Semiconductor Components Industries, LLC, 2000
April, 2000 – Rev. 0
1
Publication Order Number:
MC34271/D
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
μ
A, 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, this device is ideally
suited for battery powered computer, consumer, and industrial
equipment where an extension of useful battery life is desirable.
MC34271 Features:
Low Standby Bias Current of 5.0
μ
A
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
Auxiliary Output Bias Voltages Enable Load Control via N–Channel
FETs
MAXIMUM RATINGS
(TA = 25
°
C, unless otherwise noted.)
Rating
Symbol
Value
Unit
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Thermal Resistance, Junction–to–Ambient
Thermal Resistance, Junction–to–Case
PD
R
θ
JA
R
θ
JC
ISL & ISB
VSL
VLF
1.43
100
60
W
°
C/W
°
C/W
Power Dissipation and
Thermal Characteristics
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Output #1 and #2 Switch Current
500
mA
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Output #1 and #2 “Off”–State Voltage
60
Vdc
Feedback Enable MOSFETs
20
Vdc
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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
E
DS2
32
1
DS1
Ref1
FB1
Comp1
SS1
S1
D1
Drv1
Ref2
FB2
Comp2
SS2
S2
D2
VB
S
S
T
G
A
V
E
9
M
10
D
11
3
13
V
12
V
14
V
15
V
16
E
31
30
29
27
28
26
25
1
24
23
22
21
20
19
18
17
2
3
4
5
6
7
8
M
A
A
WL = Wafer Lot
YY
= Year
WW = Work Week
= Assembly Location