MAX797H 查看數據表（PDF） - Maxim Integrated

零件编号

产品描述 (功能)

生产厂家

MAX797H

High-Voltage / Step-Down Controller with Synchronous Rectifier for CPU Power

Maxim Integrated 

High-Voltage, Step-Down Controller with

Synchronous Rectifier for CPU Power

______________________________________________________________Pin Description

PIN NAME

FUNCTION

1

SS

Soft-Start Timing Capacitor Connection. Ramp time to full current limit is approximately 1ms/nF.

Disables pulse-skipping mode when high. Connect SKIP to GND for normal use. Do not leave unconnected.

2

SKIP

With SKIP grounded, the device automatically changes from pulse-skipping operation to full PWM operation

when the load current exceeds approximately 30% of maximum.

3

REF

Reference Voltage Output. Bypass REF to GND with 0.33µF minimum.

4

GND

Low-noise Analog Ground and Feedback Reference Point

Oscillator Synchronization and Frequency Select. Tie SYNC to GND or VL for 150kHz operation; tie to REF for

5

SYNC

300kHz operation. A high-to-low transition begins a new cycle. Drive SYNC with 0V to 5V logic levels (see

Electrical Characteristics for VIH and VIL specifications). SYNC capture range is guaranteed to be 190kHz to

340kHz.

6

SHDN

Shutdown Control Input, Active Low. Logic threshold is set at approximately 1V (VTH of an internal N-channel

MOSFET). Tie SHDN to V+ for automatic start-up.

Feedback Input. Regulates at FB = REF (approximately 2.505V) in adjustable mode. FB is a Dual ModeTM

input that also selects the fixed-output voltage settings as follows:

• Connect to GND for 3.3V operation.

7

FB

• Connect to VL for 5V operation.

• Connect to a resistor divider for adjustable mode. FB can be driven with 5V Rail-to-Rail® logic to change

the output voltage under system control.

8

CSH

Current-Sense Input, High Side. Current-limit level is 100mV referred to CSL.

9

CSL

Current-Sense Input, Low Side. CSL also serves as the feedback input in fixed-output modes.

10

V+

Battery Voltage Input (4.5V to 30V). Bypass V+ to PGND close to the IC with a 0.1µF capacitor. Connects to a

linear regulator that powers VL.

5V Internal Linear-Regulator Output. VL is also the supply-voltage rail for the chip. It is switched to the output

11

VL

voltage via CSL (VCSL > 4.5V) for automatic bootstrapping. Bypass to GND with 4.7µF. VL can supply up to

5mA for external loads.

12 PGND Power Ground

13

DL

Low-Side Gate-Drive Output. DL normally drives the synchronous-rectifier MOSFET. Swings 0V to VL.

14

BST

Boost Capacitor Connection for High-Side Gate Drive (0.1µF)

15

LX

Switching Node (inductor) Connection. LX can swing 2V below ground without hazard.

16

DH

High-Side Gate-Drive Output. DH normally drives the main buck switch. It is a floating driver output that

swings from LX to BST, riding on the LX switching-node voltage.

Dual Mode is a trademark of Maxim Integrated Products.

Rail-to-Rail is a registered trademark of Nippon Motorola Ltd.

_______________________________________________________________________________________ 5

Share Link: