BQ4050: Zener and TVS diodes

Mikhail Ipatev

Part Number: BQ4050

Hello.
Please tell me, is it possible to use zener diodes to protect the gates MOSFETs as shown in the figure (red circles)?

I have doubts that when the VT5 transistor is closed, at a battery voltage of, for example, 16.8V, a current of approximately 3mA will flow through the VDZ20 -> R20 circuit,

which will increase the self-discharge of the battery. Moreover, when the transistor VT7 is closed, with a large voltage surge from the side of the charger, too much current

may flow through the VDZ21-> R27 circuit, which will damage the microcircuit.

In addition, is it possible to use a bidirectional TVS diode VDZ10 (blue circle) at the battery output, or should I use a unidirectional one?

over 2 years ago

0 Wyatt Keller over 2 years ago

TI__Guru** 105740 points

Hello Mikhail,

Yes you can use Zener diodes to help protect the gates.

I'm not sure I understand your questions completely, there should be very little self discharge if the Zener voltages are selected correctly.

As long as the voltages at each pin is within the datasheet spec the gauge will not be damaged, if you are seeing large transients then that could cause damage.

As long as the TVS diode as the appropriate voltage rating then either bidirectional or unidirectional is fine.

Sincerely,

Wyatt Keller

0 Mikhail Ipatev over 2 years ago in reply to Wyatt Keller

Prodigy 60 points

Thanks for the answer. I have already found a solution: you can install zener diodes, 
only there is an error on my circuit - the VDZ3 zener diode needs to be deployed, 
since the VT6 transistor is a P-channel.

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BQ4050: Zener and TVS diodes