ELEKTOR FORUMS

Hi there;
Can anybody help please?
The problem is that it is impossible to start up instruments/sensors with a higher amp rating than 1Amp. How could I overcome this problem if I need a higher start up current. lets say 3 Amp. Is it possible to change any components within the circuit to achieve the higher pwr demand?
I attached a drawing for the individual channel circuit.
Your help is much appreciated!
Karsten

A description of the circuit:

The Current Limit Circuit Breaker Board provides independent overcurrent protection channels
between a DC power supply (i.e. MAP55-1024) and several loads. Each load can be current limited up to 1A.

A single +24Vdc power supply provides input power to this board. This power is then distributed to 8
independent short-circuit protected output channels.
A simple Zener diode voltage regulator generates +5Vdc from the incoming 24Vdc. This +5Vdc powers
the quad AND gates U3 and U4, the fault indicator red LEDs D4 to D11, and provides a reference for the
enable inputs of the LT1161 MOSFET drivers U1 and U2. The green LED D12 indicates that +5Vdc is
present.
A 2-input AND gate is used to monitor the fault status of every channel on the LT1161 driver by
monitoring the enable input and voltage output of that channel. When either or both of these signals is
low, the logic output is low turning on the red LED for that particular channel. It is a fault when the enable
input to the LT1161 driver is below 1.4Vdc or the output current exceeds ISET value, or a short circuit is
detected. There are eight red LEDs (D4-D11) for fault indication.
The circuit will try to restart itself automatically when a fault is detected. The restart time is determined by
the CTimer (C1-C8) capacitors.
The trip output current (ISET) can be manipulated by means of a sense resistor (Rsense). The selection of
Rsense is based on Rsense = 50mV / ISET. (i.e., to set a trip current of 1A, Rsense is 0.05ohm). ISET can have a
maximum value of 1A. When the value of ISET is exceeded or a short-circuit is detected, the output for
that particular channel is turned off until the fault is removed.
In the –002 version of the board instead of the red LEDs, the fault signals are connected to the connector
J4 that can be connected to a digital input channel. The digital input channel normally has a logic high
when no fault is detected. When a fault is detected, the logic output of the AND gate is low and current
sinking. This is intended for remote monitoring of a fault condition.

Cheers Sarma
I attached the schematics in pdf. format, for a single channel. Thanks for your help so far Sarma.
What do I have to change in order to adjust the Rsense?
Kind regards
Karsten

[ admin ]
content removed. Unable to remove post in its entirety.