ADuM1200 drive MMBF170L mosfet

Question

Hi, 
 My original designing use 5V optocoupler to finish the isolation function, optocoupler output drive the MMBF170L mosfet at ON or OFF state with very low frequency. 
 Now, I feeling ADuM1200 chip also can finish the same function, the better thing is this way need less current than optocoupler. 
 Due to I never use ADuM1200 chip to drive the MOSFET, I have a little bit worry about whether it can work well. 
 Could you helps to take a look it, whether it is a normal usage without risk. 
 Thanks.

ADIApproved · Accepted Answer

You might also consider the ADuM1240/45 since the switching frequency is low. These micropower isolators have longer prop delay and a more restricted power supply range, but static power dissipation can be as low as a few &micro;A. The ADuM1240 has a default high output state when the input supply is disabled, while the ADuM1245 is default low.)

ADIApproved · Answer

Hi Weidong: 
 The schematic is OK. Only one suggestion to place R84 directly between G, S of Q8. 
 As Dave has suggested, please pay attention to the fai-safe logic status when choosing digital isolator. it appears during the period of VDD1 and VDD2 to ramp up. 
 please go to below link to search for the right part: 
 https://www.analog.com/en/parametricsearch/11037 
 Chris

ADIApproved · Answer

Hi Weidong: 
 material is only one factor of price, there are also others such as market size, volume...... 
 besides ADuM1200, ADuM724x and ADuM120/1N could also be considered. 
 there is schmitt trigger circuit designed in side the input port, so there is no transition rate limit. 
 Regards 
 Chris

ADIApproved · Answer

Also Weidong, the ADuM1100/1200 are older generation products. The latest generation is ADuM110N (1-ch) and ADuM120N (2-ch). They are more cost-effective and have better performance and robustness.

ADIApproved · Answer

Hi Weidong: 
 When VDD2 is below UVLO point, the output is high impedance. By adding 10kohm pull down resistor, we can get a logic L output. 
 
 Chris

ADIApproved · Answer

Hi, 
 how fast do you want to turn on/off Q6? 
 
 ADuM1200's output impedance is around 60-70 ohm. 
 if 10K ohm is exactly value for R113 in your application, ADuM1200 can turn on Q6 well. 
 Chris

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ADuM1200 drive MMBF170L mosfet