MIC29710 View Datasheet(PDF) - Micrel

Part Name

Description

Manufacturer

MIC29710

7.5A Fast-Response LDO Regulator

Micrel 

Micrel, Inc.

Adjustable Regulator Design

The adjustable regulator version, MIC29712, allows pro-

gramming the output voltage anywhere between 1.25V

and the 16V maximum operating rating of the family.

Two resistors 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:

R1 =

R2 ×

⎜⎜⎝⎛

VOUT

1.240

− 1⎟⎟⎠⎞

Where VO is the desired output voltage. Figure 4 shows

component definition.

MIC29712BT

VIN

4.75 to 5.25

10µF

R1

100k

R2

56.2k

VOUT

3.45V

33µF

VOUT = 1.240V× [1 + (R1 / R2)]

Figure 4. Adjustable Regulator with Resistors

MIC29710/29712

Enable Input

The MIC29712 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-amperes of leakage current flows. The EN

input has TTL/CMOS compatible thresholds for simple

interfacing with logic, or may be directly tied to VIN.

Enabling the regulator requires approximately 20µA of

current into the EN pin.

Minimum Load Current

The MIC29710/12 regulators are specified between finite

loads. If the output current is to small, leakage currents

dominate and the output voltage rises. A 10mA minimum

load current is necessary for proper regulation.

Voltage

2.85

2.9

3.0

3.1

3.15

3.3

3.45

3.525

3.6

3.8

4.0

4.1

Standard (Ω)

R1

R2

100k

76.8k

100k

75.0k

100k

69.8k

100k

66.5k

100k

64.9k

100k

60.4k

100k

56.2k

93.1k

51.1k

100k

52.3k

100k

48.7k

100k

45.3k

100k

43.2k

Figure 5. MIC29712 Resistor Table

October 2006

9

M9999-101906

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