Operating Information:
Over-Current Protection: The power modules have current limit protection to protect the module during output overload and short circuit conditions. During overload conditions, the power modules may protect themselves by entering a hiccup current limit mode. The modules will operate normally once the output current returns to the specified operating range. There is a typical delay of 2mS from the time an overload condition appears at the module output until the hiccup mode will occur.
Output Over-Voltage Protection: The power modules have a control circuit, independent of the primary control loop that reduces the risk of over voltage appearing at the output of the power module during a fault condition. If there is a fault in the primary regulation loop, the over voltage protection circuitry will cause the power module to shut down. The module remains off unless either the input power is recycled or the on/off switch is toggled.
The iHA Veta® family also offers a hiccup over-voltage protection once it detects that the output voltage has reached the level indicated in the Electrical Data section for the power module of interest. When the condition causing the over-voltage is corrected, the module will operate normally.
Thermal Protection: When the power modules exceed the maximum operating temperature, the modules may turn-off to safeguard the power unit against thermal damage. The module will auto restart as the unit is cooled below the over temperature threshold.
Remote On/Off: - The power modules have an internal remote on/off circuit. The user must supply an open-collector or compatible switch between the Vin(-) pin and the on/off pin. The maximum voltage generated by the power module at the on/off terminal is 15V. The maximum allowable leakage current of the switch is 50uA. The switch must be capable of maintaining a low signal Von/off < 1.2V while sinking 1mA.
It is recommended that the power module be kept off for at least 100mS each time it is turned off.
The standard on/off logic is positive logic. The power module will turn on if terminal 2 is left open and will be off if terminal 2 is connected to terminal 4. An optional negative logic is available. The power module will turn on if terminal 2 is connected to terminal 4, and it will be off if terminal 2 is left open.
An On/Off Control Circuit
Output Voltage Adjustment: The output voltage of the power module may be adjusted by using an external resistor connected between the Vout trim terminal (pin 7) and either the Sense (+) or Sense (-) terminal. If the output voltage adjustment feature is not used, pin 7 should be left open. Care should be taken to avoid injecting noise into the power module’s trim pin. A small 0.01uF capacitor between the power module’s trim pin and Sense (-) pin may help avoid this.
Vout(+)
Sense(+)
Trim
Rdown
Sense(-)
Vout(-)
Circuit to decrease output voltage
With a resistor between the trim and Sense (-) terminals, the output voltage is adjusted down. To adjust the output voltage down a
