MIC2920A Datasheet, PDF (9/9 Pages) Micrel Semiconductor – 400mA Low-Dropout Voltage Regulator

MIC2920A/29201/29202/29204
capacitor. This is relatively inefficient, as increasing the
capacitor from 1µF to 220µF only decreases the noise from
430µV to 160µV_RMS for a 100kHz bandwidth at 5V output.
Noise can be reduced fourfold by a bypass capacitor across
R₁, since it reduces the high frequency gain from 4 to unity.
Pick
CBYPASS ≅
1
2 πR1 • 200 Hz
or about 0.01µF. When doing this, the output capacitor must
be increased to 10µF to maintain stability. These changes
reduce the output noise from 430µV to 100µV rms for a
100kHz 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.
Micrel
Automotive Applications
The MIC2920A 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 (100µA 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.
Typical Applications
V _IN
+VIN
VOUT
GND
*VOUT ≈5V
V_OUT = 5V
+
10µF
+VIN
100kΩ
8
VIN
VOUT
ERROR
OUTPUT
5 _ERROR
VOUT ^{1 1.2 26V}
3
SHUTDOWN
INPUT
3
SHUTDOWN
OFF
GND ADJUST
ON
4
7
1.23V
R1 100
pF
10µ⁸F^{70 25}
VOUT = VREF x (1 +
R1
R2
)
VREF
R2
Figure 2. MIC2920A-5.0 Fixed +5V Regulator
NOTE: PINS 2 AND 6 ARE LEFT OPEN
Figure 3. MIC29202/29204 Adjustable Regulator. Pinout is for
MIC29204.
+VIN
8
ERROR
OUTPUT
+VIN
5 _{ERROR VOUT} ^{1 *VOUT ≈VIN}
MIC2951
SHUTDOWN
INPUT
3
SD
OFF
GND
ON
4
AD_FJ_BUST
7
*MINIMUM INPUT-OUTPUT VOLTAGE RANGES FROM 40mV TO 400mV,
DEPENDING ON LOAD CURRENT.
≥ 5.3V
8
+VIN
SHUTDOWN
INPUT
3
SHUT-
HIGH = OFF _DOWN
VOUT ¹
LOW = ON
GND ADJUST
4
7
100pF
VCC OUT
+
300kΩ ^10µF
1%
HIGH = 5V OUT
LOW = 3.3V OUT
470 kΩ
220kΩ 180kΩ
1%
1%
2N2222
PIN 3 LOW= ENABLE OUTPUT. Q1 ON = 3.3V, Q1 OFF = 5.0V.
Figure 4. MIC29204 Wide Input Voltage Range Current Limiter Figure 5. MIC29202/29204 5.0V or 3.3V Selectable Regulator
with Shutdown. Pinout is for MIC29204.
January 1998
3-17