DC543A - Demo Manual

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 543
LTC2920 WITH DUAL DC TO DC CONVERTER
LTC2920-2
DESCRIPTION
Demonstration circuit 543 is an LTC®2920-2 Dual
Voltage Margining Controller integrated with an
LTC1628 Dual High Efficiency, 2-Phase Synchronous
Step-Down Switching Regulator. Two 3-position
switches are provided to demonstrate both high and
low voltage margining. The switches margin the 5.0V
and 3.3V outputs to ±10% of their nominal values.
By changing jumpers a slower raise and fall time be-
tween margined and un-margined voltages can be
demonstrated. The total PCB footprint used by the
LTC2920-2 and all of its associated components is
less than .05 in².
Design files for this circuit board are available. Call
the LTC factory.
LTC is a Registered trademark of Linear Technology Corporation
Table 1. Performance Summary
PARAMETER
CONDITION
MIN
Input Voltage Range
TYP
7
MAX
UNITS
24
V
Output Voltage VOUT1
5
V
Output Voltage VOUT2
3.3
V
Voltage Margining
± 10
%
Output Current IOUT
10
12
A
QUICK START PROCEDURE
The circuit is very simple as far as the basic input and
output connections are concerned, see Figure 1.
However, due to the high current nature of this design, care must be exercised or unreliable results will
be obtained. The first consideration is the wire gauge
for input and output power connections. The load
current of 12A will require at least 3 strands of AWG
18 wire or equivalent for the output power and
ground connections. The input wire size is 1 to 3
strands of AWG 18 or equivalent, depending on the
input voltage. There is one pair of connector terminals for the inputs of the DC543 and one pair for each
output. It is important that all these connections be
tightened and secured before applying power to the
circuit.
The lab supply used for the input source of DC543
must be capable of supplying a current estimated at
1.2 x (VO1 x IO1 + VO2 x IO2)/VIN. Use a lab power
supply with a voltage between 7 and 24 Volts. To prevent interaction between the lab supply and the demo
board, additional low impedance electrolytic capacitors at the output of the lab supply are recommended.
This is particularly important for transient load testing, especially at low input voltages.
Connect a resistive load to the output terminals of the
DC543. For the 5V supply, connect a load resistor between the two output terminals with a value between
0.5 ohms and 50 ohms. For the 3.3V supply, connect
a load resistor between the two output terminals with
a value between 0.33 ohms and 33 ohms. Be sure to
calculate the power dissipation in each resistor and
select resistors with a high enough constant power
rating. The demo board is shipped with the following
settings:
JP1 (FCB)
INTVcc
JP2 (STBYMD)
0’
JP3 (FLTCPL)
INTVcc
JP6 (RUN1)
‘1’
1
QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 543
LTC2920 WITH DUAL DC TO DC CONVERTER
JP7 (RUN2)
‘1’
JP8 (Damped)
Normal
JP9 (Damped)
Normal
tion will cause the associated output voltage to be
10% lower than the nominal voltage.
Attach the voltmeters directly to the input and output
connectors to measure the input voltage and output
voltage, respectively. Place the two ‘3 position’
switches, SW1 and SW2 in the middle position. Turn
on the power supply connected to the Vin terminals
and verify the nominal voltages at the Vin terminals
and both sets of output terminals.
SW2 controls the 5 Volt output, SW1 controls the 3.3
Volt output. Moving a switch to the ‘0’ position will
cause the associated output voltage to be 10% higher
than nominal voltage. Moving a switch to the ‘1’ posi-
2
QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 543
LTC2920 WITH DUAL DC TO DC CONVERTER
Figure 1. Proper Measurement Equipment setup
3
QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 543
LTC2920 WITH DUAL DC TO DC CONVERTER
4
Similar pages