MC34270
MC34271
Liquid Crystal Display and
Backlight Integrated Controller
The MC34270 and MC34271 are low power dual switching voltage
regulators, 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 . 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, these devices are ideally suited
for battery powered computer, consumer, and industrial equipment where an
extension of useful battery life is desirable.
LIQUID CRYSTAL DISPLAY
AND BACKLIGHT
INTEGRATED CONTROLLER
SEMICONDUCTOR
TECHNICAL DATA
t
32
1
MC34270 and MC34271 Features:
FB SUFFIX
PLASTIC PACKAGE
CASE 873
Uncommitted Switching Regulators Allow Both Positive and Negative
Supply Voltages
Logic Enable Allows Microprocessor Control of All Outputs
Synchronizable to External Clock
Mode Commandable for ELD and LCD Interface
Frequency Synchronizable
PIN CONNECTIONS
32
30
29
28
27
26
25
Gnd
VA
Vref
EN1
EN2
MOSFET is a trademark of Motorola, Inc.
31
RT
Auxiliary Output Bias Voltages Enable Load Control via N–Channel FETs
Sync
•
•
•
•
•
Low Standby Bias Current of 5.0 µA
SW1
•
•
1 DS1
2 Ref1
Rating
Symbol
Value
Unit
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FB2 22
4 Comp1
VDD
16
Vdc
PD
1.43
W
RθJA
RθJC
100
60
°C/W
°C/W
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
Device
Tstg
– 55 to +150
°C
MC34270FB
Comp2 21
Output #1 and #2 Switch Current
Storage Temperature Range
MOTOROLA ANALOG IC DEVICE DATA
9
8 Drv1
V0
D2 18
V1
7 D1
V2
S2 19
V3
6 S1
V4
SS2 20
VDD
5 SS1
Mode
Power Dissipation and
Thermal Characteristics
Maximum Power Dissipation
Case 873
Thermal Resistance, Junction–to–Ambient
Thermal Resistance, Junction–to–Case
ELD
Input Voltage
Ref2 23
3 FB1
MAXIMUM RATINGS (TA = 25°C, unless otherwise noted.)
DS2 24
10
11
12
13
14
15
16
VB 17
ORDERING INFORMATION
MC34271FB
Operating
Temperature Range
TA = 0° to +70°C
Package
QFP–32
QFP–32
3–641
