LM8322 datasheet(7/42 Pages) NSC

7 / 42 page

8.0 Application Example

30013601

FIGURE 1. Typical Application

8.1 FEATURES

The application example shown in Figure 1 supports the fol-

lowing features:

•

8 x 9 standard keys.

•

8 special function keys (SF keys) with wake-up capability

by forcing a WAKE_INx pin to ground. Pressing a SF key

overrides any other key in the same row.

•

ACCESS.bus (I2C-compatible) interface for

communication with the host.

•

Hardware IRQ interrupt to host to signal keypad, error, and

status events. By default, this is an open-drain output, so

an external pullup resistor may be required to avoid false

assertion. The host can program this output for push-pull

mode, in which case the pullup might not be required, if

the host can ignore a false assertion before the LM8322

has been programmed.

•

Two LEDs driven by PWM outputs with programmable

ramp-up and ramp-down. PWM_2 (shared with GPIO_15

and CONFIG_2) could be used as an additional PWM

driver port to control a third external LED.

•

ACCESS.bus address is selected by the CONFIG_1 and

CONFIG_2 inputs. These pins may also be used as GPIO

pins after reset initialization has occurred. If extra GPIO

pins are not needed, CONFIG_1 and CONFIG_2 may be

tied directly to V

CC and GND.

•

Crystal pins XTAL_IN and XTAL_OUT may be used to

connect to an external 32.768 kHz crystal or receive an

external 32.768 kHz clock input for running the PWM

peripheral. By default, the PWM is clocked by an on-chip

clock source.

LM8322 데이터시트(PDF) 7 Page - National Semiconductor (TI)