ST72589BW datasheet(19/158 Pages) STMICROELECTRONICS

Part #	ST72589BW

Description	8-BIT MCU WITH NESTED INTERRUPTS, DOT MATRIX LCD, ADC, TIMERS, PWM-BRM, SPI, SCI, I²C, CAN INTERFACES

PDF	158 Pages

Scroll/Zoom	100%

Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

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19 / 158 page

ST72589BW, ST72389BW

19/158

3.2 LOW CONSUMPTION OSCILLATOR

The oscillator of the ST72589 and ST72389 devic-

es is a Crystal/Ceramic Resonator Oscillator. Its

architecture is based on a constant current to min-

imize the consumption. It can be used either with

an external resonator or an external source.

This oscillator allows a high accuracy to supply the

clock for the ST7 CPU and its internal peripherals.

Using a Crystal/Ceramic Resonator

The resonator and the load capacitances have to

be connected as shown in Figure 10 and have to

be mounted as close as possible to the oscillator

pins in order to minimize output distortion and

start-up stabilization time.

Figure 10. Main Crystal/Ceramic Resonator

Using an External Clock Source

In this mode, a square clock signal with ~50% duty

cycle has to drive the OSC1 pin while the OSC2

pin is tied to ground (see Figure 11).

Figure 11. Main External Clock Source

OSC1

OSC2

LOAD

CAPACITANCES

ST7

CL2

CL1

OSC1

OSC2

EXTERNAL

ST7

SOURCE

ST72589BW Datasheet(PDF) 19 Page - STMicroelectronics