Linear Technology 461A-A User manual

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 461A-A&B
COMPACT PCI BUS HOT SWAP CONTROLLER & SYSTEM BACKPLANE
1
LTC1644CGN
DESCRIPTION
Demonstration circuit 461A-Ais a circuit board
which demonstrates an application of the
LTC®1644CGN Compact PCI Hot Swap Con-
troller. DC 461A-Bsimulates the backplane of
a Compact PCI Bus system. Together the demo
boards demonstrate the Hot Swap controller
and how it allows a board to be safely inserted
or removed from an active (powered) Compact
PCI (CPCI) bus slot. In addition to demonstrat-
ing the Hot Swap capability, the DC461A also
demonstrates the ability of the LTC1644CGN to
monitor, control and protect the +5, +3.3, +12
and -12 volt power supplies, and bias the I/O
pins for minimal disruption during card insertion
and extraction.
External N-channel transistors control the
3.3V/5V supplies, while on-chip switches con-
trol the –12V and 12V supplies. The 3.3V and
5V supplies can be ramped up at a program-
mable rate. Electronic circuit breakers protect
all four supplies against overcurrent faults. The
PWRGD output indicates when all of the supply
voltages are within tolerance. The OFF/ON pin
is used to cycle the board power or reset the
circuit breaker. The PRECHARGE output can
be used to bias the bus I/O pins during card in-
sertion and extraction. PCI_RST# is combined
on-chip with HEALTHY# in order to generate
LOCAL_PCI_RST#.
Design files for this circuit board are available.
Call the LTC factory.
, LTC and LT are registered trademarks of Linear Technology Cor-
poration
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QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 461A-A&B
COMPACT PCI BUS HOT SWAP CONTROLLER & SYSTEM BACKPLANE
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QUICK START PROCEDURE
Demonstration circuit 641A is easy to set up to evaluate the performance of the LTC1644CGN. The
DC641A- B board will be referred to as the backplane, and the DC641A- A will be referred to as the appli-
cation board.
Initial Setup
Place jumpers on the backplane board as follows:
JP1 JP2 JP3
GND +5V +5V
Connect the input +5, +3.3, +12 and -12 volt power supplies to the backplane board (See figure 1).
If you plan to test the circuit breaker and current limit features, make sure your power supplies are
capable of delivering at least 8 Amps at +5 volts, 10 Amps at +3.3Volts, 1 Amp at +12 Volts and
500mA at -12Volts.
POWER SUPPLY +
3.3 VDC _
+3.3V
GND
+5V
BD_SEL
I/O
PCI_RST#
HEALTHY#
GND
-12V
+12V
JP1
JP2
JP3
LTC1644CGN
12Vout GND Veeout 3Vout
GND
GNDI/ORESET#FAULT/
POWER SUPPLY -
5 VDC +
- +
POWER SUPPLY
12 VDC
- +
POWER SUPPLY
12 VDC
DC461A-A
BACKPLANE BOARD
DC461A-B
APPLICATION BOARD
5Vout
Figure 1- Power Supply Connections
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QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 461A-A&B
COMPACT PCI BUS HOT SWAP CONTROLLER & SYSTEM BACKPLANE
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Initial verification
Plug the application board into the backplane
and power up the input power supplies. Ob-
serve the LEDs. The green “HEALTHY” LED (D4
on backplane) should be ON indicating that the
input power supplies are good, The red power
LEDs (D1, D2, D5, and D7 on the application
board) should also be ON indicating that the
+12V, -12V, +5V and +3.3V power supplies are
operating. Measure the application board power
supply output voltages to verify that the proper
voltages are present.
HEALTHY# Function
Under voltage problems with the input power
supplies are detected and indicated. Slowly re-
duce the voltage of one input power supply.
Observe that the green HEALTHY LED goes out
when the input voltage drops below its power-
good threshold. Slowly return the voltage to its
nominal value. Observe that the green
HEALTHY LED comes back ON when the input
power is once again in the allowable range. Re-
peat the process on the 3 remaining input power
supplies if desired.
Precharging I/O pins Function
Upon application board insertion, the application
board I/O pin is precharged to the desired level
before the application circuitry is powered up.
Upon PCI connector extraction the precharge
voltage level is maintained until after the appli-
cation circuitry is powered down. Monitor the
voltage level (1 Volt) at the I/O testpoint.
Slowly unplug the application board from the
backplane and observe that the I/O pin remains
charged after the application board has been
removed far enough to cause the power supplies
to cut off. Slowly plug the application board into
the backplane and observe that the I/O pin
charges to 1 Volt before application board has
been inserted far enough to enable the applica-
tion power supplies.
Over Current Protection Function
The LTC1644 provides overcurrent protection for
all of its output supplies. The overcurrent fault
will trip the electronic circuit breaker causing the
LTC 1644 to latch off. Apply an adjustable load
to one of the application power supplies. Slowly
increase the load while monitoring the load cur-
rent. When the application board’s current limit
for that power supply is exceeded, the electronic
circuit breaker will activate and all application
power supplies will be cut off. Observe that
when the electronic circuit breaker activates the
green HEALTHY LED turns OFF, all 4 of the red
power LEDs turn OFF, and the red FAULT LED
turns ON. Repeat the process on the 3 remain-
ing power supply outputs if desired.
Short Circuit Protection Function
Unplug the application board from the backplane
and apply a short across any of the power sup-
ply outputs on the application board, then plug
it back into the backplane. Observe that the
green HEALTHY LED is now OFF, and all 4 of the
red power LEDs are OFF, and the red FAULT LED
is ON. Unplug the application board from the
backplane and remove the short, then plug it
back into the backplane. The Green “HEALTHY”
LED and the red power LEDs should come ON
again, and the red FAULT LED should be OFF.
You can also apply the short while the applica-
tion board is plugged into the backplane and
powered up with the same results and no spark-
ing or popping. Repeat the process on the 3
remaining application power supply outputs if
desired.
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QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 461A-A&B
COMPACT PCI BUS HOT SWAP CONTROLLER & SYSTEM BACKPLANE
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BD_SEL# Function
The application power supplies can be turned on
and off, and the latched fault condition cleared
by toggling the BD_SEL# signal. On the back-
plane board, set the BD_SEL (J1) to the N/C
(floating) position. The BD_SEL# signal is now
no longer grounded through the backplane so
the BD_SEL# is pulled high by circuitry on the
application board. Observe that when the
BD_SEL# testpoint goes low this enables the
application power supplies, and when BD_SEL#
goes high the application power supplies are dis-
abled (no LEDs ON). Force a fault condition by
momentarily applying a short to one of the ap-
plication board power supplies. Observe that the
application power supplies can be reset from a
faulted state (once the fault condition is re-
solved) by taking BD_SEL# hi then low again.
Fault/ Function
A fault response can be initiated by momentarily
taking the FAULT / testpoint low. The fault can
be cleared by taking BD_SEL# high then low
again.
PCI_RST# Function
When input power is good (HEALTHY LED is
ON), the PCI Reset signal from the backplane is
propagated to the Local PCI Reset line on the
application board. Alternately ground and allow
PCI_RST# on the backplane to be pulled high
while observing RESET# on the application
board board. RESET# follows PCI_RST#.
When input power is not good (HEALTHY LED is
OFF), RESET# is held low regardless of the state
of PCI_RST#. Reduce one of the input power
supplies until the HEALTHY LED turns OFF. Al-
ternately ground and allow PCI_RST# on the
backplane to be pulled high while observing
RESET# on the application board board.
RESET# stays low.
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QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 461A-A&B
COMPACT PCI BUS HOT SWAP CONTROLLER & SYSTEM BACKPLANE
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