

CSP

= V

CSN

= 1.05V;

G5–G0 set for 1.05V (G0–G5 = 100110); T

= 0°C to +85°C, unless otherwise specified. Typical values are at TA= +25°C.) (Note 3)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

BIAS CURRENTS

Quie scent Supply Current (VCC) I

Quie scent Supply Current (VDD) I

Shutdown Supply C urrent (VCC) Measured at VCC, SHDN = GND, TA = +25°C 0.01 1 µA

Shutdown Supply C urrent (VDD) Measured at VDD, SHDN = GND, TA = +25°C 0.01 1 µA

FAULT PROTECTION

Output Overvoltage Protect ion Threshold

Output Overvoltage Propagation Delay

Output Undervoltage Protection Threshold

Output Undervoltage Propagation Dela y

PWRGD Startup Delay

PWRGD Threshold

PWRGD Transition Blanking Time

PWRGD Delay

PWRGD Output Low Voltage I

PWRGD Leakage Current High state, PWRGD forced to 5V 1 µA

VCC Undervoltage-Lockout Threshold

CSN Discharge Resistance in UVLO

OVP

UVP

BLANK

UVLO(VCC)

Measured at VCC, SKIP = 5V, FB forced above the regulation point

Measured at VDD, SKIP = 0V, FB forced above the regulation point, T

Skip mode after output reaches the regulation voltage or PWM mode; measured at FB with respect to unloaded output vo ltage

Soft-start, soft-shutdown, skip mode, and output have not reached the regulation voltage; mea sured at FB

Min imum OVP threshold; measured at FB 0.8

FB forced 25mV above trip thresho ld 10 µs

Measured at FB with respect to unloaded output vo ltage

FB forced 25mV below trip threshold 10 µs

Measured at startup from the time when SHDN goes high

Measured at FB with respect to unloaded output voltage, 15mV hysteresis (typ)

Measured from the time when FB reaches the target voltage (Note 4) based on the slew rate FB forced 25mV out side the PWRGD trip thresholds

= 3mA 0.4 V

SINK

Risi ng edge, 50mV typical hysteresis, controller disabled below this level

= VDD = 4.0V 8 

Lower threshold, falling edge (undervoltage)

Upper threshold, rising edge (overvoltage)

= +25°C

1.5 3 mA

0.02 1 µA

250 300 350 mV

1.45 1.50 1.55

-450 -400 -350 mV

3 5 8 ms

-350 -300 -250

+150 +200 +250

20 µs

10 µs

4.05 4.25 4.48 V

ELECTRICAL CHARACTERISTICS (continued)

(Circuit of Figure 1, VIN= 12V, VDD= VCC= 5V, SHDN = ILIM = VCC, SKIP = GNDS = PGND = GND, VFB= V

CSP

= V

CSN

= 1.05V;

G5–G0 set for 1.05V (G0–G5 = 100110); T

= 0°C to +85°C, unless otherwise specified. Typical values are at TA= +25°C.) (Note 3)

MAX17409

1-Phase Quick-PWM GPU Controller

4 _______________________________________________________________________________________

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

THERMAL COMPARATOR AND PROTECTION

VRHOT Trip Threshold

VRHOT Delay t

VRHOT Output On-Resistance R VRHOT Leakage Current I

THRM Input Leakage I

Thermal-Shutdown Threshold T

VRHOT

THRM

SHDN

Measured at THRM with respect to V falling edge; typical hysteresis = 100mV

THRM forced 25mV below the VRHOT trip threshold; falling edge

Low state 2 8  High state, VRHOT forced to 5V, TA = +25°C 1 µA

= 0 to 5V, TA = +25°C -100 +100 nA

THRM

Typical hysteresis = 15°C 160 °C

;

29.2 30 30.8 %

10 µs

VALLEY CURRENT LIMIT AND DROOP

- V

Current-Limit Threshold Voltage (Positive Adjustable)

Current-Limit Threshold Voltage (Positive Default)

Current-Limit Threshold Voltage (Negative) Accuracy

Current-Limit Threshold Voltage (Zero Crossing)

CSP, CS N Comm on- Mode Input Range

LIMIT

ILIM = V

LIMIT(NEG) VCSP

ZERO VPGND

0 1.9 V

CSP

- V

REF

CSN

CSP

- V

CSN

, V

- V

, nominally -125% of V

CSN

- VLX 1 mV

= 100mV 7 10 13

ILIM

- V

= 500mV 45 50 55

ILIM

20 22.5 25 mV

LIMIT

-4 +4 mV

CSP, CSN Input Current TA = +25°C -0.2 +0.2 µA

ILIM Input Current TA = +25°C -100 +100 nA

Droop Amplifier (GMD) Offset (V

Droop Amplifier (GMD) Transconductance

- V

CSP

I

/(V

) at IFB = 0 -0.75 +0.75 mV

CSN

- V

CSN

);

CSP

FB = CSN = 0.45V to 2.0V, and (V

CSP

- V

) = -15.0mV to +15.0mV

CSN

592 600 608 µS

GATE DRIVERS

DH Gate-Driver On-Resistance R

DL Gate-Driver On-Resistance R

DH Gate-Driver Source Current I

DH(S OURC E)

DH Gate-Driver Sink Current I

DL Gate-Driver Source Current I

DL(SOURCE)

DL Gate-Driver Sink Current I

Internal BST Switch On-Resistance

ON(DH)

ON(DL)

DH(S INK)

DL(S INK)

BST IBST

BST - LX forced to 5V

High state (pullup) 0.7 2.0

Low state (pulldown) 0.25 0.7

DH forced to 2.5V, BST - LX forced to 5V 2.2 A

DH forced to 2.5V, BST - LX forced to 5V 2.7 A

DL forced to 2.5V 2.7 A

DL forced to 2.5V 8 A

= 10mA, VDD = 5V 10 20 

High state (pullup) 0.9 2.5

Low state (pulldown) 0.7 2.0



ELECTRICAL CHARACTERISTICS (continued)

(Circuit of Figure 1, VIN= 12V, VDD= VCC= 5V, SHDN = ILIM = VCC, SKIP = GNDS = PGND = GND, VFB= V

CSP

= V

CSN

= 1.05V;

G5–G0 set for 1.05V (G0–G5 = 100110); T

= 0°C to +85°C, unless otherwise specified. Typical values are at TA= +25°C.) (Note 3)

MAX17409

1-Phase Quick-PWM GPU Controller

_______________________________________________________________________________________ 5

ELECTRICAL CHARACTERISTICS

(Circuit of Figure 1, VIN= 12V, VDD= VCC= 5V, SHDN = ILIM = VCC, SKIP = GNDS = PGND = GND, VFB= V

CSP

= V

CSN

= 1.05V;

G5–G0 set for 1.05V (G0–G5 = 100110); T

= -40°C to +105°C, unless otherwise specified.) (Note 3)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

CURRENT MONITOR

Current-Monitor Transconductance G

Current-Monitor Offset Referred to V(CSP,CSN)

IMON Clamp Voltage V

m(IMON)IIMON

IMON

/(V

- V

), V

CSP

CSN

= 0 -1.0 +1.0 mV

IMON

= -1.0mA 1.05 1.10 1.15 V

IMON

= 0.5V to 1.0V 4.9 5.0 51 mS

CSN

LOGIC AND I/O

Logic-Input High Voltage V

Logic-Input Low Voltage V

Low-Voltage Logic-Input High Voltage

Low-Voltage Logic-Input Low Voltage

IHLV

ILLV

SHDN, SKIP 2.3 V

SHDN, SKIP 1.0 V

G0–G5 0.67 V

G0–G5 0.33 V

Logic-Input Current TA = +25°C, S HDN, SKIP, G0–G5 = 0 or 5V -1 +1 µA

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

PWM CONTROLLER

Input Voltage Range VCC, VDD 4.5 5.5 V

DC Output-Voltage Accuracy

Measured at FB with respect to GNDS, inc lude s load regulation error (Note 4)

-10 +10 mV

GNDS Input Range For positive offset and remote-sen se errors -200 +200 mV

GNDS/OFSP Gain A

REF Voltage V

GNDS

REF

V

/V

OUT

= 4.5V to 5.5V, I

= 0 to 1mA 1.95 2.03

REF

GNDS

, -200mV  V

= 100µA 1.97 2.03

REF

 +200mV 0.95 1.05 V/V

GNDS

Dynamic VID Slew-Rate Accuracy 10 15 mV/µs

Soft-Start/Soft-Shutdown Slew-Rate Accuracy

On-Time (Note 5) t

Minimum Off-Time t

1.248 1.872 mV/µs

= 96.75k 142 192

TON

OFF(MIN)

VIN = 12V, VFB = 1.2V

Measured at DH (Note 5) 400 ns

= 200k 300 366

TON

= 303.25k 425 575

TON

BIAS CURRENTS

Quie scent Supply Current (VCC) I

Measured at VCC, SKIP = 5V, FB forced above the regulation point

3 mA

MAX17409

1-Phase Quick-PWM GPU Controller

6 _______________________________________________________________________________________

ELECTRICAL CHARACTERISTICS (continued)

(Circuit of Figure 1, VIN= 12V, VDD= VCC= 5V, SHDN = ILIM = VCC, SKIP = GNDS = PGND = GND, VFB= V

CSP

= V

CSN

= 1.05V;

G5–G0 set for 1.05V (G0–G5 = 100110); T

= -40°C to +105°C, unless otherwise specified.) (Note 3)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

FAULT PROTECTION

Output Overvoltage-Protection Threshold

Output Undervoltage-Protection Threshold

PWRGD Startup Delay

PWRGD Threshold

PWRGD Output Low Voltage I

VCC Undervoltage-Lockout Threshold

THERMAL COMPARATOR AND PROTECTION

VRHOT Trip Threshold

VRHOT Output On-Resistance R

VALLEY CURRENT LIMIT AND DROOP

Current-Limit Threshold Voltage (Positive Adjustable)

Current-Limit Threshold Voltage (Positive Default)

Current-Limit Threshold Voltage (Negative) Accuracy

CSP, CS N Comm on- Mode Input Range

Droop Amplifier GMD) Offset (V

Droop Amplifier (GMD) Transconductance

Skip mode after output reaches the regulation voltage or PWM mode; measured at FB with respect to unloaded

OVP

output vo ltage

Soft-start, soft-shutdown, skip mode, and output have not reached the regulation voltage, mea sured at FB

UVP

Measured at FB with respect to unloaded output vo ltage

Measured at startup from the time when SHDN goes high

Measured at FB with respect to

Lower threshold, falling edge (undervoltage)

unloaded output

Upper threshold, rising edge (overvoltage)

UVLO(VCC)

voltage; 15mV hysteresis (typ)

= 3mA 0.4 V

SINK

Risi ng edge, 50mV typical hysteresis, controller disabled below this level

Measured at THRM with respect to V falling edge; typical hysteresis = 100mV

VRHOT

LIMIT

LIMIT(NEG) VCSP

Low state 8 

- V

CSP

ILIM = V

- V

CSP

- V

REF

CSN

, V

, nominally -125% of V

CSN

= 100mV 7 13

ILIM

- V

= 500mV 45 55

ILIM

20 25 mV

LIMIT

0 1.9 V

- V

CSP

/(V

I

) at IFB = 0 -1.0 +1.0 mV

CSN

- V

CSN

);

CSP

FB = CSN = 0.45V to 2.0V, and (V

CSP

- V

) = -15.0mV to +15.0mV

CSN

250 350 mV

1.45 1.55 V

-450 -350 mV

3 8 ms

-350 -250 mV

+150 +250 mV

4.0 4.5 V

;

29.2 30.8 %

-5 +5 mV

588 612 µS

MAX17409

1-Phase Quick-PWM GPU Controller

_______________________________________________________________________________________ 7

ELECTRICAL CHARACTERISTICS (continued)

(Circuit of Figure 1, VIN= 12V, VDD= VCC= 5V, SHDN = ILIM = VCC, SKIP = GNDS = PGND = GND, VFB= V

CSP

= V

CSN

= 1.05V;

G5–G0 set for 1.05V (G0–G5 = 100110); T

= -40°C to +105°C, unless otherwise specified.) (Note 3)

Note 3: Limits are 100% production tested at TA= +25°C. Maximum and minimum limits over temperature are guaranteed by design

and characterization.

Note 4: The equation for the target voltage V

TARGET

is:

TARGET

= the slew-rate-controlled version of V

DAC

, where V

DAC

= 0 for shutdown, V

DAC

= V

VID

otherwise (the V

VID

voltages for all possible VID codes are given in Table 4). In pulse-skipping mode, the output rises by approximately 1.5% when transitioning from continuous conduction to no load.

Note 5: On-time and minimum off-time specifications are measured from 50% to 50% at the DH pin, with LX forced to 0V, BST forced

to 5V, and a 500pF capacitor from DH to LX to simulate external MOSFET gate capacitance. Actual in-circuit times might be different due to MOSFET switching speeds.

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

GATE DRIVERS

DH Gate-Driver On-Resistance R

DL Gate-Driver On-Resistance R

Internal BST Switch On-Resistance

CURRENT MONITOR

Current-Monitor Transconductance G

Current-Monitor Offset Referred to V(CSP,CSN)

IMON Clamp Voltage V

LOGIC AND I/O

Logic-Input High Voltage V

Logic-Input Low Voltage V

Low-Voltage Logic-Input High Voltage

Low-Voltage Logic-Input Low Voltage

ON(DH)

ON(DL)

BST IBST

m(IMON)IIMON

IMON IIMON

IHLV

ILLV

BST - LX forced to 5V

High state (pullup) 2.0

Low state (pulldown) 0.7

= 10mA, VDD = 5V 20 

IMON

SHDN, SKIP 2.3 V SHDN, SKIP 1.0 V

G0–G5 0.67 V

G0–G5 0.33 V

/(V

CSP

= 0 -1.0 +1.0 mV

= -1.0mA 1.05 1.15 V

High state (pullup) 2.5

Low state (pulldown) 2.0

- V

) V

CSN

= 0.5V to 1.0V 4.9 5.1 mS

CSN



MAX17409

1-Phase Quick-PWM GPU Controller

8 _______________________________________________________________________________________

Typical Operating Characteristics

(Circuit of Figure 1, VIN= 12V, VCC= VDD= 5V, SHDN = VCC, G0–G5 set for 1.05V (G0–G5 = 100110), TA= +25°C, unless otherwise specified.)

100

EFFICIENCY (%)

0.01 100

0.9V OUTPUT EFFICIENCY vs. LOAD CURRENT

12V

20V

SKIP MODE PWM MODE

1010.1

LOAD CURRENT (A)

MAX17409 toc01

0.92

0.91

0.90

OUTPUT VOLTAGE (V)

0.89

0.88

0.9V OUTPUT VOLTAGE vs. LOAD CURRENT

SKIP MODE

PWM MODE

016

LOAD CURRENT (A)

12 14108642

MAX17409 toc02

SWITCHING FREQUENCY

vs. LOAD CURRENT

350

VIN = 12V

300

250

200

150

100

SWITCHING FREQUENCY (kHz)

0.01 100 LOAD CURRENT (A)

0.8125V OUTPUT

VOLTAGE DISTRIBUTION

+85°C

+25°C

SAMPLE PERCENTAGE (%)

0.8085

0.8095

0.8075 OUTPUT VOLTAGE (V)

0.8105

SAMPLE SIZE = 100

0.8115

0.8125

0.8135

0.8145

SKIP MODE PWM MODE

1010.1

0.8155

0.8165

0.8175

MAX17409 toc03

MAX17409 toc05

NO-LOAD SUPPLY CURRENT

vs. INPUT VOLTAGE

100

0.1

SWITCHING FREQUENCY (kHz)

0.01 514

ICC + I

INPUT VOLTAGE (V)

TRANSCONDUCTANCE

(FB)

ICC + I

SKIP MODE PWM MODE

12 1311109876

MAX17409 toc04

DISTRIBUTION

+85°C

+25°C

SAMPLE PERCENTAGE (%)

592

594

590

TRANSCONDUCTANCE (µS)

596

SAMPLE SIZE = 100

598

600

602

604

606

608

MAX17409 toc06

610

MAX17409

1-Phase Quick-PWM GPU Controller

_______________________________________________________________________________________

Typical Operating Characteristics (continued)

(Circuit of Figure 1, VIN= 12V, VCC= VDD= 5V, SHDN = VCC, G0–G5 set for 1.05V (G0–G5 = 100110), TA= +25°C, unless otherwise specified.)

SAMPLE PERCENTAGE (%)

100

TRANSCONDUCTANCE

(IMON)

DISTRIBUTION

MAX17409 toc07

0.95V

4.96

4.98

SAMPLE SIZE = 100

5.00

5.02

5.04

5.06

5.08

5.10

+85°C

+25°C

4.92

4.94

4.90 TRANSCONDUCTANCE (mS)

LOAD-TRANSIENT RESPONSE

(PWM MODE)

SOFT-START WAVEFORM

A. SHDN, 5V/div

, 10A/div

B. I

, 500mV/div

C. V

OUT

MAX17409 toc10

1ms/div

MAX17409 toc08

D. PWRGD, 5V/div E. DL, 5V/div

= 0A, SKIP MODE

OUT

SOFT-SHUTDOWN WAVEFORM

0.95V

A. SHDN, 5V/div

, 10A/div

B. I

, 500mV/div

C. V

OUT

LOAD-TRANSIENT RESPONSE

(SKIP MODE)

100µs/div

MAX17409 toc11

MAX17409 toc09

D. PWRGD, 5V/div E. DL, 5V/div

= 0A, SKIP MODE

OUT

0.95V

A. V B. I

OUT

, 20A/div

, 50mV/div

20µs/div

C. LX, 10V/div

= 1A - 11A

OUT

0.95V

A. V B. I

OUT

, 20A/div

, 50mV/div

20µs/div

C. LX, 10V/div

= 1A - 11A

OUT

MAX17409

1-Phase Quick-PWM GPU Controller

10 ______________________________________________________________________________________

Pin Description

PIN NAME FUNCTION

Current Monitor Output. The MAX17409 IMON output sources a current that is directl y proportional to the current-sen se vo ltage as defined by:

1 IMON

2 GNDS/OFSP

3 FB

4 CSN

5 CSP

6 SKIP

= G

IMON

where G

The IMON current is unidirectional (sources current out of IMON only) for positive current-sense values. For negative current-sense vo ltages, the IMON current is zero.

Connect an e xternal resistor between IMON and GNDS to create the desired IMON gain based on the following equation:

where I

LOAD(MAX)

The IMON voltage is internall y clamped to 1.1V. The transconductance amplifier and voltage clamp are internally compensated, so IMON cannot drive large external capacitance values. To filter the IMON signal, use an RC filter as shown in Figure 1.

Remote Ground-Sense Input/Positi ve Offset Input. Connect directl y to the ground-sense pin or ground connect ion of the load. GNDS internally connects to a transconductance amplifier that adjusts the feedback vo ltage—compen sating for voltage drops between the regulator’s ground and the processor’s ground.

Remote-Sense Feedback Input and Voltage-Position ing Transconductance Amplifier Output. Connect resistor R pin of the load) for best accurac y and to set the steady-state droop based on the voltagepositioning gain requirement:

where R current-sen se resi stance w ith respect to CSP to CSN current-sen se inputs. See the Current Sense section for details on designing with sense resistors or inductor DCR sensi ng.

Shorting FB directly to the output effectively disab les voltage posit ioning, but impacts the stability requirement s. Designs that disable vo ltage positioning require a h igher minimum output capacitance ESR to maintain stabil ity (see the Output Capacitor Selection section).

FB enters a high-impedance state in shutdown.

Negative Inductor Current-Sense Input. Connect CSN to the negative terminal of the inductor current-sen sing resistor or directly to the negati ve terminal of the inductor if the loss less DCR sen si ng method is used (see Figure 3).

Positive Inductor Current-Sense Input. Connect CSP to the positive terminal of the inductor currentsen si ng resistor or direct ly to the pos itive terminal of the filtering capacitor used when the loss less DCR sensing method is used (see Figure 3).

Pulse-Skipping Control Input. The SKIP signal indicate s the power usage and sets the operating mode of the MAX17409. When the system forces SKIP high, the MAX17409 immediately enters automatic pulse-skipping mode. The controller returns to continuous forced-PWM mode when SKIP is pulled low and the output is in regulat ion. SKIP determines the operating mode and outputvoltage transition slew rate as shown in the truth table below:

SKIP 0 Normal slew rate, forced-PWM mode 1 Normal slew rate, s kip mode

The SKIP state is ignored during soft-start and shutdown. The MAX17409 alway s uses pulsesk ipping mode during startup to ensure a monotonic power-up. During shutdown, the controller always uses forced-PWM mode so the output can be actively discharged.

DROOP_DC

Functionality

m(IMON)

= 5mS (typ).

= 1.0V/(I

IMON

is the maximum load current, and R

between FB and the output remote-sense pin (or Kelvi n-sensed to the supply

is the desired voltage-positioning slope, GMD = 600µS (typ), and R

LOAD(MAX)

= R

DROO P

m(IMON)

/(R

x (V

x R

SENSE

CSP

SENSE

- V

)

CSN

x G

is the current-sense voltage.

x GMD)

m(IMON)

)

SENSE

is the

+ 22 hidden pages

Rainbow Electronics MAX17409 User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual