NB650/NB650H

– 6A, 28V, FAST-TRANSIENT, SYNCHRONOUS STEP-DOWN CONVERTERS

NB650/NB650H Rev. 1.13

www.MonolithicPower.com

4

10/7/2019

MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.

Preliminary Specifications Subject to Change

© 2019 MPS. All Rights Reserved.

PIN FUNCTIONS

QFN17

Pin #

Name

Description

1,2

SW

Switch Output. Connect using wide PCB traces.

3

BST

Bootstrap. Requires a capacitor between SW and BST to form a floating supply across

the high-side switch driver.

4

PG

Power Good. Output is an open drain and is high if the output voltage exceeds 90% of

the nominal voltage. The

re is a delay from FB≥90%×Vref to PG goes high.

5

EN

EN=1 to enable. For automatic start-up, connect to VIN with a

100kΩ resistor.

6,7

VID1

VID2

VID inputs. Control signals for the output-voltage scaling. Acts as the control signals for

the internal VID switches. Usually uses an external resistor in parallel with the low-side

FB resistor. Changing the VID ON/OFF state changes the FB divider scaling and result

in different output voltages.

8

VCC

Internal LDO output. The power supply of the internal control circuits. Decouple with 1

μF

capacitor.

9,10

GND

System Ground. The reference ground of the regulated output voltage. Layout requires

extra care.

11

IN

Supply Voltage. Operates from a 4.5V-to-28V input rail. Requires C1 to decouple the

input rail. Connect using wide PCB traces.

12

AGND

Analog Ground.

13

FB

Feedback. Connect to the tap of an external resistor divider from the output to GND to

set the output voltage.

14,15

RFB2

RFB1

Drain of the internal VID switches. Typically uses an external resistor in parallel with the

low-side FB resistor along with the internal VID switch to change the ON/OFF state of

the VID switching to change the FB divider scaling and result in different output

voltages.

16

SS

Soft-Start. Connect an external capacitor to program the soft-start time for the switch-

mode regulator.

17

FREQ

Frequency Set during CCM. The input voltage and the frequency-set resistor between

the IN and FREQ pin determines the ON period. For best results, use an ON period

longer than 200ns.