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LM79MXX
3-Terminal 0.5A Negative Voltage Regulator
Features
•
•
•
•
•
•
No External Components Required
Output Current in Excess of 0.5A
Internal Thermal Overload
Internal Short Circuit Current Limiting
Output Transistor Safe Area Compensation
Output Voltages of -5V, -6V, -8V, -12V, -15V , -18V and -
24V
Description
The LM79MXX series of 3-Terminal medium current
negative voltage regulators are monolithic integrated circuits
designed as fixed voltage regulators. These regulators
employ internal current limiting, thermal shutdown and safe
area compensation making them essentially indestructible.
TO-220
1
1. GND 2. Input 3. Output
Schematic Diagram
GND
R2
Q8
D1
D2
D3
Q12
R1
R3
Q10
Q9
R4
Q11
R5
R8
Q14
Q16
R13
R7
D5
Q18
Q2
Q3
Q17
Q24 Q25
Q5
Q1
Q4
Q6
Q7
Q19
R24
R25
Q20
R19
R18
C1
C2
R17
D4
Q23
Q26
R20
Q21 Q22
R21
R22
Q27
R23
R16
R6
Q13
R9
Q15
R12
R14
R10 R11
R15
OUT
IN
Rev. 1.0.3
©2009 Fairchild Semiconductor Corporation
LM79MXX
Absolute Maximum Ratings
Parameter
Input Voltage(for V
O
= -5V to -18V)
(for V
O
= -24V)
Thermal Resistance Junction-Cases
Thermal Resistance Junction-Air
Operating Temperature Range
Storage Temperature Range
Symbol
V
I
V
I
R
θJC
R
θJA
T
OPR
T
STG
Value
-35
-40
5
65
0 ~ +125
-65 ~ +150
Unit
V
V
°C/W
°C/W
°C
°C
Electrical Characteristics (LM79M05)
(Refer to test circuit, 0°C
≤T
J
≤
+125°C, l
O
=350mA, V
I
= -10V,unless otherwise specified, C
I
=0.33μF,C
O
=0.1μF)
Parameter
Output Voltage
Symbol
V
O
Conditions
T
J
= +25°C
I
O
= 5mA to 350mA
V
I
= -7V to -25V
T
J
=+25°C
V
I
= -7V to -25V
V
I
= -8V to -25V
Min.
-4.8
-4.75
-
-
-
-
-
-
-
-
54
-
-
-
Typ.
-5
-5
7.0
2.0
30
3.0
-
-
-0.2
40
60
1.1
140
650
Max.
-5.2
-5.25
50
30
100
6.0
0.4
0.4
-
-
-
-
-
-
mA
mV/°C
μV
dB
V
mA
mA
V
Unit
Line Regulation (Note1)
Load Regulation (Note1)
Quiescent Current
Quiescent Current Change
Output Voltage Drift
Output Noise Voltage
Ripple Rejection
Dropout Voltage
Short Circuit Current
Peak Current
ΔV
O
ΔV
O
I
Q
ΔI
Q
ΔVo/ΔT
V
N
RR
V
D
I
SC
I
PK
mV
mV
mA
I
O
= 5mA to 500mA
T
J
= +25°C
T
J
= +25°C
I
O
= 5mA to 350mA
I
O
= 200mA
V
I
= -8V to -25V
I
O
= 5mA
f = 10Hz, 100kHz
T
A
= +25°C
f = 120Hz
V
J
= -8 to -18V
T
J
=+25°C, I
O
= 500mA
T
J
= +25°C, V
I
= -35V
T
J
= +25°C
Note:
1. Load and line regulation are specified at constant junction temperature. Change in V
O
due to heating effects must be taken
into account separately. Pulse testing with low duty is used.
2
LM79MXX
Typical Applications
V
I
2
LM79MXX
1
3
V
O
2.0uF
1.0uF
Figure 1. Fixed Output Regulator
V
I
LM79MXX
V
O
R
1
C
1
_
2.2uF
SOLID
+
TANTALUM
_
1uF
_
+
C
2
25uF
R
2
+
C
3
SOLID
TANTALUM
Figure 2. Variable Output
Notes:
1. Required for stability. For value given, capacitor must be solid tantalum. 25μF aluminum electrolytic may be substituted.
2. C
2
improves transient response and ripple rejection. Do not increase beyond 50μF.
3
LM79MXX
Mechanical Dimensions
Package
Dimensions in millimeters
TO-220 [ SINGLE GAUGE ]
4
LM79MXX
Ordering Information
Product Number
LM79M05CT
Package
TO-220
Operating Temperature
0 ~ +125°C
DISCLAIMER
FAIRCHILD SEMICONDUCTOR RESERVES THE RIGHT TO MAKE CHANGES WITHOUT FURTHER NOTICE TO ANY
PRODUCTS HEREIN TO IMPROVE RELIABILITY, FUNCTION OR DESIGN. FAIRCHILD DOES NOT ASSUME ANY
LIABILITY ARISING OUT OF THE APPLICATION OR USE OF ANY PRODUCT OR CIRCUIT DESCRIBED HEREIN; NEITHER
DOES IT CONVEY ANY LICENSE UNDER ITS PATENT RIGHTS, NOR THE RIGHTS OF OTHERS.
LIFE SUPPORT POLICY
FAIRCHILD’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES
OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF FAIRCHILD SEMICONDUCTOR
CORPORATION. As used herein:
1. Life support devices or systems are devices or systems
which, (a) are intended for surgical implant into the body,
or (b) support or sustain life, and (c) whose failure to
perform when properly used in accordance with
instructions for use provided in the labeling, can be
reasonably expected to result in a significant injury of the
user.
www.fairchildsemi.com
7/6/09 0.0m 001
Stock#DS903555
©
2009 Fairchild Semiconductor Corporation
2. A critical component in any component of a life support
device or system whose failure to perform can be
reasonably expected to cause the failure of the life support
device or system, or to affect its safety or effectiveness.
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