QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 802
LTC3828 DUAL 2-PHASE STEP DOWN CONVERTER WITH TRACKING
1
LTC3828EUH
DESCRIPTION
Demonstration circuit 802 features the dual-output,
2-phase synchronous buck regulator LTC3828EUH.
The input voltage range of the demo board is 7V to
21V. The outputs are 5V/5A
MAX
and 3.3V/5A
MAX
. De-
pending on the setting of the optional resistors and
jumpers, each output can track an external ramp
voltage during start up or one output can track an-
other output on the same board during start up. At
light load, the supplies can operate in high efficiency
mode or low output ripple mode depending on
jumper selection.
The switching frequency is a jumper-selectable
250kHz or 550kHz, or one resistor can set the fre-
quency anywhere in between. The supply can also be
synchronized by an external clock signal. A
CLOCKOUT pin provides an output clock signal to
synchronize other supplies if needed. The
LTC3828EUH regulator IC is in a small 5 mm x 5 mm
package with exposed thermal pad for low thermal
impedance.
Design files for this circuit board are available.
Call the LTC factory.
,
LTC and LT are registered trademarks of Linear Technology Corporation.
Table 1.
Performance Summary (T
A
= 25°C)
PARAMETER
CONDITION
VALUE
Input Voltage
7V-21V
Output Voltage V
OUT1
I
OUT1
= 0A to 5A
5V ± 2%
Output Voltage V
OUT2
I
OUT2
= 0A to 5A
3.3V ± 2%
Maximum Output Current
VIN = 7V-21V
5A Each Output
Switching frequency
FCB = CCM
Jumper selectable
250kHz or 550kHz
Full Load Efficiency
V
IN
= 12V, V
OUT1
= 5V, I
OUT1
= 5A, fsw=550kHz
93% Typical
V
IN
= 12V, V
OUT2
= 3.3V, I
OUT2
= 5A, fsw=550kHz
91% Typical
QUICK START PROCEDURE
Demonstration circuit 802 is easy to set up to evalu-
ate the performance of the LTC3828EUH. Refer to
Figure 1 for proper measurement equipment setup
and follow the 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 out-
put voltage ripple by touching the probe tip directly