1
dc1700af
DEMO MANUAL DC1700A
DESCRIPTION
LTC3613EWKH
Fast, High Efficiency
Step-Down Regulator
Demonstration circuit 1700A is a fast, high efficiency
synchronous buck DC/DC converter with 4.5V to 24V
input range. It can supply 15A maximum load current at
1.5V output. The demo board features the LTC
®
3613EWKH
regulator. No external MOSFETs are required. The con-
trolled on-time constant frequency valley current mode
architecture allows for both fast transient response and
constant frequency switching in steady-state operation.
Differential output voltage sensing along with a precision
internal reference combine to offer an accurate output
regulation. The LTC3613 is ideal for applications such
as distributed power systems, servers and point-of-load
converters. The LTC3613EWKH is in a 7mm
×
9mm 54-pin
QFN package.
L
, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
PERFORMANCE SUMMARY
The light load operation mode of the converter is de-
termined with the MODE/PLLIN pin. Use JP2 jumper to
select discontinuous mode (DCM) or forced continuous
mode (CCM) operation. Switching frequency is pre-set
at about 350kHz. This frequency can be modified from
200kHz to 1MHz by changing the value of a resistor (R18).
The converter can also be externally synchronized from
200kHz to 1MHz through the MODE/PLLIN pin (PLLIN
terminal on the board). To shut down the converter, one
simple way is to force the RUN pin below 1.1V (JP1: OFF).
The power good output (PGOOD terminal) is low when the
output voltage is outside of the ±7.5% regulation window.
Design files for this circuit board are available at
http://www.linear.com/demo
(T
A
= 25°C)
PARAMETER
CONDITIONS
VALUE
Input Voltage Range
4.5V to 24V
Output Voltage, V
OUT
V
IN
= 4.5V to 24V, I
OUT
= 0A to 15A
1.5V ±2%
Maximum Output Current, I
OUT
V
IN
= 4.5V to 24V, V
OUT
= 1.5V
15A
Typical Output Ripple
V
IN
= 12V, I
OUT
= 15A (20MHz BW)
40mV
P–P
Typical Efficiency
V
IN
= 12V, V
OUT
= 1.5V, I
OUT
= 15A
87.5%
Typical Switching Frequency
350kHz