
LM320L/LM79LXXAC/LM13121 Series
3-Terminal Negative Regulators
General Description
The LM320L/LM79LXXAC/LM13121 dual marked series of
3-terminal negative voltage regulators features fixed output
voltages of −5V, −12V, and −15V with output current capa-
bilities in excess of 100mA. These devices were designed
using the latest computer techniques for optimizing the pack-
aged IC thermal/electrical performance. The LM79LXXAC
series, even when combined with a minimum output com-
pensation capacitor of 0.1µF, exhibits an excellent transient
response, a maximum line regulation of 0.07% V
O
/V, and a
maximum load regulation of 0.01% V
O
/mA.
The LM320L/LM79LXXAC/LM13121 series also includes, as
self-protection circuitry: safe operating area circuitry for out-
put transistor power dissipation limiting, a temperature inde-
pendent short circuit current limit for peak output current
limiting, and a thermal shutdown circuit to prevent excessive
junction temperature. Although designed primarily as fixed
voltage regulators, these devices may be combined with
simple external circuitry for boosted and/or adjustable volt-
ages and currents. The LM79LXXAC series is available in
the 3-lead TO-92 package, 8-lead SOIC package, and the
6-Bump micro SMD package. The LM320L series is avail-
able in the 3-lead TO-92 package.
For output voltage other than −5V, −12V and −15V, the
LM137L series provides an output voltage range from 1.2V
to 47V.
Features
nPreset output voltage error is less than ±5% overload,
line and temperature
nSpecified at an output current of 100mA
nEasily compensated with a small 0.1µF output
capacitor
nInternal short-circuit, thermal and safe operating area
protection
nEasily adjustable to higher output voltages
nMaximum line regulation less than 0.07% V
OUT
/V
nMaximum load regulation less than 0.01% V
OUT
/mA
nSee AN-1112 for micro SMD considerations
Typical Applications
Fixed Output Regulator
00774801
*Required if the regulator is located far from the power supply filter. A 1µF
aluminum electrolytic may be substituted.
**Required for stability. A 1µF aluminum electrolytic may be substituted.
Adjustable Output Regulator
00774803
−V0= −5V − (5V/R1 + IQ)•R2,
5V/R1 >3I
Q
Connection Diagrams
6-Bump micro SMD
00774820
Bump Side Down
TO-92 Plastic Package (Z)
00774802
Bottom View
January 2003
LM320L/LM79LXXAC/LM13121 Series 3-Terminal Negative Regulators
© 2003 National Semiconductor Corporation DS007748 www.national.com