MIC2937A Micrel Semiconductor, MIC2937A Datasheet - Page 9

• Manufacturer Part Number: MIC2937A
• Description: 750mA Low-Dropout Voltage Regulator
• Manufacturer: Micrel Semiconductor

MIC2937A/29371/29372
regulators with a bypass capacitor across R
the high frequency gain from 4 to unity. Pick
or about 0.01 F. When doing this, the output capacitor must
be increased to 10 F to maintain stability. These changes
reduce the output noise from 430 V to 100 V
kHz bandwidth at 5V output. With the bypass capacitor
added, noise no longer scales with output voltage so that
improvements are more dramatic at higher output voltages.
Typical Applications
*MINIMUM INPUT-OUTPUT VOLTAGE RANGES FROM 40
Figure 4. MIC29372 Wide Input Voltage Range Current Limiter
MIC2937A/29371/29372
DEPENDING ON LOAD CURRENT.
Figure 2. MIC2937A-5.0 Fixed +5V Regulator
C
GND
BYPASS
+V IN
GND
+V IN
V IN
V
IN
ADJUST
V
OUT
V
OUT
2 R
1
+
• 200 Hz
1
*V
V OUT
10µF
OUT
1
m
, since it reduces
5V
V IN
V TO 400
V
RMS
OUT
for a 100
m
V,
= 5V
26
Automotive Applications
The MIC2937A is ideally suited for automotive applications
for a variety of reasons. It will operate over a wide range of
input voltages with very low dropout voltages (40mV at light
loads), and very low quiescent currents (100 A typical).
These features are necessary for use in battery powered
systems, such as automobiles. It is a “bulletproof” device with
the ability to survive both reverse battery (negative transients
up to 20V below ground), and load dump (positive transients
up to 60V) conditions. A wide operating temperature range
with low temperature coefficients is yet another reason to use
these versatile regulators in automotive designs.
SHUTDOWN PIN LOW= ENABLE OUTPUT. Q1 ON = 3.3V, Q1 OFF = 5.0V.
Figure 5. MIC29372 5.0V or 3.3V Selectable Regulator with
Shutdown.
ON
SHUTDOWN
INPUT
3.3V
ON
V OUT = V REF x (1 +
SHUTDOWN
INPUT
Input
0
1
OFF
Figure 3. MIC29372 Adjustable Regulator
Output
5V
3.3V
5.0V
SHUTDOWN
OFF
GND
+5V to +7V
SHUTDOWN
+V IN
470 k
GND ADJUST
ADJUST
R
R
1
V
2
OUT
V
)
IN
V
REF
V
OUT
100pF
220k
1%
1.23V
2N2222
300k
180k
R .01
1%
1%
R
V
1
1.2V
OUT
2
October 1999
µF
+
V CC OUT
10µF
10µF
26V
Micrel