Instruction Manual

0V to 16V, Dual Hot-Swap Controller with 10-Bit
Current and Voltage Monitor and 4 LED Drivers
MAX5970
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Table 45. Force-On Control Register Format
Table 47. Undervoltage Status Register Format
Table 46. Force-On Key Register Format
Force-On Function
When the force-on bit for a channel is set to 1 in register
foset[1:0] (see Table 45), the channel is enabled regard-
less of the ON_ voltage or the Chx_EN1 and Chx_EN2
bits in register chxen. In forced-on operation, all func-
tions operate normally with the notable exception that the
channel does not shut down due to any fault conditions
that may arise.
There is a Force-On Key register fokey that must be set
to 0xA5 in order for the Force-On function to become
active (see Table 46). If this register contains any value
other than 0xA5, writing 1 to the Force-On bits in regis-
ter foset has no effect. This provides protection against
accidental force-on operation that might otherwise be
caused by an erroneous I
2
C write.
Fault Logging and Indications
The MAX5970 provides detailed information about any
fault conditions that have occurred. Independent FAULT_
outputs specifically indicate circuit-breaker shutdown
events, while an ALERT output is asserted whenever a
problem has occurred that requires attention or interaction.
Fault Dependency
If a fault event occurs (digital UV warning/critical, digital
OV warning/critical, or digital overcurrent warning), the
fault is logged by setting a corresponding bit in registers
fault1 or fault2 (see Tables 47, 48, and 49).
Description: Force-on control register
Register Title: foset
Register Address: 0x3A
R R R R R R R/W R/W
RESET
VALUE
0 0 0 0 0 0 Ch1_fo Ch_fo 0x00
bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
Description: Force-on key register (must contain 0xA5 to unlock force-on feature)
Register Title: fokey
Register Address: 0x39
R/W R/W R/W R/W R/W R/W R/W R/W
RESET
VALUE
fokey[7] fokey[6] fokey[5] fokey[4] fokey[3] fokey[2] fokey[1] fokey[0] 0x00
bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
`
Undervoltage digital-compare status register (warning [1:0] and critical [5:4] undervoltage event
detection status)
Register Title: fault0
Register Address: 0x35
R R R/C R/C R R R/C R/C
RESET
VALUE
— — ch1_uv2 Ch0_uv2 — — Ch1_uv1 Ch0_uv1 0x00
bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0