FP131 datasheet(8/11 Pages) FEELING

8 / 11 page

FP131

This datasheet contains new product information. Feeling Technology reserves the rights to modify the product specification without notice.

No liability is assumed as a result of the use of this product. No rights under any patent accompany the sales of the product.

Website: http://www.feeling-tech.com.tw

Rev. 1.0

8/11

Function Description

Current Shunt Regulator

The figure below shows the FP131 current shunt block. Load current (IS) flows from power supply

and a dropout voltage (VIN

+-VIN-) appears across the sense resistor (RS).

Assume the internal NPN transistor’s collector current is same as the emitter current (IO) and VIP

is very close to VIN, the FP131 transfer function will be:

----- (1)

In this figure, the (VIN

+-VIN-), is equal to IS x RS and the current shunt output voltage (VCSO) is

equal to IO x RL. The final transfer function for rail current measurement in this application is:

CSO





----- (2)



----- (3)

LOAD

RG1

RG2

VIN

VIP

VCC

GND

CSO

VIN+VIN-

Note

1. The minimum operating voltages of VCC, VIP and VIN are 2.7V. If these supply voltages are

lower than 2.7V, the transfer function at current shunt output (CSO) of FP131 is no longer

correct.

2. Do not force a VIN voltage 15V higher than VIP. This condition would generate a leakage

current and an incorrect voltage at FP131’s output.

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FP131 Datasheet(PDF) 8 Page - Feeling Technology Corp.