MAX16050_08 Datasheet, PDF (13/21 Pages) Maxim Integrated Products – Voltage Monitors/Sequencer Circuits with Reverse-Sequencing Capability

Voltage Monitors/Sequencer Circuits with
Reverse-Sequencing Capability
Detailed Description
The MAX16050 monitors up to 5 voltages (Figure 5) with
the ability to sequence up to 4 voltages, while the
MAX16051 monitors up to 6 voltages with the ability to
sequence up to 5 voltages. These devices control sys-
tem power-up and power-down in a particular
sequence order. The MAX16050/MAX16051 turn off all
supplies and assert a reset to the processor when any
of the voltages falls below its respective threshold. The
MAX16050/MAX16051 offer an 85mA pulldown feature
that helps discharge the output capacitance of DC-DC
converters to ensure timely power-down. In addition, the
MAX16050/MAX16051 also reverse sequence, monitor-
ing each power-supply output voltage present at the
associated DISC_ input and ensuring that the voltage
falls below 250mV before turning off the next supply.
The MAX16050 provides three sequence logic inputs,
which select the sequence order from 24 possible
VBUS
DC-DC
EN
DC-DC
EN
DC-DC
EN
combinations (Table 1). In the default mode (SEQ1 =
SEQ2 = SEQ3 = High Impedance), the power-up
sequence is OUT1→OUT2→OUT3→OUT4. The
MAX16051 features an additional channel and the
sequence order is fixed at OUT1→OUT2→OUT3
→OUT4→OUT5. For complex systems with a large
number of power supplies, the MAX16050/MAX16051
can be used in a daisy-chain configuration. Reverse
sequencing in the daisy-chained configuration is still
possible.
The MAX16050/MAX16051 keep all OUT_ low (all of the
supplies in the off-state) until four conditions are met.
1) The voltage at ABP exceeds the undervoltage lock-
out threshold.
2) The voltage at the analog enable input (EN) is
above its threshold.
3) The shutdown input, SHDN, is not asserted.
4) All DISC_ voltages must be below 250mV.
V1
V2
V3
DC-DC
V4
EN
VPU
VCC
EN
ON
OFF
GND
SHDN
MAX16050
RESET
OV_OUT
FAULT
REM
Figure 5. Typical Connection for Sequencing Four DC-DC Converters
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