ADM1178 Analog Devices, ADM1178 Datasheet - Page 23

• Manufacturer Part Number: ADM1178
• Description: Hot Swap Controller and Digital Power Monitor with ALERTB Output
• Manufacturer: Analog Devices

Specifications of ADM1178

• Operating Range(v): 3.15 to 16.5
• Uv & Ov Detection: ON pin (UV)
• Digital V & I Readback: I2C Interface,w/ 4 Addreses
• I Monitor Accuracy (+/-%): 2%
• Other Outputs: ALERTB
• Package: 10-Lead MSOP

ALERTB OUTPUT
The ALERTB output is an open-drain pin with 30 V tolerance.
This output can be used as an overcurrent flag by connecting it
to the general-purpose logic input of a controller. During normal
operation, this output is pulled high. (An external pull-up resistor
should be used because this is an open-drain pin.) When an over-
current condition occurs, the ADM1178 pulls this output low.
If any of the enabled latched alerts in the status byte (ADC_ALERT,
HS_ALERT, and OFF_ALERT) are triggered, the ALERTB output
asserts. For a programmable ADC-based overcurrent limit level
point, the ADC_ALERT latch must be enabled. The overcurrent
threshold that triggers an alert is then programmed via the
ALERT_TH register.
3.15V TO 16.5V
Figure 49. Using the ALERTB Output as an Interrupt
TIMER
ON
VCC
ADM1178
R
GND
SENSE
ALERTB
SENSE
GATE
SDA
ADR
SCL
N-CHANNEL FET
SDA
SCL
INTERRUPT
CONTROLLER
P = VI
Rev. C | Page 23 of 24
KELVIN SENSE RESISTOR CONNECTION
When using a low value sense resistor for high current meas-
urement, the problem of parasitic series resistance may arise.
The lead resistance can be a substantial fraction of the rated
resistance, making the total resistance a function of lead length.
This problem can be avoided by using a Kelvin sense connection.
This type of connection separates the current path through the
resistor and the voltage drop across the resistor. Figure 50 shows
the correct way to connect the sense resistor between the VCC pin
and the SENSE pin of the ADM1178.
KELVIN SENSE TRACES
CURRENT
FLOW FROM
SUPPLY
Figure 50. Kelvin Sense Connections
ADM1178
SENSE RESISTOR
VCC
SENSE
ADM1178
CURRENT
FLOW TO
LOAD