LM2931ACD2T ON Semiconductor, LM2931ACD2T Datasheet - Page 8

• Manufacturer Part Number: LM2931ACD2T
• Description: LOW DROPOUT VOLTAGE REGULATORS
• Manufacturer: ON Semiconductor

6.4 V to 30 V
8
The LM2931 series can be current boosted with a PNP transistor. The
D45VH7, on a heatsink, will provide an output current of 5.0 A with an input
to output voltage differential of approximately 1.0 V. Resistor R in
conjunction with the V BE of the PNP determines when the pass transistor
begins conducting. This circuit is not short circuit proof.
Input
Input
6.0 V
V in
Figure 21. Constant Intensity Lamp Flasher
C in
0.1
100
68
Figure 19. (5.0 A) Low Differential
Figure 17. Fixed Output Regulator
R
+
D45VH7
+
Input
Voltage Regulator
100
LM2931C
LM2931–5.0
I B
33 k
Output
Fixed
LM2931–5.0
Gnd
2.0 k
8.2 k
Output
6.2 V
0
100
100
f osc = 2.2 Hz
+
+
C O
#345
5.0 V @ 5.0 A
CM
Output
LM2931 Series
V out
Input
V in
The circuit of Figure 19 can be modified to provide supply protection against
short circuits by adding the current sense resistor R SC and an additional PNP
transistor. The current sensing PNP must be capable of handling the short
circuit current of the LM2931. Safe operating area of both transistors must be
considered under worst case conditions.
0.01
100
1.0
0.1
C in
0.1
V out
10
R
10
V in = 5.6 V
V out = 5.0 V
I O = 100 mA
V n rms 10 Hz to 10 MHz
|Z O | @ 40 kHz
T A = 25 C
+
Figure 20. Current Boost Regulator with
Figure 18. Adjustable Output Regulator
51 k
Switch Position 1 = Output “On”, 2 = Output “Off”
V
Figure 22. Output Noise Voltage versus
|Z O |, MAGNITUDE OF CAPACITOR IMPEDANCE (m )
2
ref
1
1
Output Capacitor Impedance
Short Circuit Projection
Output
MOTOROLA ANALOG IC DEVICE DATA
Inhibit
)
R SC
Input
R 2
R 1
100
)
I B
Adjustable
LM2931C
Output
I
Adj
+
Gnd
R 2
100
Output
Adjust
LM2931–5.0
22.5 k
1.0 k
I Adj
w
Unstable
Marginally
Stable
Stable
R 1
R 2
R 1
R 1 R 2
)
100
R 2
C O
+
Output
10 k
V out