MAX16050 Datasheet, PDF (17/22 Pages) Maxim Integrated Products – Voltage Monitors/Sequencer Circuits with Reverse-Sequencing Capability

Voltage Monitors/Sequencer Circuits with
Reverse-Sequencing Capability
Daisy-Chaining the MAX16050/MAX16051
The MAX16050/MAX16051 can be daisy-chained to
sequence and monitor a large number of voltages
(Figure 7). When a fault occurs on any of the monitored
inputs, FAULT goes low, signaling a fast power-down.
Connect all FAULT pins of the MAX16050/MAX16051
together to ensure that all power supplies are turned off
during a fault.
In Figure 7, SHDN is pulled low to initiate the power-
down sequence. When all of the supply voltages moni-
tored by U2 are off, the bus removal output (REM) goes
high, thereby allowing U1 to start sequencing down.
REM normally is at a logic-low state when all voltages
are good. Connect U2’s REM to U1’s EN_HOLD to
force U1 to stay on even if EN and SHDN are pulled
low. This enable-and-hold circuitry allows the system to
power down correctly.
MOSFET Selection
The external pass MOSFET connects in series with the
sequenced power-supply source. Since the load cur-
rent and the MOSFET drain-to-source impedance
(R_DSON) determine the voltage drop, the on-character-
istics of the MOSFET affect the load supply accuracy.
For highest supply accuracy and lowest voltage drop,
select a MOSFET with an appropriate drain-to-source
on-resistance with a gate-to-source bias of 4.5V to 6.0V
(see Table 2).
Layout and Bypassing
For better noise immunity, bypass V_CC to GND with a
0.1µF capacitor installed as close to the device as pos-
sible. Bypass ABP to GND with a 1µF capacitor
installed as close to the device as possible; ABP is an
internally generated voltage and must not be used to
supply more than 1mA to external circuitry. Connect the
exposed pad (EP) to the ground plane for improved
heat dissipation. Do not use EP as the only ground con-
nection for the device.
Table 2. Recommended MOSFETs
MANUFACTURER
PART
V_DS
(V)
V_GSth R_DSON AT V_GS = 4.5V
I_MAX AT 50mV
Qg (nC)
(V)
(mΩ)
VOLTAGE DROP (A) (TYP)
FOOTPRINT
FDC633N
30 0.67
42
1.19
11
Super
SOT^TM-6
Fairchild
FDP8030L
FDB8030L
30
1.5
4.5
FDD6672A
30
1.2
9.5
FDS8876
30
2.5
(max)
17
11.11
5.26
2.94
120
TO-220
TO-263AB
33
TO-252
15
SO-8
Si7136DP
20
3
4.5
Si4872DY
30
1
10
Vishay
SUD50N02-09P 20
3
17
11.11
5
2.94
24.5
SO-8
27
SO-8
10.5
TO-252
Si1488DH
20 0.95
49
1.02
6
SOT-363
SC70-6
IRL3716
20
3
4.8
TO220AB
10.4
53
D²PAK
TO-262
IRL3402
20
0.7
10
International
Rectifier
IRL3715Z
20
2.1
15.5
5
78 (max) TO-220AB
TO220AB
3.22
7
D²PAK
TO-262
IRLML2502
20
1.2
45
1.11
8
SOT23-3
Micro3^TM
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