Minimal System; Schematic; Serial Interface; Power Supply - Cypress FR81S CY91F52 Series Recommendation For Hardware Setup

2

Minimal System

This chapter gives an example for a minimum hardware system.
2.1

Schematic

The following graphic shows a schematic of a minimum hardware system. Note that for other MCU families a different
pinning is needed.
*1 only needed for dual clock devices.
*2 please refer to chapter 3.6 Recommended Power Supply Circuit.
2.2

Serial Interface

The "PC connection" section is only needed, if no 5 V external serial data lines for programming exist. The MAX232 is
a standard level shifter, which converts the 5 V levels of the MCU to ±12V RS232V24 levels and vice versa.
If you use a 3.3 V system a MAX3232 is recommended.
Please consider, that the internal charge pumps of the level shifter can produce noise on the +5 Volts line, which can
influence the ADC, if AVCCn and AVRHn are directly (unfiltered) connected to it.
2.3

Power supply

The power supply should be from 2.7 Volts to 5.5 Volts for normal usage. If a different supply voltage is used please
refer to the corresponding data sheet.
2.4

Analog Digital Converter Supply Pins

The analog converter supply pins (AVCCn, AVRHn / AVRLn, AVSSn) should be connected even if the ADC of the MCU
is not used. Please refer to our application note "mcu-an-300215-e-16fx_adc" for using the ADC and pin connection.
www.cypress.com
Figure 1. Principal Schematic for Minimal Requirements
Document No. 002-09375 Rev. *B
Recommendation for Hardware Setup 32-Bit FR81S Family
2