2
dc2455abf
DEMO MANUAL DC2455A-B
Quick start proceDure
Demonstration circuit DC2455A-B is easy to set up to
evaluate the performance of PolyPhase operation of the
LTM4650EY-1. Due to the high input/output current, user
should select the proper input supply/load/cable which
can sustain the full load operation. It’s recommended to
pull load current from J2 and J4. The load current pulled
from J5 and J6 shouldn’t exceed 25A. 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
OFF
ON JP5 / 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
O
+
” and “V
O
–
”
should be 1.0V ± 1.5% (0.985V~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 J11 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. Pulse amplitude (3V~3.5V) sets the
load step current amplitude. The output transient current
can be monitored at the BNC connector J12 (5mV/A).
The pulse signal should be very small duty cycle (<
10%) to limit the thermal stress on the transient load
circuit.
6. (Optional) LTM4650-1 can be synchronized to an exter-
nal clock signal. Place the JP1 jumper on EXT and apply
a clock signal (0~5V, square wave) on the “EXT_CLK”
test point.
7. (Optional) The outputs of LTM4650-1 can track another
supply. The output voltage tracks the voltage on TRACK
when a valid signal is applied on the test point.
8. (Optional) DC2455A-B can be configured to a dual
outputs configuration with V
O
at 125A load current
and V
O2
at 25A load current. Stuff 0Ω resistor on R61
and 0.1µF on C14. Remove R22, R23, R24, R26, R27,
R28, R32, R33, R35. Output voltage V
O2
is set by R37
based on the equation V
O2
= 0.6V(1 + 60.4k/R37).
performance summary
Specifications are at T
A
= 25°C
PARAMETER
CONDITIONS / NOTES
VALUE
Input Voltage Range
4.5V ~ 15V
Output Voltage V
OUT
V
IN
= 4.5V to 15V, I
OUT
= 0A to 150A, JP5: 1.0V
1.0V ± 1.5% (0.985V ~ 1.015V)
Maximum Continuous Output Current
De-rating is necessary for certain V
IN
, V
OUT
and thermal
conditions, see data sheet for detail.
150A
Default Operating Frequency
500kHz
Resistor Programmable Frequency Range
400kHz – 780kHz
External Clock Sync. Frequency Range
400kHz – 780kHz
Efficiency
V
IN
= 12V, V
OUT
= 1.0V, I
OUT
= 150A, f
SW
= 500kHz
86.1% See Figure 3
Load Transient
V
IN
= 12V, V
OUT
= 1.0V, I
STEP
= 72A to 112.5A
< 53mV, See Figure 4
