MAX3232 Overview and usage

MAX3232 3.0V to 5.5V, Low-Power, True RS-232 Transceivers

Using Four 0.1F External Capacitors, with 0.1F decoupling cap for power supply mounted close to chip...

Current consumption is aprox 0.3mA.

Capacitor Selection

The capacitor type used for C1-C4 is not critical for proper operation; polarized or non-polarized capacitors can be used. The charge pump requires 0.1F capacitors for 3.3V operation. For other supply voltages, refer to Table below for required capacitor values. Do not use values lower than those listed in Table 2. Increasing the capacitor values (e.g., by a factor of 2) reduces ripple on the transmitter outputs and slightly reduces power consumption. C2, C3, and C4 can be increased without changing C1's value. However, do not increase C1 without also increasing the values of C2, C3, and C4, to maintain the proper ratios (C1 to the other capacitors).

When using the minimum required capacitor values, make sure the capacitor value does not degrade excessively with temperature. If in doubt, use capacitors with a higher nominal value. The capacitor's equivalent series resistance (ESR), which usually rises at low temperatures, influences the amount of ripple on V+ and V-.


Jim Jackson <jj@franjam.org.uk> Wed Mar 27 18:16:43 GMT 2013



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