Datasheet
−10
Time − µs
−0.2
∆I
O
− Output Current Change − A
∆V
O
− Output Voltage Change − V
−5 0 5 10 15 20 25 30 35
−0.1
0
0.1
0.2
0.3
0.4
0.5
0.6
−4.0
−3.0
−2.0
−1.0
0
1.0
2.0
3.0
4.0
5.0
V
I
= 15 V
V
O
= 10 V
I
L
= 50 mA
∆I
L
= +500 mA
C
L
= 1 µF
C
ADJ
= 10 µF
C
L
= 0 µF
C
ADJ
= 0 µF
−1.0
Time − µs
−0.5 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5
1.2
1
0.8
0.6
0.4
0.2
0
−1
−0.8
−0.6
−0.4
−0.2
0
0.2
0.4
0.6
0.8
1
V
O
= 10 V
V
I
= 15 V, ∆V
I
= +1 V
I
L
= 50 mA
T
J
= 25°C
C
L
= 0 µF
C
ADJ
= 0 µF
∆V
I
− Input Voltage Change − V
∆V
O
− Output Voltage Change − V
)()1(
2
1
2
RI
R
R
VV
adjrefo
uu
LM317M
SLVS297P –APRIL 2000–REVISED MARCH 2014
www.ti.com
8.2.2.5 Protection Diodes
If the input is shorted to ground during a fault condition, protection diode (D1) prevents discharge through the
LM317M. If the output is shorted to ground during a fault condition, protection diode (D2) prevents adjust terminal
capacitor discharge through the LM317M.
8.2.2.6 Design Options and Parameters
Common Linear Regulator designs are concerned with the following parameters:
• Input voltage range
• Input Capacitor range
• Output voltage
• Output current rating
• Output capacitor range
• Input Short Protection
• Stability
• Ripple Rejection
8.2.2.7 Output Voltage
Vo is calculated as shown:
(3)
Because I
adj
typically is 50-µA, it is negligible in most applications.
8.2.2.8 Ripple Rejection
C
ADJ
is used to improve ripple rejection; it prevents amplification of the ripple as the output voltage is adjusted
higher. If C
ADJ
is used, it is best to include protection diodes.
8.2.2.9 Input Short Protection
If the input is shorted to ground during a fault condition, protection diodes provide measures to prevent the
possibility of external capacitors discharging through low-impedance paths in the IC. By providing low-impedance
discharge paths for C
O
and C
ADJ
, respectively, D1 and D2 prevent the capacitors from discharging into the output
of the regulator.
8.2.3 Application Curves
Figure 12. Line Transient Response vs Time
Figure 13. Load Transient Response vs Time
10 Submit Documentation Feedback Copyright © 2000–2014, Texas Instruments Incorporated
Product Folder Links: LM317M