PWM output of TM173OFM22S connection to fan

[tlindenblatt]

Hi,

I want to control the PWM Input of a Papst 4154 N/2 H8P.

According to the manual the PWM-Input is open collector and expects a frequency of 2...10 kHz.

The fan has 4 wires:

24VDC

GND

PWM

Tacho

I've configured analog output 4 of my TM173OFM22S to provide a PWM frequency of 2kHz and variable duty cyle (set via the display).

Can I directly connect AO4 to the PWM input and Signal GND to GND or do I need to consider anything else? I could not find any further documentation about the open collector outputs.

The fan is powered by the same 24VDC/20A PSU as the TM173OFM22S.

Many thanks

Tobi

[M_Cervati]

Dear Tobi,

open collector PWM needs a pull-up resistor connected to 24VDC.

TM173O hasn't this resistor on board so verify if load to drive has this pull-up internally, otherwise you have to add externally, taking in account the maximum sink current is 50mA (like specified in hardware user guide).

 

Best regards

Marco Cervati

[tlindenblatt]

Dear Marco,

Thanks for the reply.

In the meantime I got a wiring diagram from the manufacturer:

The fan supply +UB is 24VDC

The internal reference is 5V and R1 is 10kOhm.

I'm a bit unsure because of this 5V internal reference. Can I connect AO4 to the PWM-Input, connect the grounds and everything works?

[FedericoM · Accepted solution]

Hello,

you can connect AO4 configured as PWM to input and connect together the GND of Fan and TM173O.