April 1997

PRELIMINARY

ML4901

High Current Synchronous Buck Controller

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GENERAL DESCRIPTION

The ML4901 high current synchronous buck controller has

been designed to provide high efficiency DC/DC

conversion for next generation processors such as the

The ML4901 controller, when combined with 2 external

MOSFETs, generates output voltages between 2.1V and

3.5V from a 12V supply. The output voltage is selected via

an internal 4-bit DAC. Output currents in excess of 14A

can be attained at efficiencies greater than 90%.

The ML4901 can be enabled/disabled via the SHDN pin.

While disabled, the output of the regulator is completely

isolated from the circuit’s input supply. The ML4901

employs fixed-frequency PWM control combined with a

dual mode control loop to provide excellent load transient

response.

FEATURES

s

requirements

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DC regulation to +1% maximum

s

Proprietary circuitry provides transient response of +5%

maximum over 300mA to 14A load range

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Programmable output voltage (2.1V to 3.5V) is set by an

onboard 4-bit DAC

s

Synchronous buck topology for maximum power

conversion efficiency

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Fixed frequency operation for easier system integration

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Integrated antishoot-through logic, short circuit

protection, and UV lockout

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Shutdown control provides load isolation

3.5V

REFERENCE

7

VREF

GND

P DRV

N DRV

ISENSE

PWR GOOD

15

UVLO

13

10

14

VDD

+

–

16

PROTECT

+

–

VDAC

1

D0

2

D1

3

D2

4

D3

4 BIT DAC

4.4V

10.4V

8

5

SHDN

+

–

+

–

VFB

VDAC + 3%

VDAC - 3%

VFB

9

PWR GND

12

CONTROL

LOGIC

+

–

-95mV

+

–

VDAC

+

–

COMP

11

200kHz

35µA

+

–

+

–

VFB

VDAC - 3%

VDAC - 10%

VDAC + 3%

VDAC + 10%

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