5.13

Overcurrent response time

The TSC20x is composed of a current sensing and a comparator, which are two essential IPs to detect the

occurrence of an overcurrent, and alerting its presence. Thanks to a typical slew rate of 7 V/µs for the current

sensing and 300 ns as propagation delay for the comparator, the TSC200 is a perfect device for fast overcurrent

protection application.

The overcurrent protection circuit, shown in Figure 46, uses the TSC200 to control an external P-channel

MOSFET which opens the current path under overload conditions. The latched output of the TSC200’s

comparator prevents the circuit from oscillating, and the push-button resets the current path after an overcurrent

condition.

In the typical application described in Figure 46, a current in the range of 2 A to 20 A is monitored through a shunt

of 10 mΩ. The TSC200 is powered with a VCC = 5 V.

The full-scale output voltage should theoretically be in the range of 400 mV to 4 V.

The output voltage range 4 V to 5 V is reserved for OCP detection. So, the divider bridge on the comparator input

is selected as follows:

R1 = 178 Ω

R2 = 1 kΩ

Figure 46. Typical OCP application

+

-

OUT

VIN+

Vcc

12V

VIN-

Reference

voltage 0.6V

CMPOUT

RESET

-

+

CMPIN

GND

12V

Vcc

5V

R1=1kΩ

R2=178Ω

Rp=5.1kΩ

Rr=470kΩ

Cr=0.22µF

Cd=100nF

In the most critical case where low current (2 A) is flowing into the load, the output of the TSC200 is close to 400

mV, so the current sensing output would need 0.7 µs to pass from 400 mV to 5 V after the overcurrent event.

The comparator, due to its good propagation delay, requires only 300 ns to change its state from low to high level.

So, after an overcurrent, the system takes, in a worst condition scenario (small current into the load), less than 1

µs to switch-off the PMOS, as described by Figure 47.

TSC200, TSC201, TSC202

Overcurrent response time

DS13882 - Rev 2

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