MAX232: data rate when C1 = C2 = 0.085uF

Noriyuki Takahashi

Part Number: MAX232

Hi team,

Could you tell the data rate when C1 = C2 = 0.085uF?

They need 12kbps at max but C1 and C2 are 0.085uF. So they are not sure this is OK, because C1 and C2 are 1uF at the condition of the datasheet. Could you give any suggestion for this?

Regards,

Noriyuki Takahashi

over 2 years ago

0 Eric Hackett over 2 years ago

TI__Guru 60042 points

Takahashi-san,

An engineer has been notified of this thread and will respond by tomorrow. Thank you for your patience.

Regards,

Eric Hackett

0 Hao L over 2 years ago

TI__Mastermind 25705 points

Takahashi-san,

I think MAX232 works with 0.085uF C1/C2 (same ratio and similar value). Please check out this blog for the detail of charge pump operation.

How the RS-232 transceiver’s regulated charge-pump circuitry works - Analog - Technical articles - TI E2E support forums

0 Noriyuki Takahashi over 2 years ago in reply to Hao L

TI__Genius 9245 points

Hao,

So do you mean that C1/C2 will not affect the data rate?

Then, do you know any concerns or things they need to take care when they use MAX232 with 0.085uF C1/C2?

Regards,

Noriyuki Takahashi

0 Clemens Ladisch over 2 years ago in reply to Noriyuki Takahashi

Guru 243120 points

Smaller capacitors increase the ripple frequency, reduce the ripple voltage, and increases the output resistance (which reduces the output voltage, depending on the load).

Interface

Interface forum

MAX232: data rate when C1 = C2 = 0.085uF