ISL24202

9

FN7587.0

March 15, 2011

when not being driven. CE should be pulled low before powering

the device down to ensure that any glitches or transients during

power-down will not cause unwanted EEPROM overwriting.

The CE pin has a Schmitt trigger on the input to prevent false

triggering during slow transitions of the CE pin. The CE pin

transition time should be 10µs or less.

Programming the EEPROM

To program the non-volatile EEPROM, pull the CTL pin above 4.9V

for more than 200µs. The level and timing is shown in Figure 9. It

then takes a maximum of 100ms after CTL crosses 4.9V for the

programming to be completed inside the device.

When the part is programmed, the data in the counter register is

written into the EEPROM. This value will be loaded from the

EEPROM during subsequent power-ups as well as when the CE

pin is pulled low. The ISL24202 is factory-programmed to

mid-scale. As with asserting CE, the first pulse after a program

operation is ignored. The EEPROM contents can be written and

verified using the following steps:

1. Power-up the ISL24202. The EEPROM value will be loaded.

value, noting that first pulse will be ignored.

4. Pull the CTL pin to 4.9V or higher for at least 200µs. The

counter value will be written to EEPROM after 100ms.

noting that first pulse after programming will be ignored.

6. Set the CE pin to 0V. The stored output value will be loaded

from EEPROM after 10ms.

7. Verify that the output value is the same value programmed in

Step 4.

The CTL pin should be left floating after programming. The

that no additional pulses will be seen by the Up/Down counter. To

prevent further changes, ground the CE pin.

Typical Application Circuit

Shown below in Figure 10 is a typical circuit that can be used to

program the ISL24202 via the up/down counter interface. Three

momentary push-button switches are required. SW1 connected

and SW3 connected to GND to pull CTL to down. All the switches

For adjustment and programming to occur, the CE pin has to be

Note that pressing the UP button increments the counter, but

increasing.

CTL VOLTAGE

TIME

4.9V

FIGURE 9. EEPROM PROGRAMMING

>200µs

100ms

EEPROM

OPERATION

COMPLETE

FIGURE 10. TYPICAL APPLICATION CIRCUIT

ISL24202

CTL

0.01µF

1kΩ

CLOSE TO

UP

PROGRAM

1kΩ

DOWN

1kΩ

EEPROM

CE

SET

OUT

SW2

SW1

SW3

SW4

GND

0.01µF

0.1µF

0.1µF

ENABLE

ADJUST /

PROGRAM

DISABLE

EL5411T