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TRS232E: calculate the power consumption of the series /resistor ROUT and Din

Frank Xiao
Genius 12055 points
Part Number: TRS232E

Hi team,

My customer wants to TRS232E in the system. We have two questions want to check with you.

1. We put 4 resistor at MCU side Rout and Din, we want to calculate the power consumption of the resistor. Do you have some ideas how to calculate it?

2. We want to check how the charge pump cap work for the Dout voltage. Do we have some detail block diagram to show the principle?

Thanks.

  • 0
    TI__Guru 62910 points

    Hi Frank,

    The power consumption through a series resistance would depend on how much current will flow through it.  Since the driver side has low output impedance (and can be approximated by an ideal voltage source), this current is primarily a function of the loading of the receiver side.  For example, the DIN ports of TRS232E have a maximum input current consumption of 200 uA.  The RIN ports have a minimum input resistance of 3 kOhms.  The DOUT ports would likely connect to a minimum load of 3 kOhms as well since this is the worst-case load condition in the RS-232 standard.  The ROUT ports would likely connect to a high-Z input, but to know the exact input current consumption you could reference the datasheet of the MCU or UART connected on that port.

    To better understand the operation of the charge pump circuitry, you could reference this blog:

    https://e2e.ti.com/blogs_/b/analogwire/archive/2018/06/28/how-the-rs-232-transceiver-s-regulated-charge-pump-circuitry-works

    Regards,
    Max