QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 389
HIGH EFFICIENCY NOTEBOOK CPU POWER SUPPLY
1
LTC3778
DESCRIPTION
Demonstration circuit 389 is a step down controller
featuring the LTC3778. It produces an output voltage
suitable for Intel Mobile Tualatin, Low Voltage Tualatin
and Ultra Low Voltage mobile processors. The
LTC3778 is a synchronous step-down controller. It
uses valley current control architecture to deliver low
duty cycles.
The maximum current supported by each version of
the DC389 conforms to Intel IMVP-II Mobile Proces-
sor Core Voltage Design Guide REF. NO. OR-2980.
Please contact Intel to obtain this restricted docu-
ment. DC389 includes a dynamic load circuit for the
convenience of the user.
There are three versions of the board:
• 389A-A: Mobile Tualatin, 23A max output
• 389A-B: Low Voltage Tualatin, 15A max
• 389A-C: Ultra Low Voltage Tualatin, 13A max
Design files for this circuit board are available. Call
the LTC factory.
Table 1.
Performance Summary
PARAMETER CONDITION VALUE
Minimum Input Voltage 7.5V
Maximum Input Voltage 24
V
OUT ,
I
OUT
See Tables 2,3,4
Typical Output Ripple V
OUT
V
IN
= 12V, I
OUT
=15A 20mV
P–P
Nominal Switching Frequency 300kHz
QUICK START PROCEDURE
Demonstration circuit 389 is easy to set up to evalu-
ate the performance of the LTC3778. Refer to Figure 1
for proper measurement equipment setup and follow
the procedure below:
Table 2.
Jumper Descriptions (See Figure 1)
JUMPER
DESCRIPTION
JUMPER POSITION
PURPOSE
NUM
BER
1-2 2-3
Dynamic
Load
JP1 Disabled Enabled
VRON JP2 Enabled Disabled
Deep Sleep JP3 Disabled Enabled
Deeper
Sleep
JP4 Enabled Disabled
Perform-
ance Mode
JP5
Performance Opti-
mized Mode
Battery Opti-
mized Mode
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 output volt-
age ripple by touching the probe tip directly across
the input or output and ground terminals. See Figure
2 for proper scope probe technique.
1.
Set jumpers as shown in Figure 1. See also Table 2
for jumper descriptions.
2.
With power off, connect the input power supply to
VIN and GND.
3.
Turn on the power in this sequence:
a. VIN (Do not exceed 24V)
b. 3.3V
c. 5V (Do not allow 5V to be ON without VIN ON)
d. ±12V.
