ADM1087 Analog Devices, ADM1087 Datasheet - Page 14

• Manufacturer Part Number: ADM1087
• Description: Voltage Sequencer with Active Low, Open-Drain Enable Output
• Manufacturer: Analog Devices

Specifications of ADM1087

• # Supplies Monitored: 1
• Volt Monitoring Accuracy: 7%
• # Output Drivers: 1
• Fet Drive/enable Output: Enable
• Sequencing: Up
• Package: 6 ld SC70

ADM1085/ADM1086/ADM1087/ADM1088
QUAD-SUPPLY POWER GOOD INDICATOR
The enable output of the Simple Sequencers is equivalent to an
AND function of V
the voltage at V
(ENIN) is high as well. Although ENIN is a digital input, it can
tolerate voltages as high as 22 V and can detect if a supply is
present. Therefore, a simple sequencer can monitor two
supplies and assert what can be interpreted as a power good
signal when both supplies are present. The outputs of two
ADM1085s can be wire-AND’ e d together to make a quad-
supply power good indicator.
2.5V
1.8V
9V
5V
Figure 30. Quad-Supply Power Good Indicator
IN
is above the threshold and the enable input
IN
and ENIN. ENOUT is high only when
V
V
ENIN
ENIN
IN
IN
ADM1085
ADM1085
3.3V
3.3V
ENOUT
ENOUT
3.3V
POWER_GOOD
Rev. A | Page 14 of 16
SEQUENCING WITH FET SWITCHES
The open-drain outputs of the ADM1085 and ADM1087 can
drive external FET transistors that can switch on power supply
rails. All that is needed is a pull-up resistor to a voltage source
that is high enough to turn on the FET.
2.5V
12V
Figure 31. Sequencing with a FET Switch
V
ENIN
IN
ADM1085
3.3V
ENOUT
CEXT