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
SMP402
+
48 VDC
-
®
+
5 VDC
-
PI-555A-123091
Figure 1. Typical Application.
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
DS(ON)
, and low capacitance. Lower capacitance
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.
VIN
VLS
ENABLE
D GND
A GND
SENSE+
SENSE -
REXT
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
OUT
POLARITY
LEVEL
VS
EA IN
EA OUT
VBIAS
CEXT
PI-553B-012892
Figure 2. Pin Configuration.
ORDERING INFORMATION
PART
NUMBER
SMP402SC
PACKAGE
OUTLINE
S16A
T
j
RANGE
0 to 120°C
January 1996
POWERINT [ POWER INTEGRATIONS, INC. ]
