LTC3370EUH Datasheet, PDF (3/10 Pages) Linear Technology – 4-Channel 8A Configurable Buck DC/DCs

DEMO MANUAL DC2311A
Quick Start Procedure
The DC2311A is easy to set up to evaluate the performance
of the LTC3370. Refer to Figure 1 and Figure 2 for proper
measurement equipment setup and follow the evaluation
procedure below.
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 Figure 2 for
proper scope probe technique.
1. Set the JP1 – JP4 jumpers on the DC2311A board to
the ON position.
2. Set the JP5 jumper on the DC2311A board to the
BURST position.
3. Set the JP6 jumper on the DC2311A board to the V_CC
position.
4. With power off, connect a 0V to 6V, 50mA power sup-
ply (PS5) to V_CC input terminal and GND with a series
ammeter and a voltmeter as shown in Figure 1.
5. Turn on and set the PS5 to a desired input voltage
between 2.7V and 5.5V.
6. With a digital volt meter, measure the voltage on the
temp pin. This represents the die temperature,
(V_TEMP – 45mV)/7mV = °C. 220mV = 25°C
7. With power off, connect 0V to 6V, 2A power supplies
to each input pair (PS1-PS4), V_INAB, V_INC/V_IND, V_INE/
V_INF, V_ING/V_INH and GND with a series ammeter and
a voltmeter as shown in Figure 1. A single 0V to 6V,
10A supply can be used instead to supply all V_IN inputs
and the V_CC input simultaneously.
8. Turn on and set the PS1 input power supply to 5.0V
and observe that V_OUT1 regulates to 1.2V.
NOTE. Make sure that the input voltage does not exceed 6V.
9. With power off, connect a 0A to 2A load to V_OUT1 and
GND with a series ammeter and a voltmeter as shown
in Figure 1.
10. Slowly increase the load from 0A to 2A and observe the
output voltage. The output ripple may also be observed
using an oscilloscope with the probe connected as
shown in Figure 2.
11. Set Load1 to 100mA.
12. Repeat steps 8 to 11 for each output using their
respective power supplies and loads. Each output
voltage should regulate to the voltage indicated on
the silkscreen of the DC2311A.
13. Momentarily short V_OUT1 to ground with a clip lead and
observe that the PGOODALL LED, D1, on the demo
board illuminates. The LED shuts off when the short
is removed.
14. With Load1 set to 100mA, observe the burst mode
ripple on V_OUT1.
15. Set the JP5 jumper on the DC2311A board to the
FORCED CONT position and observe the forced con-
tinuous mode ripple on V_OUT1.
16. With an oscilloscope using two probes each set to
1V/Div vertical scale and 1µs/Div horizontal scale,
compare the phase between SWAB to SWCD, SWEF,
and then SWGH. Observe that the switch nodes are
90°, 270°, and 180° out of phase respectively with
SWAB.
17. Set the JP5 jumper on the DC2311A board to the PLL
position.
18. Set a pulse generator to output a 0V to 5V pulse at
2MHz, 50% Duty cycle and connect it to the PLL/MODE
terminal and GND.
19. Change the frequency of the pulse generator from
2MHz to 3MHz and observe how the frequency of
SWAB follows the pulse generator.
20. Set LOAD1 greater than 1.0A. With an oscilloscope
probe on SWAB, remove the pulse signal to the PLL/
MODE terminal and observe how the switch frequency
settles from 3MHz back to 2MHz.
21. Refer to the LTC3370 data sheet for more details on
how the LTC3370 operates.
22. When done, turn off all loads and power supplies.
dc2311af
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