HV300DB1
HV300DB1
HV300 Hot Swap Demo Board
Introduction
The HV300DB1 demonstration board contains all of the circuitry
necessary to safely hot-plug a -48V peripheral into a live
backplane. The electrolytic capacitor, Cload simulates the input
filter capacitor of a DC-to-DC converter. Cload should be
removed if an actual DC-to-DC converter is being used as the
load.
Specifications
Input voltage range
Undervoltage lockout
Overvoltage lockout
Maximum continuous load current
Switch resistance
Current sense resistance
35V to 65V
35V
65V
1.7A
0.21Ω
0.05Ω
Board Layout and Connections
VDD
VDD
68kΩ
48V
PG
Drain
VEE
Load
Optional
V
DD
Input and Output
V
DD
is the positive power supply terminal. It is also connected
to the output load. Resistors, R1, R2, and R3 are chosen to
allow for an operating input range of 35V to 65V. The HV300LG
is capable of operating up to 90V.
resistor connected from V
DD
to PG is acceptable. Normally PG
would be connected to an enable input on a DC-to-DC converter
power supply.
UV and OV Test Point
Voltages on these test points sets the under voltage and over
voltage values. These test points can be probed to examine the
divided down values set by R1, R2 and R3. The window
comparator works around 1.21V nominally with 100mV of
hysteresis.
V
EE
Input
Vee is the negative power supply terminal. MOSFET, M1 is
used to connect and disconnect V
EE
to the drain output.
Drain Output
This is the negative side for the output load. V
EE
is connected
to this pin via MOSFET M1 controlled by the HV300LG.
Ramp Test Point
This test point provides access to the ramp capacitor’s positive
terminal, which is used to program the hot swap timing profile.
PG Test Point
PG is the Power Good (PWRGD) test point, which is an open
drain N-channel MOSFET with “ok” high logic. An external pull
up resistor should be connected to this point. PG can withstand
pull up voltages of up to 90V. To examine PG operation, a
Gate Test Point
This is the gate voltage on MOSFET M1. The HV300LG
modulates the resistance M1 by controlling its gate profile. This
test point allows examination of the gate voltage.
05/16/01
Supertex Inc. does not recommend the use of its products in life support applications and will not knowingly sell its products for use in such applications unless it receives an adequate "products liability
indemnification insurance agreement." Supertex does not assume responsibility for use of devices described and limits its liability to the replacement of devices determined to be defective due to
workmanship. No responsibility is assumed for possible omissions or inaccuracies. Circuitry and specifications are subject to change without notice. For the latest product specifications, refer to the
Supertex website: http://www.supertex.com. For complete liability information on all Supertex products, refer to the most current databook or to the Legal/Disclaimer page on the Supertex website.
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