X1228 データシートの表示（PDF） - Intersil

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X1228

4K (512 x 8), 2-Wire™ RTC

Intersil 

X1228

Figure 5. Set VTRIP Level Sequence (VCC = desired VTRIP value)

RESET

VCC

SCL

0 1 23 4 56 7

VP = 15V

01 23 4 56 7

01 23 4 56 7

VCC

01 23 4 56 7

SDA

AEh

00h

Note: BP0, BP1, BP2 must be disabled.

01h

00h

Resetting the VTRIP Voltage

This procedure is used to set the VTRIP to a “native”

voltage level. For example, if the current VTRIP is 4.4V

and the new VTRIP must be 4.0V, then the VTRIP must

be reset. When VTRIP is reset, the new VTRIP is some-

thing less than 1.7V. This procedure must be used to

set the voltage to a lower value.

To reset the new VTRIP voltage, apply more than 5.5V

to the VCC pin and tie the RESET pin to the

programming voltage VP. Then write 00h to address

03h. The stop bit of a valid write operation initiates the

VTRIP programming sequence. Bring RESET to VCC to

complete the operation. Note: this operation takes up

Figure 6. Reset VTRIP Level Sequence

to 10 milliseconds to complete and also writes 00h to

address 03h of the EEPROM array.

For best accuracy in setting VTRIP, it is advised that

the following sequence be used.

1.Program VTRIP as above.

2.Measure resulting VTRIP by measuring the VCC

value where a RESET occurs. Calculate Delta =

(Desired – Measured) VTRIP value.

3.Perform a VTRIP program using the following formula

to set the voltage of the RESET pin:

VRESET = (Desired Value – Delta) + 0.025V

RESET

VCC

SCL

VP = 15V

VCC

0 1 23 4 56 7

01 23 4 56 7

01 23 4 56 7

01 23 4 56 7

SDA

AEh

00h

03h

00h

Note: BP0, BP1, BP2 must be disabled.

17

FN8100.4

May 18, 2006

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