LM340-N, LM78xx
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SNOSBT0J – FEBRUARY 2000 – REVISED DECEMBER 2013
LM340-N/LM78XX Series 3-Terminal Positive Regulators
Check for Samples: LM340-N, LM78xx
FEATURES
DESCRIPTION
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The LM140/LM340A/LM340-N/LM78XXC monolithic
3-terminal positive voltage regulators employ internal
current-limiting, thermal shutdown and safe-area
compensation, making them essentially indestructible.
If adequate heat sinking is provided, they can deliver
over 1.0A output current. They are intended as fixed
voltage regulators in a wide range of applications
including local (on-card) regulation for elimination of
noise and distribution problems associated with
single-point regulation. In addition to use as fixed
voltage regulators, these devices can be used with
external components to obtain adjustable output
voltages and currents.
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Complete Specifications at 1A Load
Output Voltage Tolerances of ±2% at Tj = 25°C
and ±4% Over the Temperature Range
(LM340A)
Line Regulation of 0.01% of VOUT/V of ΔVIN at
1A Load (LM340A)
Load Regulation of 0.3% of VOUT/A (LM340A)
Internal Thermal Overload Protection
Internal Short-circuit Current Limit
Output Transistor Safe Area Protection
P+ Product Enhancement Tested
Considerable effort was expended to make the entire
series of regulators easy to use and minimize the
number of external components. It is not necessary to
bypass the output, although this does improve
transient response. Input bypassing is needed only if
the regulator is located far from the filter capacitor of
the power supply.
The 5V, 12V, and 15V regulator options are available
in the steel TO-3 power package. The
LM340A/LM340-N/LM78XXC series is available in the
TO-220 plastic power package, and the LM340-N-5.0
is available in the SOT-223 package, as well as the
LM340-5.0 and LM340-12 in the surface-mount
DDPAK/TO-263 package.
Typical Applications
*Required if the regulator is located far from the power supply filter.
**Although no output capacitor is needed for stability, it does help
transient response. (If needed, use 0.1 μF, ceramic disc).
Figure 1. Fixed Output Regulator
VOUT = 5V + (5V/R1 + IQ) R2 5V/R1 > 3 IQ,
load regulation (Lr) ≈ [(R1 + R2)/R1] (Lr of LM340-5).
Figure 2. Adjustable Output Regulator
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