Datasheet

LM317M
C
ADJ
R
2
Input Output
Adjust
Vref=1.25V
V
O
D2
1N4002
R
1
240 Ω
I
ADJ
C
0.1
I
μF
V
I
D1
1N4002
C
1.0 F
I
μ
LM317M
www.ti.com SLVS297P –APRIL 2000–REVISED MARCH 2014
8 Applications and Implementation
8.1 Application Information
The LM317M is a linear voltage regulator. The feedback is the output terminal to adjust terminal differential. The
output voltage can be set to any value from 1.25-V to Vout maximum with two resistors.
8.2 Typical Application
8.2.1 Design Requirements
For this design example, use the parameters listed in Table 1.
Table 1. Design Parameters
DESIGN PARAMETER EXAMPLE VALUE
Input voltage range (Output Voltage + 2.5V) to 37V
Output voltage Vref × (1 + R2/R1) + I
adj
× R2
8.2.2 Detailed Design Procedure
8.2.2.1 Input Capacitor
An input capacitor is not required, but it is recommended, particularly if the regulator is not in close proximity to
the power-supply filter capacitors. A 0.1-µF ceramic or 1-µF tantalum provides sufficient bypassing for most
applications, especially when adjustment and output capacitors are used.
8.2.2.2 Output Capacitor
An output capacitor improves transient response, but it not needed for stability.
8.2.2.3 Feedback Resistors
The feedback resistor set the output voltage using Equation 2.
Vref × (1 + R2/R1) + I
adj
× R2 (2)
8.2.2.4 Adjustment Terminal Capacitor
The optional adjustment terminal capacitor will improve ripple rejection by preventing the amplification of the
ripple. When capacitor is used and VOUT > 6V, a protection diode from adjust to output is recommended.
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