UM0900 datasheet(16/43 Pages) STMICROELECTRONICS

16 / 43 page

Board description

UM0900

16/43

Doc ID 17028 Rev 1

are available like: integrated op-amp for signal conditioning, integrated comparators for

overcurrent or short-circuit protection, and the “SMART SHUTDOWN” function. Please refer

to the STGIPL14K60 datasheets for more information.

3.3.4

Brake function

A hardware brake feature is implemented on the STEVAL-IHM025V1 demonstration board.

This feature connects the external dummy load applied to the J6 connector to the bus, to

eliminate overvoltage generated while the motor acts as a generator. Voltage on the bus is

sensed through a voltage divider net, with R32, R33 and R42 resistors, and it is compared

to the voltage reference built around the precise voltage reference U3. The brake dummy

load is switched on when voltage on the bus reaches 445 VDC and is switched off when the

voltage falls below 420 VDC. The brake function can be activated by the microcontroller

thanks to the motor-control connector (please set the W3 jumper in position “A”). The brake

threshold levels can be modified by calculating R32, R33, R42 and R45 new values.

3.3.5

Overcurrent protection

Hardware overcurrent protection (OCP) is implemented on the board. STGIPL14K60

integrates three internal comparators. Thanks to the internal connection between the

comparator output and shutdown block (see Figure 9), the intervention time of overcurrent

protection is extremely low, ranging slightly above 200 ns (Smart Shutdown).

The overcurrent protection acts as soon as the voltage on the CIN pin rises above the

internal voltage reference (typical value is 0.53 V). Considering the default value of the

shunt resistor, it follows that the maximum allowed current is equal to:

Equation 1

Note:

R3 is not connected on the STEVAL-IHM025V1.

With the default values this gives:

●

ISHUNT_MAX = 7 A

SHU NT MAX

REF

SHUNT

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