ADM1073 Analog Devices, ADM1073 Datasheet - Page 13

• Manufacturer Part Number: ADM1073
• Description: -48 V Full Feature Hot Swap Controller
• Manufacturer: Analog Devices

Specifications of ADM1073

• I Control Accuracy %: 3%
• Other Inputs: RESTARTb,SHDNb
• Other Outputs: LATCHEDb,PWRGDb,SPLYGDb
• Package: 14-ld TSSOP
• Vin Min (v): -18V
• Vin Max (v): -80V
• Uv & Ov Detection: UV pin, OV pin

Data Sheet
FUNCTIONAL DESCRIPTION
HOT CIRCUIT INSERTION
Inserting circuit boards into a live −48 V backplane can cause
large transient currents to be drawn as the board capacitance
charges up. These transient currents can cause glitches on the
system power supply and can permanently damage the board
connectors and components.
The ADM1073 is designed to control the manner in which a
board’s supply voltage is applied so that harmful transient
currents do not occur and the board can be safely inserted or
removed from a live backplane. Undervoltage, overvoltage, and
overcurrent protection are other features of the part. The
ADM1073 ensures that the input voltage is stable and within
tolerance before being applied to the power module.
BACKPLANE
–48V RTN
+48V
LIVE
R1
R2
–48V
0V
R
*R
TIMER
TIMER
C
SS
R3
R4
*
IS AN OPTIONAL COMPONENT
R1
R2
C
TIMER
TIMER
R
OV
UV
SS
DROP
R3
R4
C
V
SHDN
TIMER CONTROL
UNDERVOLTAGE
SS
IN
OVERVOLTAGE
GENERATOR
REFERENCE
SOFT START
SHUTDOWN
DETECTOR
DETECTOR
5 SECOND
R
CONTROL
V
DROP
CC
V
EE
AND
Figure 32. ADM1073 Application Diagram
C
RESTART
TIMER
Figure 31. ADM1073 Topology
ADM1073
R
OSCILLATOR
SHDN
Rev. A | Page 13 of 24
SENSE
100mV(MAX)
AND CONTROL
FAULT TIMER
RESTART
PLUG-IN BOARD
FET
SPLYGD
AND PWRGD
TIMEOUT
FOLDBACK
PWM
INITIAL STARTUP
The ADM1073 hot swap controller normally resides on a
removable circuit board and controls the manner in which
power is applied to the board upon connection. This is achieved
using a FET, Q1, in the power path (see Figure 31). By
controlling the gate voltage of the transistor, the surge of current
to charge load capacitance can be limited to a safe value when
the board makes connection. The ADM1073 can also reside on
the backplane itself and perform the same function from there.
Figure 32 shows a typical ADM1073 application circuit. When
the plug-in board is inserted into the live backplane, the −48 V
and 0 V lines connect to the live supply. This powers up the
device with the voltage on V
voltage on the UV pin exceeds the undervoltage rising
threshold (0.868 V), it is now inside the programmed operating
voltage window. It must stay inside this window for the duration
of the power-on reset delay time, t
R
DRAIN
LATCHED
LATCHED
SPLYGD
PWRGD
50mA
V
IN
DRAIN
GATE
SENSE
V
PWRGD
EE
R
DRAIN
FET
R
SENSE
C
CONVERTER
LOAD
DC-DC
V
V
CONVERTER
IN
IN
IN
+
–
DC-DC
exceeding V
POR
5V
3.3V
2.8V
...etc.
GND
(150 ms).
LKO
. When the
ADM1073