# What is a (side) current alarm?

On the technical sheet of a motor controller integrating two BTS7960B (picture below), the description of the 8 PINs on the board is as follows:

RPWM: Forward level or PWM signal input, active HIGH

LPWM: Reverse level or PWM signal input, active HIGH

R_EN: Forward drive enable input, HIGH enable, LOW Close

L_EN: Reverse drive enable input, HIGH enable, LOW Close

R_IS: Forward drive - side current alarm output

L_IS: Reverse drive - side current alarm output

VCC: 5V power input

GND: Ground

I tried to search for "side current alarm" and "side current" but all I found was about "high/low-side current sensing". Being a newbie in electronics, I'm not sure what is the connection between all those terms.

What is a "side current alarm"? How is it used?

• Can you add a datasheet link for the board into your question? – Transistor Aug 25 '18 at 20:15

I think that the text is badly typed. If we change

R_IS: Forward drive - side current alarm output
L_IS: Reverse drive - side current alarm output


to

R_IS: Forward drive-side current alarm output
L_IS: Reverse drive-side current alarm output


it implies that the alarm is on the "drive-side" of the board as opposed to the control side.

The BTS7960 datasheet says:

The status pin IS is used as a combined current sense and error flag output. In normal operation (current sense mode), a current source is connected to the status pin, which delivers a current proportional to the forward load current flowing through the active high side switch. If the high side switch is inactive or the current is flowing in the reverse direction no current will be driven except for a marginal leakage current IIS(LK). The external resistor RIS determines the voltage per output current. E.g. with the nominal value of 8500 for the current sense ratio kILIS = IL / IIS, a resistor value of RIS = 1kΩ leads to VIS = (IL / 8.5 A)V. In case of a fault condition the status output is connected to a current source which is independent of the load current and provides IIS(lim). The maximum voltage at the IS pin is determined by the choice of the external resistor and the supply voltage. In case of current limitation the IIS(lim) is activated for 2 * tCLS.

• I think it is much simpler than that. "forward" and "drive" should not be read separately: "Forward drive - side" means "on a 'forward drive' circuit side" – Maple Aug 25 '18 at 20:30