DC1193A - Demo Manual

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1193
TRIPLE DC/DC CONVERTER
LTC3545/-1
DESCRIPTION
Demonstration circuit 1193 is a triple output regulator
consisting of three constant-frequency step-down
converters integrated into LTC3545/-1. DC1193 has
an input voltage range of 2.25V to 5.5V, with regulators capable of delivering 800mA of load current on
each output. The three regulators operate independently with individual RUN pins and enter pulse skipping mode at low loads for reducing output ripple. In
shutdown, the DC1193 draws less than 1uA total. The
DC1193 is a very efficient circuit with efficiency reading above 90%. The LTC3545 comes in a 16-pin QFN
package, which has an exposed pad on the bottomside of the IC for better thermal performance. High
operating frequency of 2.25MHz allows exclusive use
of the small size, low profile surface mount components. These features plus internal compensation circuits, make the DC1193 demo board an ideal circuit
for use in battery-powered, hand-held applications.
DC1193A-A is a demoboard for LTC3545 and
DC1193A-B is a demoboard for LCT3545-1.
Design files for this circuit board are available. Call
the LTC factory.
LTC is a trademark of Linear Technology Corporation
Table 1. Performance Summary (TA = 25°C)
PARAMETER
CONDITIONS
VALUE
Minimum Input Voltage
2.25V
Maximum Input Voltage
5.5V
Output Voltage Regulation VOUT1
VIN = 2.25V to 5.5V, IOUT = 0A to 800mA
1.8V ±2%
Typical Output Ripple VOUT1
VIN = 4V, IOUT = 800mA (20 MHz BW)
<15mVP–P
Output Voltage Regulation VOUT2
VIN = 2.25V to 5.5V, IOUT = 0A to 800mA
1.2V ±2%
Typical Output Ripple VOUT2
VIN = 4V, IOUT = 800mA (20 MHz BW)
<15mVP–P
Output Voltage Regulation VOUT3
VIN = 2.25V to 5.5V, IOUT = 0A to 800mA
1.5V ±2%
Typical Output Ripple VOUT3
VIN = 4V, IOUT = 800mA (20 MHz BW)
<15mVP–P
Nominal Switching Frequency
2.25 MHz
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QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1193
TRIPLE DC/DC CONVERTER
QUICK START PROCEDURE
Demonstration Circuit 1193 is easy to set up to evaluate the performance of the LTC3545/-1. For proper
measurement equipment configuration, set up the
circuit according to the diagram in Figure 1.
NOTE: When measuring the input or output voltage
ripple, care must be taken to avoid a long ground lead
on the oscilloscope probe. Measure the input or output voltage ripple by touching the probe tip directly
across the VIN or VOUT and GND terminals. See the
Measurement Equipment Set-up diagram in Figure 2
for proper scope probe technique.
1.
Connect the input power supply to the VIN
and GND terminals. Connect the loads between the matching VOUT and GND terminals.
Refer to Figure 1 for the proper measurement
equipment setup. Make sure that loads on
outputs VOUT1 to VOUT3 do not exceed
800mA, on each output (all three outputs can
be loaded at the same time)
2.
Apply 5V at VIN and than insert RUN jumper
shunts JP1 through JP3 into the ON positions.
3.
Measure all four outputs VOUT1 through
VOUT3; they should read 1.8V, 1.2V and 1.5V
correspondingly. All output voltages should
be within +/- 2% tolerance.
4.
Vary the input voltage from 5.5V to 2.25V; all
four output voltages should be within +/- 2%
tolerance.
5.
Vary the VOUT1 load current from 0 to
800mA. Each output voltage should be within
a tolerance of +/- 2%.
6.
Vary the VOUT2 load currents from 0 to
800mA. Each output voltage should be within
a tolerance of +/- 2%.
7.
Vary the VOUT3 load current from 0 to
800mA. Each output voltage should be within
a tolerance of +/- 2%.
8.
To turn either output off set corresponding
jumper into OFF position.
For DC1193A-A only
To synchronize converter to external clock move
jumper J4 to Sync position (contacts 1 and 2) and
apply synchronization pulses in 1MHz to 3MHz frequency range to SYNC pin, see datasheet LTC3545
for details. For converter to operate in Pulse skipping
mode move jumper J4 to Pulse Skip position (contacts 2 and 3). For converter to operate in Burst mode
move jumper J4 into Burst position (contacts 3 and
4).
Warning - If the power for the demo board is carried
in long leads, the input voltage at the part could
“ring”, which could affect the operation of the converter. To eliminate the ringing, insert a small tantalum capacitor (for instance, AVX part #
TAJW686M010) on the pads between the input power
and return terminals on the bottom of the demo
board. The (greater) ESR of the tantalum will
dampen the (possible) ringing voltage due to the use
of long input leads. On a normal, typical PCB, with
short traces, the capacitor is not needed.
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QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1193
TRIPLE DC/DC CONVERTER
Figure 1. Proper Measurement Equipment Setup
Figure 2. Measuring Input or Output Ripple
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QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1193
TRIPLE DC/DC CONVERTER
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