SMP402

1-Watt Buck Regulator IC

20-72 VDC Input

Non-isolated DC Output

®

Product Highlights

Integrated Power Switch and CMOS Controller

• Output power > 1 W from 48 VDC input

• Adjustable output voltage

• Integrated solution minimizes overall size

High-voltage, Low-capacitance MOSFET Output

• Designed for ISDN T1 telecommunications applications

• Low capacitance allows for high frequency operation

High-voltage Buck Regulator

• Internal pre-regulator self-powers the IC on start-up

• Designed for low power consumption

• Minimum external parts required

Built-In Self-protection Circuits

• Undervoltage lockout

• Thermal shutdown

• Input polarity/level sense

Description

The

SMP402,

intended

for

non-isolated

ISDN

telecommunications power supply applications, combines a

high voltage power MOSFET switch with a switchmode power

system controller in a monolithic integrated circuit.

Few

external components are required to implement a low cost

power supply which meets stringent ISDN specifications. High

frequency operation reduces total power supply size.

The P-channel power MOSFET switch features include high

voltage, low R

results in a reduction in gate drive power, and also facilitates

higher frequency operation.

The controller section of the SMP402 contains all the blocks

required to drive and control the power stage: start-up pre-

regulator circuit, oscillator, bandgap reference, error amplifier,

gate driver and level shift.

Protection features include

undervoltage lockout, thermal shutdown, and input polarity

and level sensing.

The SMP402 is available in a 16-pin plastic SOIC package.

Figure 1. Typical Application.

ORDERING INFORMATION

PART

PACKAGE

T

j

NUMBER

OUTLINE

RANGE

SMP402SC

S16A

0 to 120

°C

PI-555A-123091

48 VDC

5 VDC

+

-

+

-

SMP402

Figure 2. Pin Configuration.

OUT

PI-553B-012892

POLARITY

VS

EA IN

EA OUT

VBIAS

CEXT

VIN

VLS

ENABLE

D GND

SENSE -

REXT

16

15

14

13

12

11

10

9

1

2

3

4

5

6

7

8

LEVEL

A GND

SENSE+

January 1996