AN2640 datasheet(11/36 Pages) STMICROELECTRONICS

11 / 36 page

AN2640

ST7LIT19BF1 - 8-bit MCU

11/36

The following are a few main features that make this microcontroller suitable for this scope:

●

Internal RC oscillator with 1% precision at 8 MHz CPU frequency

●

32 MHz timer counter clock with two independent counters for half-bridge and PFC

management

●

Analog PFC zero-current detection and half-bridge dead time generation

●

Analog comparator

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10-bit A/D Converter with 7 channels and the possibility to use an amplifier (fixed gain

8) between the input and converter

●

2 timers with 1 ms or 2 ms time base to provide timing to the system management

Figure 9.

ST7LITE1xB 20-pin SO and DIP package pinout

3.2

Use of the pins

●

Pin 1: GND

●

Pin 2: VCC. The microcontroller is supplied by means of this pin. The voltage is

generated by the L6382D5 device. To prevent noise in this pin a 100 nF capacitor must

be soldered as close as possible between this pin and GND.

●

Pin 3: reset (not used). It is advisable to connect a small capacitor to avoid undesired

reset of the micro between this pin and GND.

●

Pin 4: COMPIN+. This pin is used to protect against overcurrent on the PFC Power

MOSFET and inductor. When the current exceeds 2 A, the comparator inside the MCU

stops the ballast without using the MCU core. Figure 10 shows the detection circuit.

AN2640 Datasheet(PDF) 11 Page - STMicroelectronics