4.4.1

Principle of CurrentSense signal generation

Figure 31. CurrentSense block diagram

INPUT

Vcc

OUT

To uC ADC

RPROT

RSENSE

Main MOS

Sense MOS

Fault

CS

Current sense Switch Block

Current sense

GAPG2307131200CFT

Current sense

This output is capable of providing:

•

Current mirror proportional to the load current in normal operation, delivering current proportional to

the load according to a known ratio named K

•

Diagnostics flag in fault conditions delivering fixed voltage VSENSEH

The current delivered by the current sense circuit, ISENSE, can be easily converted to a voltage VSENSE by using

an external sense resistor, RSENSE, allowing continuous load monitoring and abnormal condition detection.

Normal operation (channel ON, no fault)

While the device is operating in normal conditions (no fault intervention), VSENSE calculation can be done using

simple equations

Current provided by CurrentSense output: ISENSE = IOUT/K

Voltage on RSENSE: VSENSE = RSENSE ∙ ISENSE = RSENSE ∙ IOUT/K

Where :

•

VSENSE is the voltage measurable on RSENSE resistor

•

ISENSE is the current provided from the CS pin in current output mode

•

IOUT is the current flowing through output

•

K factor represents the ratio between PowerMOS cells and SenseMOS cells; its spread includes geometric

factor spread, current sense amplifier offset and process parameters spread of the overall circuitry

specifying the ratio between IOUT and ISENSE.

Failure flag indication

In case of power limitation/overtemperature, the fault is indicated by the CS pin which is switched to a “current

limited” voltage source, VSENSEH.

In any case, the current sourced by the CS in this condition is limited to ISENSEH.

VN7004SLH

CS - analog current sense

DS13681 - Rev 2

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