MAX16050 Datasheet, PDF (14/22 Pages) Maxim Integrated Products – Voltage Monitors/Sequencer Circuits with Reverse-Sequencing Capability

Voltage Monitors/Sequencer Circuits with
Reverse-Sequencing Capability
When all of these conditions are met, the device starts
the power-sequencing process by turning on
OUT1–OUT_ in the sequence order. The sequence
delay between each OUT_ is the time required for the
power-supply voltage to exceed the undervoltage
threshold plus the additional time delay set by the
external delay capacitor; if no capacitor is connected to
the sequence delay timing input (DELAY), only a short
propagation delay (10µs) occurs. As each voltage
meets its respective threshold, the next OUT_ in the
sequence goes high impedance (open-drain output),
allowing the next power supply to turn on, which is then
monitored by the next input stage. When all of the volt-
ages exceed their respective thresholds, the reset out-
put (RESET) deasserts after a reset timeout period to
allow the system controller to start operating.
After sequencing is complete, if any SET_ input drops
below its threshold, a fault is detected. All power sup-
plies are simultaneously turned off by the OUT_ outputs
asserting low, the RESET output asserting, the DISC_
current pulldown turning on, and the FAULT output
pulling low for at least 1.9µs. The MAX16050/MAX16051
will then be ready to power on again. Sequencing
begins as soon as the four startup conditions are met.
Sequencing
The MAX16050 features three three-state sequence
logic inputs that select one of the 24 possible
sequence orders (Table 1). These inputs allow the
sequence order to be changed even after the board
layout is finalized. The MAX16051 offers five channels
and the device powers up in a fixed order from OUT1
to OUT5.
Table 1. MAX16050 Sequencing Table Logic
SEQ1
High-Z
High-Z
High-Z
High-Z
High-Z
High-Z
High-Z
High-Z
High-Z
Low
Low
Low
Low
Low
Low
Low
Low
Low
High
High
High
High
High
High
SEQ2
High-Z
High-Z
High-Z
Low
Low
Low
High
High
High
High-Z
High-Z
High-Z
Low
Low
Low
High
High
High
High-Z
High-Z
High-Z
Low
Low
Low
SEQ3
High-Z
Low
High
High-Z
Low
High
High-Z
Low
High
High-Z
Low
High
High-Z
Low
High
High-Z
Low
High
High-Z
Low
High
High-Z
Low
High
FIRST SUPPLY
OUT1
OUT1
OUT1
OUT1
OUT1
OUT1
OUT2
OUT2
OUT2
OUT2
OUT2
OUT2
OUT3
OUT3
OUT3
OUT3
OUT3
OUT3
OUT4
OUT4
OUT4
OUT4
OUT4
OUT4
SEQUENCE ORDER
SECOND SUPPLY THIRD SUPPY
OUT2
OUT3
OUT2
OUT4
OUT3
OUT2
OUT3
OUT4
OUT4
OUT2
OUT4
OUT3
OUT1
OUT3
OUT1
OUT4
OUT3
OUT1
OUT3
OUT4
OUT4
OUT1
OUT4
OUT3
OUT1
OUT2
OUT1
OUT4
OUT2
OUT1
OUT2
OUT4
OUT4
OUT1
OUT4
OUT2
OUT1
OUT2
OUT1
OUT3
OUT2
OUT1
OUT2
OUT3
OUT3
OUT1
OUT3
OUT2
FOURTH SUPPLY
OUT4
OUT3
OUT4
OUT2
OUT3
OUT2
OUT4
OUT3
OUT4
OUT1
OUT3
OUT1
OUT4
OUT2
OUT4
OUT1
OUT2
OUT1
OUT3
OUT2
OUT3
OUT1
OUT2
OUT1
14 ______________________________________________________________________________________