Linear Technology DEMO CIRCUIT 1672A, Quick Start Manual

1 

DESCRIPTION 

Demonstration circuit 1672A is a high efficiency, 
single phase, synchronous buck converter for Intel 
IMVP-6/IMVP-6.5 CPUs.  It can supply 25A maxi-
mum load current at up to 1.5V output with 4.5V to 
28V input range. The demo board features the 
LTC®3816EUHF controller.  The LTC3816 is a sin-
gle-phase synchronous buck controller in a con-
stant-frequency voltage mode architecture.  The con-
troller’s leading edge modulation topology allows 
extremely low output voltages and supports a phase-
lockable switching frequency up to 550kHz.  The 
output voltage is programmed using a 7-bit VID 
code.  The default VID jumpers (VID6 to VID0) are 
set to be 0110000 for 0.9V output.  The LTC3816 
features all of the IMVP-6/IMVP-6.5 requirements, 
including start-up to a preset boot voltage, differen-
tial remote output voltage sensing with programma-
ble active voltage positioning, Imon output current 
reporting, power optimization during sleep state, and 
slow slew rate sleep state exit.  Fault protection fea-
tures include input undervoltage lockout, cycle-by-
cycle current limit, output overvoltage protection, 
and power-good (PWRGD) and overtemperature 
flags.  The LTC3816 supports wide input range (4.5V 
to 36V) with optional line feedforward compensation, 
temperature compensated inductor DCR or sense 
resistor output current monitoring.  The LTC3816 
can provide high efficiency, high power density and 

versatile power solutions for embedded computing, 
mobile computers, internet devices and navigation 
displays.  The controller is available in 38-pin ther-
mally enhanced eTSSOP and 5mm × 7mm QFN 
packages. 
 
The VRON pin (JP15) provides enable feature. To 
shut down the converter, one simple way is to force 
the VRON pin below 0.65V (JP15: OFF). Use JP19 
jumper to select pulse-skipping or forced continuous 
mode operation.   Switching frequency is pre-set at 
about 400KHz, and it can be easily modified from 
150KHz to 550KHz.  JP20~JP26 (VID0~VID7) are 
used to set the output voltage based on the IMVP-
6/IMVP-6.5 VID code, as shown in table 2.  JP1 and 
JP18 are used to select either IMVP6 or IMVP6.5 
specification.  For detailed information, please see 
LTC3816 data sheet and Intel IMVP-6/IMVP-6.5 spe-
cification. 

 
Design files for this circuit board are available. Call 
the LTC factory. 
 

DEMO CIRCUIT 1672A

QUICK START GUIDE

LTC3816EUHF

HIGH EFFICIENCY SINGLE PHASE BUCK CONVERTER

FOR INTEL IMVP-6/IMVP-6.5 CPUs

Table 1.  

Performance Summary (T

A

 = 25°C) 

PARAMETER CONDITION 

VALUE 

Input Voltage Range 

4.5V to 28V 

Output Voltage, V

OUT

V

IN

 = 4.5-28V, I

OUT

= 0A to 23A, VID6-0=0110000

0.9V ±1.5% 

Maximum Output Current, I

OUT

V

IN

 = 4.5-28V, V

OUTMAX

= 1.5V

25A 

Typical Efficiency 

V

IN

 = 12V, V

OUT

= 1.5V, I

OUT

= 23A 

86.7% 

Typical Switching Frequency 

400kHz