Hi team,
How about the output current of each channel when working at 5V and 6-ch are all at normal work?
In the POWER RATINGS part of the datasheet, it seems the maximum current is about 242mW/5.5V=44mA, but in the ABSOLUTE MAXIMUM RATINGS part of the datasheet, it seems the maximum output current is 15mA that not aligned with 15mA*6=90mA.
Hi Lucas,
Let me explain both power dissipation and max output current separately below.
Max power dissipation:
Power dissipation is calculated by the current consumed by device and these are ICC1 and ICC2. For example for ISO7760, ICC1 for worst-case conditions of datarate DR= 100Mbps and VCC1 = 5.5V is 9mA and this corresponds to max power dissipation PD1 = 5.5.V * 9mA = ~50mW. Similarly, ICC2 for VCC2 = 5.5V and datarate = 100Mbps is 44mA and hence power max power dissipation PD2 = 5.5V * 44mA = ~242mW. Hence the total power dissipation PD = 292mW.
Please note that the output current sourced out of output channels is not dissipated in device and hence it doesn't contribute much to power dissipation in device. For example, when the output voltage is 5V and the max recommended output current is 4mA, the max voltage drop at in device is going to be 0.4V (please refer to VOH spec in datasheet). Hence power dissipation due to max output current is 0.4V * 4mA = 1.6mW only for each channel.
Max output current:
Please note that device operation is only guaranteed under recommended operating conditions stated in datasheet. Any operation of device outside of recommended operating conditions but still under absolute max ratings doesn't guarantee device operation but the device will be able to withstand those conditions and not get damaged. This is also stated in the footnote under absolute max rating, I am copying below for your reference.
Hence, for all customer operating conditions the max output current (source/sink) per channel to be considered as ±4mA and not beyond that. Since the device is going to be primarily interfaced to other digital devices (like MCUs), 4mA per channel is much more than sufficient for those devices. For example, the input channels of ISO7760 itself consume only about 10µA max and this current comes from the output channel of the device interfaced (like MCU).
Let me know if you have any questions, thanks.
Regards,
Koteshwar Rao
