2
dc1780abfa
DEMO MANUAL DC1780A-B
QUICK START PROCEDURE
Demonstration circuit DC1780A-B is easy to set up to
evaluate the performance of PolyPhase operation of the
LTM4620EV. Due to the high input/output current, select
a proper input supply/load/cable which can sustain the
full load operation. Please refer to Figure 2 for proper
measurement setup and follow the procedure below:
1. Place jumpers in the following positions for a typical
1.0V
OUT
application:
JP1
JP2
JP4-JP8
CLK
RUN
V
OUT
SELECT
INT_CLK
OFF
ON JP4/1.0V
2. With power off, connect the input power supply, load
and meters as shown in Figure 2. Preset the load to 0A
and V
IN
supply to 12V.
3. Turn on the power supply at the input. Place JP2 to
ON position. The output voltage between V
OUT
+
and
V
OUT
–
should be 1.0V ± 1.5% (0.985V to 1.015V).
4. Once the proper output voltage is established, adjust the
load within the operating range and observe the output
voltage regulation, output voltage ripple, efficiency
and other parameters. Output voltage ripple should
be measured at J7 with BNC cables. 50Ω termination
should be set on the oscilloscope or BNC cables.
5. (Optional) For optional load transient test, apply an
adjustable pulse signal between IOSTEP CLK and GND
test point. The pulse amplitude (3V to 3.5V) sets the load
step current amplitude. The output transient current can
be monitored at the BNC connector J8 (5mV/A). The
pulse signal should be very small duty cycle (< 10%)
to limit the thermal stress on the transient load circuit.
6. (Optional) LTM4620 can be synchronized to an external
clock signal. Place the JP1 jumper on EXT_CLK and
apply a clock signal (0V to 5V, square wave) on the
EXT_CLK test point.
PERFORMANCE SUMMARY
Specifications are at T
A
= 25°C
PARAMETER
CONDITIONS/NOTES
VALUE
Input Voltage Range
4.5V to 16V
Output Voltage V
OUT
V
IN
= 4.5V to 16V, I
OUT
= 0A to 75A, JP4: 1.0V
1.0V ± 1.5% (0.985V to 1.015V)
Maximum Continuous Output Current
Derating is necessary for certain V
IN
, V
OUT
and thermal
conditions, see data sheet for detail.
75A
Default Operating Frequency
500kHz
Resistor Programmable Frequency Range
400kHz to 780kHz
External Clock Sync. Frequency Range
400kHz to 780kHz
Efficiency V
IN
= 12V, V
OUT
= 1.0V, I
OUT
= 75A, f
SW
= 500kHz
80.6% See Figure 4
Load Transient
V
IN
= 12V, V
OUT
= 1.0V, I
SETP
= 37.5A to 75A
<163mV, See Figure 5
Output Voltage Ripple
V
IN
= 12V, V
OUT
= 1.0V, I
OUT
= 75A, f
SW
= 500kHz
<10mV, See Figure 6
Table 1. LTM4620 Demo Cards for up to 100A Point-of-Load Regulation
MAXIMUM
OUTPUT CURRENT
NUMBER OF OUTPUT
VOLTAGES
NUMBER OF LTM4620 μMODULE
REGULATORS ON THE BOARD
DEMO CARD NUMBER
13A, 13A
2
1
DC1498A
50A
1
2
DC1780A-A
75A
1
3
DC1780A-B
100A
1
4
DC1780A-C
