MAX6877 Datasheet, PDF (1/24 Pages) Maxim Integrated Products – Dual-/Triple-Voltage, Power-Supply Trackers/Sequencers/Supervisors

19-3771; Rev 0; 7/05
Dual-/Triple-Voltage, Power-Supply
Trackers/Sequencers/Supervisors
General Description
The MAX6877/MAX6878/MAX6879 multivoltage power
trackers/sequencers/supervisors monitor up to three
system voltages and provide proper power-up and
power-down control for systems requiring voltage track-
ing or sequencing. These devices ensure controlled
voltage tracking within a specified range or sequencing
in the proper order as system power supplies are
enabled. The MAX6877/MAX6878/MAX6879 generate
all required voltages and timing to control up to three
external n-channel pass FETs for the OUT1/OUT2/
OUT3 supply voltages (see the Selector Guide for dif-
ferent features of each device).
The MAX6877/MAX6878/MAX6879 feature adjustable
undervoltage thresholds for each input supply. When all
the voltages are above these adjustable thresholds, the
devices turn on the external n-channel MOSFETs to
either sequence or track the voltages to the system.
During voltage-tracking mode, the voltage at the GATE
of each MOSFET is increased to slowly bring up all
supplies at a controlled slew rate. The MAX6877/
MAX6878/MAX6879 feature an autoretry or latch-off
mode with capacitor-adjusted timing.
These devices also provide a controlled power-down
(tracking mode) when the system shuts off in an orderly
manner. When an unexpected fault occurs, the outputs
are all pulled down simultaneously with an internal
100Ω pulldown to help discharge capactive loads at
the MOSFET’s source. The MAX6877/MAX6878/
MAX6879 feature independent internal charge pumps
to fully enhance the external FETs for low-voltage drop
at highpass current. The MAX6877 and MAX6878 also
feature a power-good output with a selectable timeout
period that can be used for system reset.
The MAX6877/MAX6878/MAX6879 are available in
small 4mm x 4mm 24-pin and 16-pin thin QFN pack-
ages and are fully specified over the -40°C to +85°C
extended operating temperature range.
Multivoltage Systems
Networking Systems
Telecom
Storage Equipment
Servers/Workstations
Applications
Selector Guide appears at end of data sheet.
Features
♦ Pin-Selectable Tracking or Sequencing Control
for Up to Three Supply Voltages
♦ Capacitor-Adjustable Power-Up/Down Tracking
Slew Rate
♦ Capacitor-Adjustable Power-Up Sequencing Delay
♦ Internal Charge Pumps to Enhance External
n-Channel FETs
♦ Capacitor-Adjustable Timeout Period Power-Good
Output (MAX6877/MAX6878)
♦ Adjustable Undervoltage Lockout or
Logic-Enable Input
♦ Internal 100Ω Pulldown for Each Output to
Discharge Capacitive Load Quickly
♦ 0.5V to 5.5V Nominal IN_/OUT_ Range
♦ 2.7V to 5.5V Operating Voltage Range
♦ Immune to Short Voltage Transients
♦ Small 4mm x 4mm 24-Pin or 16-Pin Thin QFN
Packages
Ordering Information
PART
TEMP RANGE
PIN-
PACKAGE
PKG
CODE
MAX6877ETG+ -40°C to +85°C 24 Thin QFN T2444-4
MAX6877ETG
-40°C to +85°C 24 Thin QFN T2444-4
Ordering Information continued at end of data sheet.
+Denotes lead-free package.
Pin Configurations
TOP VIEW
18 17 16 15 14 13
GATE2 19
12 TRK/SEQ
OUT1 20
11 LTCH/RTR
GATE1 21
IN3 22
MAX6877
IN2 23
EP*
+
IN1 24
12 3 4 5
10 TIMEOUT
9 SLEW
8 DELAY
7 GND
6
4mm x 4mm THIN QFN
*EXPOSED PADDLE CONNECTED TO GND.
Pin Configurations continued at end of data sheet.
________________________________________________________________ Maxim Integrated Products 1
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