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dc1596afa
DEMO MANUAL DC1596A
QUICK START PROCEDURE
The DC1596 is easy to set up to evaluate the performance
of the LTC3607. For a 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 V
IN
or V
OUT
and GND terminals. See the proper scope probe
technique in Figure 2.
Please follow the procedure outlined below for proper
operation.
1. Connect the input power supply to the PVIN1/PVIN2 and
GND terminals (V
IN1
and V
IN2
are separate nodes but
are connected). Connect the loads between the VOUT
and GND terminals. Refer to Figure 1 for the proper
measurement equipment setup.
Before proceeding to operation, insert jumper shunts
XJP1 and XJP2 into the OFF positions of headers JP1
and JP2, shunt XJP3 into the pulse-skip position of
MODE header JP3, and shunt XJP4 into the VOUT1
voltage options of choice of header JP4: 1.2V, 1.5V, or
1.8V, and shunt XJP5 into the VOUT2 voltage options
of choice of header JP5: 2.5V, 3.3V, or 5V.
2. Apply 5.5V at PVINs 1, 2. Measure both VOUTs; they
should read 0V. If desired, one can measure the shut-
down supply current at this point. The supply current
will be less than 1µA in shutdown.
3. Turn on VOUT1 and VOUT2 by shifting shunts XJP1
and XJP2 from the OFF positions to the ON positions.
Both output voltages should be within a tolerance of
±2%.
4. Vary the input voltages from 5.8V (the minimum V
IN
is
dependent on V
OUT
) to 15V, and the load currents from
0A to 600mA. Both output voltages should be within
±4% tolerance.
5. Set the load current of both outputs to 600mA and the
input voltages to 12V, and then measure each output
ripple voltage (refer to Figure 2 for proper measure-
ment technique); they should each measure less than
20mVAC. Also, observe the voltage waveform at either
switch node (Pin 5 for reg.1 and Pin 8 for reg.2) of each
regulator. The switching frequencies should be about
2.25MHz ±20% (T = 555ns and 370ns). Both switch
node waveforms should be rectangular in shape, and
180° out-of-phase with each other.
6. To operate the ckt.s in Burst Mode operation, change
the shunt position of header JP3 to BURST MODE.
7. Regulators 1 (PVIN1) and 2 (PVIN2) are completely
separated from each other; thus, they can be powered
from different individual input supplies (if R11 is re-
moved), as can the signal input supply, SVIN. However,
SVIN must powered for either regulator to function
(SVIN is connected to PVIN1 through a filter on the
demo board.).
8. When finished, insert shunts XJP1 and XJP2 to the OFF
position(s) and disconnect the power.
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 circuit or even exceed the
maximum voltage rating of the IC. To eliminate the ring-
ing, a small tantalum capacitor (for instance, AVX part #
TPSY226M035R0200) is inserted on the pads between
the input power and return terminals on the bottom of the
demo board. The (greater) ESR of the tantalum capacitor
will dampen the (possible) ringing voltage caused by the
long input leads. On a normal, typical PCB, with short
traces, this capacitor is not needed.
