Quick Start Procedure - Analog Devices EVAL-LTC3313EV-A-Z User Manual

User Guide

QUICK START PROCEDURE

Before following the quick start procedure, note that for accurate
V , V , and efficiency measurements, measure V
IN OUT
SNSE and GND SNSN turrets and measure V
SNSE and GND SNSE turrets, which are illustrated as VM1 and
VM2 in Figure 6. In addition, when measuring the input or output
ripple, avoid a long ground lead on the oscilloscope probe.
Refer to Figure 6 for the proper measurement equipment test setup
and also take the following steps:
1. Set the JP1 jumper to the HI position.
2. With power off, connect the input power supply to V
If the input EMI filter is desired, connect the input power supply
to V EMI and GND.
IN
3. Set the power supply (PS1) current limit to 10 A.
4. Set the electronic load (LD1) to CC mode and a 0 A current.
5. Slowly increase PS1 to 1.0 V. If the PS1 output current reads
less than 20 mA, increase PS1 to 3.3 V.
6. Verify that VM1 reads 3.3 V and that VM2 reads approximately
1.2 V.
7. Check VM1, VM2, VM3, the PS1 output current, and the LD1
input current.
8. Connect an oscilloscope voltage probe as shown in
Figure 8.
9. Set the channel to AC-coupled, the voltage scale to 20 mV, and
the time base to 10 µs. Also, check the V
that the PGOOD voltage is more than 3 V.
10. Increase the load by 1 A intervals up to 15 A and observe the
voltage output regulation, ripple voltage, and the voltage on the
SSTT turret.
T °C = − 273
V SSTT
11. Use the following equation to calculate the die temperature:
J
4 mV
analog.com
at the VIN
IN
at the VOUT
OUT
and GND.
IN
Figure 7 or
ripple and verify
OUT
(4)
12. If pulse-skipping mode is desired, set PS1 to 0 V, install a 0
Ω resistor in the R3 location, and remove R6. Repeat Step
1 through Step 11. In step 11, observe that the switching
waveform is now in pulse-skipping mode at light load.
13. Optionally, to change the frequency, remove R3 and R4, if
installed. Install the desired RT resistor in the R7 location. Note
that the MODE/SYNC pin must have high impedance to GND
and V . Size the inductor, output capacitors, and compensation
IN
components to provide the desired inductor ripple and a stable
output. Refer to the LTC3313
more information on choosing the required components.
14. To test the transient response with a base load, add the desired
resistor to produce a minimum load between the V
I_STEP turrets (RL shown on
resistance is RL + R14 (20 mΩ). Adjust a signal generator with
a 10 ms period, a 10% duty cycle, and an amplitude from 1 V to
2 V to start.
15. Measure the I_STEP voltage to observe the current, V
mΩ. Adjust the amplitude of the pulse to provide the desired
transient. Connect the signal generator (SG_INPUT) between
the SG_INPUT and GND turrets. Adjust the rising and falling
edge of the pulse to provide the desired ramp rate.
shows a load step from 5 A to 10 A. Refer to the following
I =
equations:
V I_STEP
OUT
20 mΩ
V = V − V
GS SG_INPUT
16. When done, turn off SG_INPUT, PS1, and the load, and remove
all the connections to the EVAL-LTC3313EV-A-Z.
EVAL-LTC3313
data sheet and LTpowerCAD
and the
OUT
Figure 6). Note that the total load
I_STEP
Figure 5
I_STEP
Rev. 0 | 5 of 11
for
/20
(5)
(6)