
ADM1041
THEORY OF OPERATION
POWER MANAGEMENT
This block contains V DD undervoltage lockout circuitry and a
power-on/reset function. It also provides precision references
for internal use and a buffered reference voltage, V REF . If V REF is
configured to an output pin, overloading, shorting to ground, or
shorting to V DD do not effect the internal references. See
Figure 8.During power-on, V REF does not come up until V DD exceeds the
upper UVL threshold. Housekeeping functions in this block
include reference voltage monitors, V DD overvoltage, and a
ground fault detector.
The ground fault detector monitors ADM1041 ground with
respect to the remote sense pin V S ?. If GND becomes positive
V REF 18
V DD 1
with respect to V S ? an on-chip signal, V DD OK, goes false. V DD OK
is true only when all the following conditions are met: ground is
negative with respect to V S ?, INTREF and EXTREF are operating
normally, V DD > UVLHI, and V DD < V DD OVP threshold.
GAIN TRIMMING AND CONFIGURATION
The various gain settings and configurations throughout the
ADM1041 are digitally set up via the SMBus after it has been
loaded onto its printed circuit board. There is no need for
external trim potentiometers. An initial adjustment process
should be carried out in a test system. Other adjustments such
as current sense and voltage calibration should be carried out in
the completed power supply.
INTERNAL
REFERENCE
2.5V
MAIN
BAND GAP
1.25V
EXTREFOK
REFERENCE
MONITOR
AUXILIARY
REFERENCE
INTREFOK
2.0V
4.0V
POR
UVLLO
S
RESET
4.4V
6.0V–6.5V
UVLHI
OVP
R
S
Q
Q
V DD OK
V DD OV
10 μ s–20 μ s
V S – 20
0.2V
GROUND
MONITOR
GNDOK
R
Q
GND 7
gndok_dis
Figure 8. Block Diagram of Power Management Section
Rev. A | Page 19 of 64