MIC2920A/29201/29202/29204

Micrel, Inc.

February 2005

9

M9999-021505

SHUT-

DOWN

V

GND

4

7

8

OUT

+VIN

ADJUST

1

3

SHUTDOWN

INPUT

100pF

2N2222

1%

300kΩ

≥ 5.3V

1%

180kΩ

+

10µF

470 kΩ

HIGH = OFF

LOW = ON

LOW = 3.3V OUT

220kΩ

1%

V CC OUT

HIGH = 5V OUT

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 (100µAtypical).These

features are necessary for use in battery powered systems,

such as automobiles. It is a “bulletproof” device with the abil-

ity to survive both reverse battery (negative transients up to

20V below ground), and load dump (positive transients up to

60V) conditions.Awide operating temperature range with low

temperature coefficients is yet another reason to use these

versatile regulators in automotive designs.

tor from 1µF to 220µF only decreases the noise from 430µV

to 160µV

be reduced fourfold by a bypass capacitor across R

reduces the high frequency gain from 4 to unity. Pick

or about 0.01µF. When doing this, the output capacitor must

be increased to 10µF to maintain stability. These changes re-

duce 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 improve-

ments are more dramatic at higher output voltages.

NOTE: PINS 2 AND 6 ARE LEFT OPEN

IN

OUT

GND ADJUST

E R R O R

5

3

4

1

8

SHUTDOWN

V

V

E R R O R

OUTPUT

SHUTDOWN

INPUT

IN

+V

100kΩ

OUT

V

1.2

26V

1

R

100

pF

10µF

2

R

1.23V

R E F

V

7

V OUT = VR E F x (1 +

)

1

R

2

R

O FF

ON

IN

OUT

GND

V

+V

IN

V

OUT

V

= 5V

10µF

+

Figure 2. MIC2920A-5.0 Fixed +5V Regulator

Figure 3. MIC29202/29204 Adjustable Regulator. Pinout is for

MIC29204.

Typical Applications

Figure 5. MIC29202/29204 5.0V or 3.3V Selectable Regulator

with Shutdown. Pinout is for MIC29204.

Figure 4. MIC29204 Wide Input Voltage Range Current Limiter

PIN 3 LOW= ENABLE OUTPUT. Q1 ON = 3.3V, Q1 OFF = 5.0V.

1

2 πR1 • 200 Hz

=

IN

OUT

GND ADJUST

E R R O R

5

3

4

1

8

SD

V

+V

E R R O R

OUTPUT

SHUTDOWN

INPUT

IN

+V

OUT

*V

7

O F F

ON

IN

= V

* Minimum Input-Output Voltage ranges from 40mV to 400mV, depending on load current