MIC29510 Datasheet, PDF (8/8 Pages) Micrel Semiconductor – 5A Fast-Response LDO Regulator Preliminary Information

MIC29510/29512
Adjustable Regulator Design
MIC29512BT
Micrel
the 16V maximum operating rating of the family. Two resis-
tors are used. Resistors can be quite large, up to 100kΩ,
because of the very high input impedance and low bias
current of the sense comparator. The resistor values are
calculated by:
V_OUT
R1 = R2 × ( –—— – 1 )
1.240
VIN
4.75 to 5.25
10µF
R1
100k
R2
56.2k
VOUT
3.45V
47µF
Where V_O is the desired output voltage. Figure 4 shows
component definition.
Enable Input
The MIC29512 versions features an enable (EN) input that
allows ON/OFF control of the device. Special design allows
“zero” current drain when the device is disabled—only micro-
VOUT = 1.240V × [1 + (R1 / R2)]
amperes of leakage current flows. The EN input has TTL/
CMOS compatible thresholds for simple interfacing with
Figure 4. Adjustable Regulator with Resistors
The adjustable regulator version, MIC29512, allows pro-
logic, or may be directly tied to V_IN. Enabling the regulator
requires approximately 20µA of current into the EN pin.
gramming the output voltage anywhere between 1.25V and
3
Resistor Value Table for the MIC29512 Adjustable Regulator
Voltage
2.85
2.9
3.0
3.1
3.15
3.3
3.45
3.6
3.8
4.0
4.1
Standard (Ω)
R1
R2
100k
100k
100k
100k
100k
100k
100k
100k
100k
100k
100k
76.8k
75.0k
69.8k
66.5k
64.9k
60.4k
56.2k
52.3k
48.7k
45.3k
43.2k
1997
3-103