Rainbow Electronics MAX1813 User Manual

General Description

The MAX1813 step-down controller is intended for core CPU DC-DC converters in notebook computers. The controller features a dynamically adjustable output (5bit DAC), ultra-fast transient response, high DC accuracy, and high efficiency necessary for leading-edge CPU core power supplies. Maxim’s proprietary QuickPWM™ 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.

The MAX1813 is designed specifically for CPU core applications requiring a voltage-positioned supply. The voltage-positioning input (VPCS), combined with a high-DC-accuracy control loop, is used to implement a power supply that modifies its output set point in response to the load current. This arrangement decreases full-load power dissipation and reduces the required number of output capacitors.

The output voltage can be dynamically adjusted through the 5-bit digital-to-analog converter (DAC) inputs over a 0.600V to 2V range. The MAX1813 includes an internal multiplexer that selects between three different DAC code settings. The first two inputs are controlled by five digital input pins (D0–D4). The third input is used for the suspend mode and controlled by two 4-level input pins (S0, S1). Output voltage transitions are accomplished with a proprietary precision slew-rate control that minimizes surge currents to and from the battery while guaranteeing “just-in-time” arrival at the new DAC setting.

The MAX1813’s 28V input range enables single-stage buck conversion from high-voltage batteries for the maximum possible efficiency. Alternatively, the controller’s high-frequency capability combined with twostage conversion (stepping down the +5V system supply instead of the battery) allows the smallest possible physical size.

The MAX1813 is available in a 28-pin QSOP package.

Applications

Notebook Computers

(Intel IMVP–II™/Coppermine™)

Docking Stations

CPU Core Supply

Single-Stage (BATT to V

CORE

) Converters

Two-Stage (+5V to V

CORE

) Converters

Features

♦ High-Efficiency Voltage Positioning

♦ Quick-PWM Architecture

♦ ±1% V

OUT

Accuracy Over Line

♦ Adjustable Output Slew Rate

♦ 0.600V to 2V Adjustable Output Range (5-Bit DAC)

♦ 2V to 28V Battery Input Range

♦ 200/300/600/1000kHz Switching Frequency

♦ Output Undervoltage and Overvoltage Protection

♦ Drives Large Synchronous-Rectifier MOSFETs

♦ ±20% Accurate Current-Limit

♦ 10µA Shutdown Supply Current

♦ 2V ±1% Reference Output

♦ Power-Good (PGOOD) Indicator

♦ Small 28-Pin QSOP Package

MAX1813

Dynamically-Adjustable, Synchronous Step-Down

Controller with Integrated Voltage Positioning

________________________________________________________________ Maxim Integrated Products 1

Ordering Information

19-2010; Rev 0; 4/01

For price, delivery, and to place orders, please contact Maxim Distribution at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.

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

Coppermine and IMVP-

ΙΙ

are trademarks of Intel Corp.

Typical Operating Circuit appears at end of data sheet.

BST

PGND

CODE

ZMODE

SUS

GND

PGOOD

ILIM

REF

TON

TIME

SKP/SDN

VPCS

V+

QSOP

TOP VIEW

MAX1813

Pin Configuration

PART TEMP. RANGE PIN-PACKAGE

MAX1813EEI -40°C to +85°C 28 QSOP

MAX1813

Dynamically-Adjustable, Synchronous Step-Down Controller with Integrated Voltage Positioning

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(Circuit of Figure 1, V+ = +15V, VCC= VDD= 5V, VPCS = ZMODE = GND = PGND, SKP/SDN = CODE = VCC, V

OUT

set to 1.5V,

= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.)

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.

Note 1: SKP/SDN may be forced to 12V, temporarily exceeding the absolute maximum rating, for the purpose of debugging proto-

type breadboards, using the no-fault test mode.

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

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

PGND to GND.....................................................................±0.3V

D0–D4, CODE, ZMODE, SUS, PGOOD to GND ......-0.3V to +6V

SKP/SDN to GND (Note 1) .....................................-0.3V to +16V

ILIM, FB, CC, REF,

TON, TIME, S0, S1 to GND......................-0.3V to (V

+ 0.3V)

VPCS to GND ............................................................-2V to +30V

DL to PGND................................................-0.3V to (VDD+ 0.3V)

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

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

BST

+ 0.3V)

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

REF Short Circuit to GND ...........................................Continuous

Continuous Power Dissipation (TA= +70°C)

28-Pin QSOP (derate 10.8mW/°C above +70°C)..........860mW

Operating Temperature Range ...........................-40°C to +85°C

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

Storage Temperature Range .............................-65°C to +150°C

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

)

PWM CONTROLLER

Input Voltage Range

DC Output Voltage Accuracy (Notes 2, 3)

VPCS Input Bias Current I

VPCS Transconductance G

VPCS Linear Input Range ±100 mV

FB Input Resistance R

TIME Frequency Accuracy

ILIM Input Leakage Current I

On-Time (Note 4) t

Minimum Off-Time (Note 4) t

BIAS AND REFERENCE

Quiescent Supply Current (VCC)I

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Battery voltage, V+ 2 28

VPS

ILIM

OFF(MIN

, V

V+ = 4.5V to 28V, VPCS = GND, DAC codes from 0.925V to 2.0V

V+ = 4.5V to 28V, VPCS = GND, DAC codes from 0.700V to 0.900V

V+ = 4.5V to 28V, VPCS = GND, DAC codes from 0.600V to 0.675V

= 0 or 28V -1 +1 µA

VPCS

= 0 to -100mV 18 20 22 µS

VPCS

38kHz nominal, R

150kHz nominal, R

380kHz nominal, R

= 0 or 5.0V 0.01 100 nA

ILIM

V+ = 5.0V, VFB = 1.2V TON = GND 250 270 290

V+ = 12V, VFB = 1.2V

TON = REF, open, or V

TON = GND 300 375

Measured at VCC, FB forced above the regulation point

= 470kΩ -12 +12

TIME

= 120kΩ -8 +8

TIME

= 47kΩ -12 +12

TIME

TON = REF 165 190 215

TON = open 320 355 390

TON = V

4.5 5.5

-1 +1

-1.5 +1.5

-1.83 +1.83

115 180 265 kΩ

465 515 563

400 500

1.4 2.5 mA

MAX1813

Dynamically-Adjustable, Synchronous Step-Down

Controller with Integrated Voltage Positioning

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

(Circuit of Figure 1, V+ = +15V, VCC= VDD= 5V, VPCS = ZMODE = GND = PGND, SKP/SDN = CODE = VCC, V

OUT

set to 1.5V,

= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.)

Quiescent Supply Current (VDD)I

Quiescent Supply Current (V+) I+ Measured at V+ 25 40 µA

Shutdown Supply Current (VCC) SKP/SDN = GND 2 5 µA

Shutdown Supply Current (VDD) SKP/ SDN = GND <1 5 µA Shutdown Supply Current (V+) SKP/SDN = GND, VCC = VDD = 0 or 5V <1 5 µA

Reference Voltage V

REF Fault Lockout Voltage Falling edge, 1% hysteresis 1.5 1.6 1.7 V

FAULT PROTECTION

Output Overvoltage Fault Preset Threshold

Output Overvoltage Fault Propagation Delay

Output Undervoltage Fault Threshold

Output Undervoltage Fault Propagation Delay

Output Undervoltage FaultBlanking Time

Current-Limit Threshold (Positive, Default)

Current-Limit Threshold (Positive, Adjustable)

Negative Current-Limit Threshold

Zero-Crossing Current-Limit Threshold

Thermal Shutdown Threshold Rising temperature, hysteresis = 15°C 160 °C

VCC Undervoltage Lockout Threshold

PGOOD Lower Trip Threshold

PGOOD Upper Trip Threshold

PGOOD Propagation Delay

PGOOD Output Low Voltage I PGOOD Leakage Current High state, forced to 5.5V 1 µA

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

REF

OVP

ITH

Measured at VDD, FB forced above the regulation point

VCC = 4.5V to 5.5V, -40µA ≤ I

Measured at FB

FB forced to 2% above trip threshold 1.5 µs

With respect to unloaded output voltage 60 70 80 %

FB forced to 2% below trip threshold 10 µs

From SKP/SDN signal going high, clock speed set by R

- V

GND

- V

GND

- V

GND

- V

GND

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

Measured at FB with respect to unloaded output voltage, falling edge

Measured at FB with respect to unloaded output voltage, rising edge

Falling edge, FB forced 2% below or above PGOOD trip threshold

= 1mA 0.4 V

SINK

TIME

, ILIM = V

VPCS

, with respect to V

VPCS

≤ +40µA 1.98 2 2.02 V

REF

CODE = GND 2.20 2.25 2.30

CODE = V

= 0.5V 40 50 60

ILIM

= 2V (REF) 143 200 265

ILIM

, ILIM =

ITH

1.95 2.00 2.05

40 50 60 mV

-72 -56 -40 mV

4.05 4.45 V

-15 -12.5 -10.5 %

81012%

<1 5 µA

256 clks

5mV

1.5 µs

MAX1813

Dynamically-Adjustable, Synchronous Step-Down Controller with Integrated Voltage Positioning

4 _______________________________________________________________________________________

ELECTRICAL CHARACTERISTICS (continued)

(Circuit of Figure 1, V+ = +15V, VCC= VDD= 5V, VPCS = ZMODE = GND = PGND, SKP/SDN = CODE = VCC, V

OUT

set to 1.5V,

= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.)

)

GATE DRIVERS

DH Gate Driver On-Resistance R

DL Gate Driver On-Resistance R

DH Gate Driver Source/Sink Current

DL Gate Driver Sink Current I

DL Gate Driver Source Current I

Dead Time

LOGIC AND I/O

Logic Input High Voltage V

Logic Input Low Voltage V

DAC Z-Mode Programming Resistor, Low

DAC Z-Mode Programming Resistor, High

D0−D4, CODE Pull Up/Down

Logic Input Current

4-Level Logic Input High (VCC) TON (200kHz operation), S0, S1

4-Level Logic Input UpperMiddle (Float)

4-Level Logic Input LowerMiddle (REF)

4-Level Logic Low (GND) TON (1000kHz operation), S0, S1 0.5 V

SKP/SDN High Input Level (Skip Mode)

SKP/SDN Float Input Level (Forced-PWM Mode)

SKP/SDN Low Input Level (Shutdown Mode)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

ON (D H ) VBST

ON(DL

- VLX forced to 5V 1.2 3.5 Ω

High state (pull up) 1.3 3.5

Low state (pull down) 0.4 1.0

DH forced to 2.5V, V

DL forced to 5V 4.0 A

DL forced to 2.5V 1.3 A

DL rising 35

DH rising 26

D0−D4, CODE, SUS, ZMODE; VCC = 4.5V to 5.5V

D0−D4, 0 to 0.4V or 2.6V to 5.5V applied to the resistor, ZMODE = CODE = GND or ZMODE = CODE = V

Entering impedance mode

D0−D4, CODE = V

SUS, ZMODE = GND or V

TON (300kHz operation), S0, S1 2.8 3.85 V

TON (600kHz operation), S0, S1 1.65 2.35 V

- VLX forced to 5V 2.0 A

BST

2.4 V

95 kΩ

Pull up 40

Pull down 8

-1 +1

0.4

2.8 6.0 V

1.4 2.2 V

Ω

0.8 V

1.05 kΩ

kΩ

µA

0.5 V

MAX1813

Dynamically-Adjustable, Synchronous Step-Down

Controller with Integrated Voltage Positioning

_______________________________________________________________________________________ 5

ELECTRICAL CHARACTERISTICS (continued)

(Circuit of Figure 1, V+ = +15V, VCC= VDD= 5V, VPCS = ZMODE = GND = PGND, SKP/SDN = CODE = VCC, V

OUT

set to 1.5V,

= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.)

ELECTRICAL CHARACTERISTICS

(Circuit of Figure 1, V+ = +15V, VCC= VDD= 5V, VPCS = ZMODE = GND = PGND, SKP/SDN = CODE = VCC, V

OUT

set to 1.5V,

= -40°C to +85°C, unless otherwise noted.) (Note 5)

SKP/SDN NO FAULT Input Level 12 15 V

SKP/SDN, 4-Level Logic Input Current

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

SKP/SDN, TON, S0, S1 = GND or V

-3 3 µA

PWM CONTROLLER

Input Voltage Range

DC Output Voltage Accuracy (Notes 2, 3)

VPCS Input Bias Current I

VPCS Transconductance G

FB Input Resistance R

ILIM Input Leakage Current I

On-Time (Note 4) t

Minimum Off-Time (Note 4) t

BIAS AND REFERENCE

Quiescent Supply Current (VCC)I

Quiescent Supply Current (VDD)I

Quiescent Supply Current (V+) I+ Measured at V+ 40 µA

Shutdown Supply Current (VCC) SKP/SDN = GND 5 µA

Shutdown Supply Current (VDD) SKP/SDN = GND 5 µA

PARAMETER SYMBOL CONDITIONS MIN MAX UNITS

Battery voltage, V+ 2 28

VPS

ILIM

OFF(M IN)

, V

V+ = 4.5V to 28V, VPCS = GND, DAC codes from 0.925V to 2.0V

V+ = 4.5V to 28V, VPCS = GND, DAC codes from 0.700V to 0.900V

V+ = 4.5V to 28V, VPCS = GND, DAC codes from 0.600V to 0.675V

= 0 or 28V -1 +1 µA

VPCS

= 0 to -40mV 18 22

VPS

= 0 to -100mV 16.5 22

VPS

380kHz nominal, R

150kHz nominal, R

38kHz nominal, R

= 0 or 5.0V 100 nA

ILIM

V+ = 5.0V, VFB = 1.2V TON = GND 250 290

V+ = 12V, VFB = 1.2V

TON = REF, open, or V

TON = GND 375

Measured at VCC, FB forced above the regulation point

Measured at VDD, FB forced above the regulation point

= 47kΩ -12 +12

TIME

= 120kΩ -8 +8TIME Frequency Accuracy

TIME

= 470kΩ -12 +12

TIME

TON = REF 165 215

TON = open 320 390

TON = V

4.5 5.5

-1 +1

-1.5 +1.5

-1.83 +1.83

115 265 kΩ

465 563

500

2.5 mA

5 µA

µS

MAX1813

Dynamically-Adjustable, Synchronous Step-Down Controller with Integrated Voltage Positioning

6 _______________________________________________________________________________________

ELECTRICAL CHARACTERISTICS (continued)

(Circuit of Figure 1, V+ = +15V, VCC= VDD= 5V, VPCS = ZMODE = GND = PGND, SKP/SDN = CODE = VCC, V

OUT

set to 1.5V,

= -40°C to +85°C, unless otherwise noted.) (Note 5)

)

Shutdown Supply Current (V+) SKP/SDN = GND, VCC = VDD = 0 or 5V 5 µA

Reference Voltage V

REF Fault Lockout Voltage Falling edge, 1% hysteresis 1.5 1.7 V

FAULT PROTECTION

Output Overvoltage Fault Preset Threshold

Output Undervoltage Fault Threshhold

Current-Limit Threshold (Positive, Default)

Current-Limit Threshold (Positive, Adjustable)

Negative Current-Limit Threshold

VCC Undervoltage Lockout Threshold

PGOOD Lower Trip Threshold

PGOOD Upper Trip Threshold

PGOOD Output Low Voltage I PGOOD Leakage Current High state, forced to 5.5V 1 µA

GATE DRIVERS

DH Gate Driver On-Resistance R

DL Gate Driver On-Resistance R

LOGIC AND I/O

Logic Input High Voltage V

Logic Input Low Voltage V

DAC Z-Mode Programming Resistor, Low

DAC Z-Mode Programming Resistor, High

Logic Input Current

PARAMETER SYMBOL CONDITIONS MIN MAX UNITS

REF

OVP

ITH

ON ( D H ) VBST

ON(DL

VCC = 4.5V to 5.5V, -40µA ≤ I

Measured at FB

With respect to unloaded output voltage 60 80 %

GND

ILIM = V

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

Measured at FB with respect to unloaded output voltage, falling edge

Measured at FB with respect to unloaded output voltage, rising edge

SINK

High state (pull up) 3.5

Low state (pull down) 1.0

D0−D4, CODE, SUS, ZMODE; VCC = 4.5V to 5.5V

D0−D4, CODE, SUS, ZMODE; VCC = 4.5V

to 5.5V

D0−D4, 0 to 0.4V or 2.6V to 5.5V applied to the resistor, ZMODE = CODE = GND or ZMODE = CODE = V

D0−D4, CODE = V

SUS, ZMODE = GND or V

CODE = GND 2.20 2.30

CODE = V

- V

= 1mA 0.4 V

- VLX forced to 5V 3.5 Ω

, ILIM = V

VPCS

, with respect to V

VPCS

≤ +40µA 1.98 2.02 V

REF

= 0.5V 40 60

ILIM

= 2V (REF) 143 265

ILIM

ITH

1.95 2.05

40 60 mV

-75 -35 mV

4.05 4.45 V

-15 -10.5 %

812%

2.4 V

95 kΩ

-1 +1

Ω

0.8 V

1.05 kΩ

µA

MAX1813

Dynamically-Adjustable, Synchronous Step-Down

Controller with Integrated Voltage Positioning

_______________________________________________________________________________________ 7

Note 2: Output voltage accuracy specifications apply to DAC voltages from 0.6V to 2.0V. Note 3: When the inductor is in continuous conduction, the output voltage will have a DC regulation level higher than the error-com-

parator threshold by 50% of the ripple. In discontinuous conduction (SKP/SDN = V

, light load), the output voltage will

have a DC regulation level higher than the trip level by approximately 1.5% due to slope compensation.

Note 4: On-time and off-time specifications are measured from 50% to 50% at the DH pin, with LX forced to 0, BST forced to 5V,

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

Note 5: Specifications to -40°C are guaranteed by design, not production tested.

ELECTRICAL CHARACTERISTICS (continued)

(Circuit of Figure 1, V+ = +15V, VCC= VDD= 5V, VPCS = ZMODE = GND = PGND, SKP/SDN = CODE = VCC, V

OUT

set to 1.5V,

= -40°C to +85°C, unless otherwise noted.) (Note 5)

4-Level Logic Input High (VCC) TON (200kHz operation), S0, S1

4-Level Logic Input UpperMiddle (Float)

4-Level Logic Input LowerMiddle (REF)

4-Level Logic Low (GND) TON (1000kHz operation), S0, S1 0.5 V SKP/SDN High Input Level

(Skip Mode)

SKP/SDN Float Input Level (Forced-PWM Mode)

SKP/SDN Low Input Level (Shutdown Mode)

SKP/SDN NO FAULT Input Level 12 15 V SKP/SDN, 4-Level Logic Input

Current

PARAMETER SYMBOL CONDITIONS MIN MAX UNITS

0.4

TON (300kHz operation), S0, S1 2.8 3.85 V

TON (600kHz operation), S0, S1 1.65 2.35 V

2.8 6.0 V

1.4 2.2 V

SKP/SDN, TON, S0, S1 = GND or V

-3 +3 µA

0.5 V

MAX1813

Dynamically-Adjustable, Synchronous Step-Down Controller with Integrated Voltage Positioning

8 _______________________________________________________________________________________

Typical Operating Characteristics

(Circuit from Figure 1, components from Table 2, TA= +25°C, unless otherwise noted.)

100

0.01 0.1 1 10 100

EFFICIENCY vs. LOAD CURRENT

OUT

= 1.4V)

MAX1813 toc01

LOAD CURRENT (A)

EFFICIENCY (%)

100

0.01 0.1 1 10 100

EFFICIENCY vs. LOAD CURRENT

OUT

= 1.1V)

MAX1813 toc02

LOAD CURRENT (A)

EFFICIENCY (%)

100

0.01 0.1 1 10 100

EFFECTIVE EFFICIENCY vs. LOAD CURRENT

OUT

= 1.4V)

MAX1813 toc03

LOAD CURRENT (A)

EFFECTIVE EFFICIENCY (%)

100

0.01 0.1 1 10 100

EFFECTIVE EFFICIENCY vs. LOAD CURRENT

OUT

= 1.1V)

MAX1813 toc04

LOAD CURRENT (A)

EFFECTIVE EFFICIENCY (%)

1.28

1.30

1.32

1.34

1.36

1.38

1.40

1.42

1.44

0105 15202530

OUTPUT VOLTAGE vs. LOAD CURRENT

OUT

= 1.4V)

MAX1813 toc05

LOAD CURRENT (A)

OUTPUT VOLTAGE (V)

BATT

= 24V

BATT

= 7V

PWM MODE SKIP MODE

0105 15202530

OUTPUT VOLTAGE vs. LOAD CURRENT

OUT

= 1.1V)

MAX1813 toc06

LOAD CURRENT (A)

OUTPUT VOLTAGE (V)

1.00

1.04

1.02

1.08

1.06

1.12

1.10

1.14

BATT

= 24V

BATT

= 7V

PWM MODE SKIP MODE

100

150

200

250

300

350

400

0105 15202530

SWITCHING FREQUENCY

vs. LOAD CURRENT

MAX1813 toc07

LOAD CURRENT (A)

SWITCHING FREQUENCY (kHz)

PWM MODE

SKIP MODE

OUT

= 1.4V

BATT

= 7V

275

285

295

305

315

325

084 12162024

SWITCHING FREQUENCY

vs. BATTERY INPUT VOLTAGE

MAX1813 toc08

BATTERY INPUT VOLTAGE (V)

SWITCHING FREQUENCY (kHz)

OUT

= 10A

OUT

= 1.4V

OUT

= 1.1V

EFFICIENCY CURVE LEGEND

SKIP MODE (SKIP = GND)

A1: V+ = 4.5V

B1: V+ = 7V

C1: V+ = 15V

D1: V+ = 24V

PWM MODE (SKIP = V

)

A2: V+ = 4.5V

B2: V+ = 7V

C2: V+ = 15V

D2: V+ = 24V

MAX1813

Dynamically-Adjustable, Synchronous Step-Down

Controller with Integrated Voltage Positioning

_______________________________________________________________________________________ 9

Typical Operating Characteristics (continued)

(Circuit from Figure 1, components from Table 2, TA= +25°C, unless otherwise noted.)

340

320

300

280

260

SWITCHING FREQUENCY (kHz)

240

220

2.0

1.5

1.0

0.5

DEVIATION (mV)

-0.5

VPCS

-1.0

-1.5

-2.0

SWITCHING FREQUENCY

vs. TEMPERATURE

= 20A

OUT

= 10A

OUT

= 5A

OUT

= 1A

OUT

-40 10-15 35 60 85

TEMPERATURE (°C)

CURRENT-LIMIT DEVIATION

vs. TEMPERATURE

= 2V

ILIM

= 0.5V

ILIM

-40 -15 10 35 60 85

TEMPERATURE (°C)

MAX1813 toc09

MAX1813 toc11

ON TIME

vs. TEMPERATURE

420

= 20A

OUT

= 1A

OUT

400

380

360

340

ON TIME (ns)

320

300

280

260

-40 -15 10 35 60 85

OUT

TEMPERATURE (°C)

NO-LOAD SUPPLY CURRENT

vs. BATTERY INPUT VOLTAGE (SKIP MODE)

1.2

ICC + I

BATT

1.0

0.8 V

= 1.4V

OUT

SKP/SDN = V

0.6 CODE = ZMODE = GND

0.4

SUPPLY CURRENT (mA)

0.2

08124 162024

BATTERY INPUT VOLTAGE (V)

MAX1813 toc10

= 5A

= 10A

MAX1813 toc12

NO-LOAD SUPPLY CURRENT

vs. BATTERY INPUT VOLTAGE (PWM MODE)

ICC + I

BATT

SUPPLY CURRENT (mA)

= 1.4V

OUT

SKP/SDN = FLOAT

CODE = ZMODE = GND

084 12162024

BATTERY INPUT VOLTAGE (V)

MAX1813 toc13

TRANSITION FREQUENCY vs. R

1000

(kHz)

100

SLEW

TA = -40°C, 25°C, 85°C

10 100 1000

(kΩ)

TIME

MAX1813 toc14

MAX1813

Dynamically-Adjustable, Synchronous Step-Down Controller with Integrated Voltage Positioning

10 ______________________________________________________________________________________

Typical Operating Characteristics (continued)

(Circuit from Figure 1, components from Table 2, TA= +25°C, unless otherwise noted.)

20µs/div

LOAD TRANSIENT

(PWM MODE)

20A

MAX1813 toc15

1.41V

1.31V

10A

1.36V

A. I

OUT

= 0.3A TO 22A, 10A/div

B. V

OUT

= 1.4V, 50mV/div

SKP/SDN = FLOAT

µs/div

LOAD TRANSIENT

(SKIP MODE)

20A

MAX1813 toc16

1.41V

1.31V

10A

1.36V

A. I

OUT

= 0.3A TO 22A, 10A/div

B. V

OUT

= 1.4V, 50mV/div

SKP/SDN = V

20µs/div

LOAD TRANSIENT

(VOLTAGE POSITIONING DISABLED)

20A

MAX1813 toc17

1.46V

1.36V

10A

1.41V

A. I

OUT

= 0.3A to 22A, 10A/div

B. V

OUT

= 1.4V, 50mV/div

SKP/SDN = FLOAT

40A

20A

1.4V

100mV

-100mV

A. I B. V C. VPCS, 200mV/div ILIM = V

OUTPUT OVERLOAD WAVEFORM

= 0 TO 40A, (0 to 35mΩ), 20A/div

OUT

= 1.4V, 1V/div

OUT

40µs/div

MAX1813 toc18

DYNAMIC TRANSITION

(ZMODE TRANSITION)

10A

-10A

1.3V

1.2V

1.1V

A. V

= 0 TO 5V, 5V/div

ZMODE

B. PGOOD, 5V/div C. INDUCTOR CURRENT, 10A/div

= 1.3V TO 1.15V, I

D. V

OUT

CODE = V

µs/div

OUT

MAX1813 toc19

= 1A, 100mV/div

15A

-5A

-15A

1.3V

0.85V

DYNAMIC TRANSITION

(SUS TRANSITION)

A. V

= 0 TO 5V, 5V/div

SUS

B. PGOOD, 5V/div C. INDUCTOR CURRENT, 10A/div

= 1.3V TO 0.85V, I

D. V

OUT

CODE = V

µs/div

= 1A, 500mV/div

OUT

MAX1813 toc20

MAX1813

Dynamically-Adjustable, Synchronous Step-Down

Controller with Integrated Voltage Positioning

______________________________________________________________________________________ 11

Typical Operating Characteristics (continued)

(Circuit from Figure 1, components from Table 2, TA= +25°C, unless otherwise noted.)

1.6V

1.4V

20A

STARTUP WAVEFORM

(HEAVY LOAD)

MAX1813 toc21

1.6V

1.4V

10A

STARTUP WAVEFORM

(NO LOAD, PWM MODE)

MAX1813 toc22

= 0 TO 1.6V, 2V/div

A. V

SKP/SDN

B. PGOOD, 5V/div

= 1.4V, R

C. V

OUT

D. INDUCTOR CURRENT, 20A/div

STARTUP WAVEFORM

(NO LOAD, SKIP MODE)

1.4V

10A

= 0 TO 5V

A. V

SKP/SDN

B. PGOOD, 5V/div

= 1.4V, NO LOAD, 1V/div

C. V

OUT

D. INDUCTOR CURRENT, 10A/div

200µs/div

= 63mΩ, 1V/div

OUT

200

µs/div

MAX1813 toc23

200

µs/div

= 0 TO 1.6V, 2V/div

A. V

SKP/SDN

B. PGOOD, 5V/div

= 1.4V, NO LOAD, 1V/div

C. V

OUT

D. INDUCTOR CURRENT, 10A/div

SHUTDOWN WAVEFORM

1.6V

1.4V

20A

= 0 TO 1.6V, 2V/div

A. V

SKP/SDN

B. PGOOD, 5V/div

= 1.4V, R

C. V

OUT

D. INDUCTOR CURRENT, 20A/div

µs/div

= 63mΩ, 1V/div

OUT

MAX1813 toc24

MAX1813

Dynamically-Adjustable, Synchronous Step-Down Controller with Integrated Voltage Positioning

12 ______________________________________________________________________________________

Pin Description

PIN NAME FUNCTION

1V+

2 VPCS

3 SKP/SDN

4 TIME

5 FB Feed b ack Inp ut. C onnect FB to the j uncti on of the exter nal i nd uctor and outp ut cap aci tor ( Fi g ur e 1) .

6CC

7, 8 S0, S1

10 TON

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

Current-Sense Input. Connect a current-sense resistor (R voltage on VPCS controls both the voltage-positioning and current-limit circuits. The slope of the voltage-positioned output is controlled with the current-sense resistor and the gain resistor connected between CC and REF. See Setting Voltage Positioning. The current-limit threshold is set by ILIM. If the current-sense signal (inductor current × R will not initiate a new cycle. VPCS can also be connected to LX to reduce component count, but CC must be connected to REF to disable the voltage positioning.

Combined Shutdown and Skip-Mode Control. Drive SKP/SDN to GND for shutdown, leave SKP/SDN open for low-noise forced-PWM mode, or drive to V

Shutdown mode: SKP/SDN = GND Low-noise forced-PWM mode: SKP/SDN = open Normal pulse-skipping operation: SKP/SDN = V

Low-noise forced PWM mode causes inductor current recirculation at light loads and suppresses pulse-skipping operation. Forcing SKP/SDN with 12V to 15V clears the fault latch and disables undervoltage protection, overvoltage protection, and thermal shutdown with otherwise normal pulseskipping operation. Exiting shutdown clears the fault latch.

Do not connect SKP/SDN to voltages over 15V.

Slew-Rate Adjustment Pin. Connect a resistor from TIME to GND to set the internal slew-rate clock. A 470kΩ to 47kΩ resistor sets the clock from 38kHz to 380kHz, respectively:

= 150kHz x 120kΩ / R

SLEW

Compensation Capacitor and Voltage-Positioning Gain Adjustment. Connect a 47pF to 1000pF (47pF typ) capacitor from CC to GND to adjust the loop’s response time. Connect a resistor (R CC to REF to set the gain of the voltage positioning amplifier.

OUT OUT PROG

where the voltage-positioning amplifer’s transconductance (G

Suspend-Mode Voltage Select Inputs. S0 and S1 are 4-level logic inputs that select the suspendmode VID code for for the suspend-mode multiplexer inputs. If SUS is high, the suspend-mode VID code is delivered to the DAC. See Suspend-Mode Internal Mux.

Analog Supply Voltage Input for PWM Core. Connect VCC to the system supply voltage (4.5V to 5.5V) through a series 20Ω resistor. Bypass to GND with a 0.22µF or greater capacitor as close to the MAX1813 as possible.

On-Time Selection-Control Input. This is a 4-level input used to determine DH on-time. Connect to GND, REF, or V 1000kHz, REF = 600kHz, floating = 300kHz, and V

, or leave TON unconnected to set the following switching frequencies: GND =

TIME

()

) exceeds the current-limit threshold, the MAX1813

SENSE

for normal pulse-skipping operation:





GR V

m AVPS VPCS











= 200kHz.

) between VPCS and PGND. The

SENSE









REF







) is typically 20µS.

AVPS

) from

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