Linear Technology LTC3718 Quick Start Manual

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 464
DESCRIPTION
Demonstration circuit 464 is a termination power supply
that sinks or sources up to 12A current. Typical applica-
tions include termination power supplies for DDR or
QDR memories. DC464 utilizes the LTC3718, a constant
on-time, valley current mode synchronous buck control-
ler with an integrated monolithic boost switcher that
produces 5V bias for driving logic level MOSFETs. The
demo circuit provides additional footprints for paralleling
more MOSFETs and input/output capacitors for higher
current applications. The output voltage (V
half of the reference voltage (V
SETUP NOTES
JUMPER SETTINGS
JP1: BOOST at ON position
JP2: VIN2 at ON position
QUICK START PROCEDURE
Refer to Figure 1 and Figure 2 for proper measurement
equipment setup and follow the procedure below:
Connect the input 2.5V power source to the VIN and
1.
GND pins using wires capable of handling 6A current.
Turn on the input power supply. VOUT should read
2.
about V /2±0.05V. If V
IN
=1.25V±0.05V
SOURCING CURRENT TEST (FIGURE 1)
Turn off the input power supply VIN first.
3.
Connect the load to the VOUT and GND pins with the
4.
positive terminal of the load connecting to VOUT.
Turn on VIN.
5.
) equals
OUT
). The default refer-
REF
is fixed at 2.5V, V
IN
DDR, HSTL, STTL TERMINATION POWER SUPPLY
ence voltage is the input voltage, V
ence can be provided to program the output voltage di-
rectly.
SPECIFICATIONS
• V
2.5V typical, 1.5V–5V
IN
• V
V /2
OUT IN
• I ±10A continuous, ±12A
OUT
100LFM
EXTERNAL REFERENCE
The output of this demo board can be programmed by
the external reference at the VREF pin.
R4 must be removed before applying V
NOTE:
Increase the load current to 10A. V
6.
/2 ±0.05V. If V
equal to V
IN
should read about 1.25V±0.05V.
SINKING CURRENT TEST (FIGURE 2)
Turn off the input power supply VIN first.
7.
OUT
Connect the load to the VIN and VOUT pins with the
8.
positive terminal of the load connecting to VIN and
the negative terminal of load connecting to VOUT.
Turn on VIN.
9.
Increase the load current to 10A. If VREF is fixed at
10.
2.5V, VOUT should read about 1.25V±0.05V.
LTC3718
. An external refer-
IN
with air flow at
MAX
.
REF
should always
OUT
is fixed at 2.5V, V
IN OUT
1