SA555: Discharge sink current specification for SA555 timer

Nilesh Khupase

Part Number: SA555

Hello,

What is the maximum allowed discharge sink current specification for SA555 timer, i was just wondering whether we need to add any current limiting resistor in the capacitor discharge path?

Thanking you in advance.

3 months ago

0 Ron Michallick 3 months ago

TI__Guru**** 174286 points

Hello Nilesh,

A resistor is not required. A resistor can be added to limit the peak current to a desired value. The resistor is optional.

0 Nilesh Khupase 3 months ago

Intellectual 510 points

Hello Ron,

Thank you for the reply. Does it mean that SA555 timer IC Discharge pin can sink any amount of peak current without any adverse effect?

0 Ron Michallick 3 months ago in reply to Nilesh Khupase

TI__Guru**** 174286 points

Nilesh,

The charge stored in a capacitor is not likely to damage the internal discharge transistor. The energy is low. Even if the peak current caused a secondary breakdown, it would not last long.

The discharge transistor can only sink a finite amount of current. The transistor will set an unspecified current limit.

0 Nilesh Khupase 3 months ago in reply to Ron Michallick

Intellectual 510 points

Thank you!!

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SA555: Discharge sink current specification for SA555 timer