MIC29150 Micrel Semiconductor, MIC29150 Datasheet - Page 15

• Manufacturer Part Number: MIC29150
• Description: High-Current Low-Dropout Regulators
• Manufacturer: Micrel Semiconductor

Adjustable Regulator Design
The adjustable regulator versions, MIC29xx2 and MIC29xx3,
allow programming the output voltage anywhere between
1.25V and the 26V maximum operating rating of the family.
March 2000
MIC29150/29300/29500/29750
Device
MIC29150 .................................................... 5mA
MIC29300 .................................................... 7mA
MIC29500 .................................................. 10mA
MIC29750 .................................................. 10mA
Figure 4. Adjustable Regulator with Resistors
V IN
10µF
V OUT = 1.235V
MIC29152BT
R1
R2
[1 + (R1 / R2)]
22µF
Minimum Load
V OUT
15
Two resistors are used. Resistors can be quite large, up to
1M , because of the very high input impedance and low bias
current of the sense comparator: The resistor values are
calculated by:
Where V
component definition. Applications with widely varying load
currents may scale the resistors to draw the minimum load
current required for proper operation (see above).
Error Flag
MIC29xx1 and MIC29xx3 versions feature an Error Flag,
which looks at the output voltage and signals an error
condition when this voltage drops 5% below its expected
value. The error flag is an open-collector output that pulls low
under fault conditions. It may sink 10mA. Low output voltage
signifies a number of possible problems, including an over-
current fault (the device is in current limit) and low input
voltage. The flag output is inoperative during overtempera-
ture shutdown conditions.
Enable Input
MIC29xx1 and MIC29xx2 versions feature an enable (EN)
input that allows ON/OFF control of the device. Special
design allows “zero” current drain when the device is dis-
abled—only microamperes of leakage current flows. The EN
input has TTL/CMOS compatible thresholds for simple inter-
facing with logic, or may be directly tied to 30V. Enabling the
regulator requires approximately 20 A of current.
O
is the desired output voltage. Figure 4 shows
R
1
MIC29150/29300/29500/29750
R
2
1.240
V
OUT
1
Micrel