© Semiconductor Components Industries, LLC, 2000

April, 2000 – Rev. 0

1

Publication Order Number:

MC34271/D

MC34271

Liquid Crystal Display and

Backlight Integrated

Controller

The MC34271 is a low power dual switching voltage regulator,

specifically designed for handheld and laptop applications, to provide

several regulated output voltages using a minimum of external parts.

Two uncommitted switching regulators feature a very low standby

bias current of 5.0

µA, and an operating current of 7.0 mA capable of

supplying output currents in excess of 200 mA.

Both devices have three additional features. The first is an ELD

Output that can be used to drive a backlight or a liquid crystal display.

The ELD output frequency is the clock divided by 256. The second

feature allows four additional output bias voltages, in specific

proportions to VB, one of the switching regulated output voltages. It

allows use of mixed logic circuitry and provides a voltage bias for

N–Channel load control MOSFETs

t. The third feature is an Enable

input that allows a logic level signal to turn–“off” or turn–“on” both

switching regulators.

Due to the low bias current specifications, this device is ideally

suited for battery powered computer, consumer, and industrial

equipment where an extension of useful battery life is desirable.

MC34271 Features:

Negative Supply Voltages

FETs

Rating

Symbol

Value

Unit

Input Voltage

VDD

16

Vdc

Power Dissipation and

Thermal Characteristics

Maximum Power Dissipation – Case 873

PD

1.43

W

Thermal Resistance, Junction–to–Ambient

R

θJA

100

°C/W

Thermal Resistance, Junction–to–Case

R

θJC

60

°C/W

Output #1 and #2 Switch Current

ISL & ISB

500

mA

Output #1 and #2 “Off”–State Voltage

VSL

60

Vdc

Feedback Enable MOSFETs

“Off”–State Voltage

VLF

20

Vdc

Operating Junction Temperature

TJ

125

°C

Operating Ambient Temperature

TA

0 to +70

°C

Storage Temperature Range

Tstg

– 55 to +150

°C

Device

Package

Shipping

ORDERING INFORMATION

MC34271FB

QFP–32

250 Units / Tray

QFP–32

FB SUFFIX

CASE 873

http://onsemi.com

PIN CONNECTIONS AND

MARKING DIAGRAM

(Top View)

1

32

32

DS1

Ref1

FB1

Comp1

SS1

S1

D1

Drv1

DS2

Ref2

FB2

Comp2

SS2

S2

D2

VB

31

30

29

27

28

26

25

124

23

22

21

20

19

18

17

2

3

4

5

6

7

8

910

11

12

14

13

15

16

A

= Assembly Location

WL = Wafer Lot

YY = Year

WW = Work Week