QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 389
HIGH EFFICIENCY NOTEBOOK CPU POWER SUPPLY
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-
Table 1. Performance Summary
PARAMETER
Minimum Input Voltage
Maximum Input Voltage
V
OUT ,
I
OUT
Typical Output Ripple V
OUT
Nominal Switching Frequency
V
IN
= 12V, I
OUT
=15A
CONDITION
VALUE
7.5V
24
See Tables 2,3,4
20mV
P–P
300kHz
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.
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
PURPOSE
Dynamic
Load
VRON
Deep Sleep
Deeper
Sleep
Perform-
ance Mode
NUM
BER
JP1
JP2
JP3
JP4
JP5
JUMPER POSITION
1-2
Disabled
Enabled
Disabled
Enabled
Performance Opti-
mized Mode
2-3
Enabled
Disabled
Enabled
Disabled
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.
b.
c.
d.
VIN
(Do not exceed 24V)
3.3V
5V
(Do not allow 5V to be ON without VIN ON)
±12V.
1
QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 389
HIGH EFFICIENCY NOTEBOOK CPU POWER SUPPLY
4.
Check for the proper output voltages. See Tables 3
5.
Once the proper output voltage is established, ad-
to 5 for expected output voltages.
If there is no output, temporarily disconnect the
load to make sure that the load is not set too high.
just the load within the operating range and ob-
serve the output voltage regulation, ripple voltage,
efficiency and other parameters.
See Figures 3 to 5 for expected performance.
–
+
–
+
JUMPER
POSITIONS
3
2
1
+
+
–
–
VIN
GND
Figure 1. Proper Measurement Equipment Setup
–
SCOPE OR
VOLTMETER
+
–
+
–
+
+
–
+
–
+
LOAD
–
Figure 2. Measuring Input or Out-
put Ripple
2
QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 389
HIGH EFFICIENCY NOTEBOOK CPU POWER SUPPLY
100
90
80
EFFICIENCY (%)
70
60
50
40
30
20
10
0
0
5
10
15
20
25
389A-A
389A-B
389A-C
20mV/DIV
10µs/DIV
2µs/DIV
LOAD CURRENT (A)
Figure 3. Step Load Response
(389A-A, Performance Optimized
Mode, V
IN
= 15V)
Table 3. Version A for Mobile Tualatin CPU
MODE
BOM*
POM**
POM**
DEEP
SLP
BOM*
DEEP
SLP
DEEPER
SLP
JP2
1–2
1–2
JP3
1–2
1–2
JP4
2–3
2–3
JP5
2–3
1–2
0A
1.115–
1.155
1.380–
1.420
1.318–
1.358
1.064–
1.104
0 .810–
0.870
Figure 4. Typical Output Ripple
(389A-A, Performance Optimized
Mode, I
OUT
= 15A, V
IN
= 15V)
Figure 5. Typical Performance Mode
Efficiency curves for the 389A-A,
389A-B and 389A-C
3A
6A
8A
14A
1.059–
1.099
23A
1.288 –
1.328
1.286–
1.326
1.040–
1.080
0 .810 –
0.870
1–2
2–3
2–3
1–2
1–2
2–3
2–3
2–3
1–2
2–3
1–2
2–3
*Battery Optimized Mode
**Performance Optimized Mode
3
QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 389
HIGH EFFICIENCY NOTEBOOK CPU POWER SUPPLY
Table 4. Version B for Low Voltage Tualatin CPU
MODE
BOM*
POM**
POM**
DEEP
SLP
BOM*
DEEP
SLP
DEEPER
SLP
JP2
1–2
1–2
JP3
1–2
1–2
JP4
2–3
2–3
JP5
2–3
1–2
0A
1.016–
1.056
1.130 –
1.170
1.094–
1.134
0.996 –
1.036
0 .810–
0.870
0.810–
0.870
0.976–
1.016
1.070–
1.110
3A
5A
6A
10A
0.976–
1.016
1.070 –
1.110
15A
1–2
2–3
2–3
1–2
1–2
2–3
2–3
2–3
1–2
2–3
1–2
2–3
*Battery Optimized Mode
**Performance Optimized Mode
Table 5. Version C for Ultra Low Voltage Tualatin CPU
MODE
BOM*
POM**
POM**
DEEP
SLP
BOM*
DEEP
SLP
DEEPER
SLP
JP2
1–2
1–2
JP3
1–2
1–2
JP4
2–3
2–3
JP5
2–3
1–2
0A
0.918–
0.958
1.080–
1.120
1.048–
1.088
0.902–
0.942
0 .810–
0.870
0.810–
0.870
0.886–
0.926
1.028–
1.068
3A
4A
5A
8A
0.886–
0.926
1.028–
1.068
13A
1–2
2–3
2–3
1–2
1–2
2–3
2–3
2–3
1–2
2–3
1–2
2–3
*Battery Optimized Mode
**Performance Optimized Mode
4
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