I want to use this chip (ST3232CDR) as an RS232 transceiver. The problem is that I want to power the chip using 2 levels of voltage (3.3V and 5.0V) using a simple jumper, but in the datasheet (http://www.st.com/content/ccc/resource/technical/document/datasheet/group1/40/2c/7f/62/3a/3f/47/3c/CD00002253/files/CD00002253.pdf/jcr:content/translations/en.CD00002253.pdf) page 7, the recommended capacitors values are different according to supply voltage level. How can I solve this problem. Is it okay to same capacitors for the two different voltage levels? or not?
PS: I am using this chip as an RS232 transceiver to interface an ATmega32 with db9 connector using UART.
Electronic – Capacitors for MAX232
atmegadb9rs232st
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Best Answer
Just use the higher of the recommended values. For example, as per Table 9:
Typically, you'd want the lowest possible capacitance for the circuit to function - the lower, the cheaper. This is why they have a table with recommended values. However, using a higher capacitance will not hurt functionality (within reason). You might get a measurably slower start-up time, but the effect would be negligible.