Rainbow Electronics MAX6871 - Manual (Page 45)

Applications Information
Configuration Download at Power-up
The configuration of the MAX6870/MAX6871 (undervolt-
age/overvoltage thresholds, PO_ timeout periods,
watchdog behavior, programmable output conditions
and configurations, etc.) depends on the contents of
the EEPROM. The EEPROM is comprised of buffered
latches that store the configuration. The local volatile
memory latches lose their contents at power-down.
Therefore, at power-up, the device configuration must
be restored by downloading the contents of the EEP-
ROM (non-volatile memory) to the local latches. This
download occurs in a number of steps:
1) Programmable outputs go high impedance with no
power applied to the device.
2) When ABP exceeds +1V, all programmable out-
puts are weakly pulled to GND through a 10µA
current sink.
3) When ABP exceeds UVLO, the configuration EEP-
ROM starts to download its contents to the volatile
configuration registers. The programmable outputs
assume their programmed conditional output state
when download is complete.
4) Any attempt to communicate with the device prior to
this download completion results in a NACK being
issued from the MAX6870/MAX6871.
MAX6870/MAX6871
EEPROM-Programmable Hex/Quad
Power-Supply Sequencers/Supervisors with ADC
______________________________________________________________________________________ 45
Table 30. Configuration Lock Register
REGISTER
ADDRESS
EEPROM
MEMORY
ADDRESS
BIT
RANGE
DESCRIPTION
[0]
0 = configuration unlocked.
1 = configuration locked.
45h 8045h
[7:1] Not used.
Table 31. Write Disable Register
REGISTER
ADDRESS
EEPROM
MEMORY
ADDRESS
BIT
RANGE
DESCRIPTION
[0]
0 = write not disabled if PO1 asserts (MAX6870).
1 = write disabled if PO1 asserts (MAX6870). Set to 0 (MAX6871).
[1]
0 = write not disabled if PO2 asserts (MAX6870).
1 = write disabled if PO2 asserts (MAX6870). Set to 0 (MAX6871).
[2]
0 = write not disabled if PO3 (MAX6870)/PO1 (MAX6871) asserts.
1 = write disabled if PO3 (MAX6870)/PO1 (MAX6871) asserts.
[3]
0 = write not disabled if PO4 (MAX6870)/PO2 (MAX6871) asserts.
1 = write disabled if PO4 (MAX6870)/PO2 (MAX6871) asserts.
[4]
0 = write not disabled if PO5 (MAX6870)/PO3 (MAX6871) asserts.
1 = write disabled if PO5 (MAX6870)/PO3 (MAX6871) asserts.
[5]
0 = write not disabled if PO6 (MAX6870)/PO4 (MAX6871) asserts.
1 = write disabled if PO6 (MAX6870)/PO4 (MAX6871) asserts.
[6]
0 = write not disabled if PO7 (MAX6870)/PO5 (MAX6871) asserts.
1 = write disabled if PO7 (MAX6870)/PO5 (MAX6871) asserts.
43h 8043h
[7]
0 = write not disabled if PO8 asserts (MAX6870).
1 = write disabled if PO8 asserts (MAX6870). Set to 0 (MAX6871).