DUAL SYNCHRONOUS, 600MA, 1.5MHZ STEP-DOWN DC/DC REGULATOR
QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 701
LTC3407
DESCRIPTION
Demonstration circuit 701 is a Dual Synchronous,
600mA, 1.5MHz Step-Down DC/DC Regulator featur-
ing the LTC 3407. The DC701 has an input voltage
range of 2.5V to 5.5V, and either output is capable of
delivering up to 600mA of output current. In Burst
Mode™ operation, the LTC3407 requires only 40 uA
of quiescent current, and the DC701 provides higher
efficiency at light load currents. In Pulse Skip mode,
the DC701 provides lower output ripple voltage at
light load currents. In either mode, the DC701 can
provide up to 96% efficiency on either channel and
consumes less than 1uA in shutdown. The LTC3407
comes in a small 10-Pin DFN package, which has an
exposed pad on the bottom-side of the IC for better
thermal performance. These features, plus the nomi-
nal operating frequency of 1.5MHz (allowing the ex-
clusive use of low profile surface mount compo-
nents), make the DC701 demo board an ideal circuit
for use in battery-powered, hand-held applications.
Design files for this circuit board are available. Call
the LTC factory.
LTC is a trademark of Linear Technology Corporation
Table 1.
Performance Summary (TA = 25°C)
PARAMETER
Minimum Input Voltage
Maximum Input Voltage
Output Voltage VOUT1
Typical Output Ripple VOUT1
Output Regulation
Output Voltage VOUT2
Typical Output Ripple VOUT2
Output Regulation
Nominal Switching Frequency
VIN = 2.5V to 5.5V, IOUT1 = 0A to 600 mA
VIN = 5V, IOUT1 = 600 mA (20 MHz BW)
Line
Load
VIN = 2.5V to 5.5V, IOUT2 = 0A to 600 mA
VIN = 5V, IOUT2 = 600 mA (20 MHz BW)
Line
Load
CONDITION
VALUE
2.5V
5.5V
1.2V ±2%
1.5V ±2%
1.8V ±2%
20mVP–P
±1%
±1%
2.5V ±2%
20mVP–P
±1%
±1%
1.5 MHz
QUICK START PROCEDURE
Demonstration circuit 701 is easy to set up to evalu-
ate the performance of the LTC3407. Refer to Figure 1
for proper measurement equipment setup and follow
the procedure below.
1
DUAL SYNCHRONOUS, 600MA, 1.5MHZ STEP-DOWN DC/DC REGULATOR
Note:
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 out-
put voltage ripple by touching the probe tip directly
across the Vin or Vout and GND terminals. See Figure
2 for proper scope probe technique.
Note:
Capacitor C5 is an optional part. It was in-
serted on the DC701 to dampen the (possible) ringing
voltage due to the use of long input leads. On a nor-
mal, typical PCB, with short traces, the capacitor is
not needed.
1.
QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 701
with roughly 32 uA due to the optional 100 kΩ
pull-up resistor of the Power-On Reset (POR) fea-
ture. This resistor can be removed, and the actual
shutdown supply current (of approx. 1 uA) can be
measured, if the POR feature is not required.
4.
Turn on Vout1 and Vout2 by changing jumpers JP1
and JP2 from the OFF position(s) to the ON posi-
tion(s). Vary the input voltage from 2.5V to 5.5V
and adjust each load current from 0 to 600mA.
Both output voltages should be regulating.
Set the load current of both outputs between 200
mA and 600 mA, and measure both output ripple
voltages; they should measure less than 20 mVAC
each. Also, observe the voltage waveform at the
switch node (pin 3) of each regulator. The switch-
ing frequencies should be between 1.2 MHz and
1.8 MHz (T = 0.833 us and 0.555 us), and each
switch node waveform should be rectangular in
shape.
To change the mode of operation, change jumpers
JP1 and JP2 from the ON position(s) to the OFF
position(s). Then change jumper JP4 to the alter-
native position. Re-insert jumpers JP1 and JP2
into the ON position(s). Observe the voltage wave-
form at both switch nodes.
to the
5.
Connect the input power supply to the Vin and
GND terminals on the left-side of the board. Do
not hot-plug Vin or increase Vin over the rated
maximum supply voltage of 5.5V, or the part may
be damaged. Connect the loads between the Vout
and GND terminals on the right-side of the board.
Refer to Figure 1 for the proper measurement
equipment setup.
Before proceeding to operation, insert jumpers JP1
and JP2 into the OFF positions, jumper JP3 into
the Vout1 voltage position of choice (1.2V, 1.5V,
and 1.8V), and jumper JP4 into the desired mode
of operation: Pulse Skip or Burst Mode.
Apply 3.3V at Vin. Measure both Vouts; they
should read 0V. If desired, one can measure the
shutdown supply current at this point. The supply
current will be approximately 33 uA in shutdown,
6.
2.
3.
When finished, insert jumpers JP1 and JP2
OFF position(s) and disconnect the power.
If more efficiency is desired from the Demo Circuit, replace the stock inductor, a Taiyo Yuden part #
LQLBC2518M2R2M, with a Murata inductor, # LQH32CN2R2M11. Due to its large size, the Murata inductor has
lower DCR than the Taiyo Yuden inductor, thus has less power dissipation.
2
DUAL SYNCHRONOUS, 600MA, 1.5MHZ STEP-DOWN DC/DC REGULATOR
QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 701
Figure 1. Proper Measurement Equipment Setup
Figure 2. Scope Probe Placement for Measuring Input or Output Ripple
3
5
4
3
2
1
* Capacitor C5 is an optional part. It was inserted on the DC701 to dampen the (possible) ringing voltage
due to the use of long input leads. On a normal, typical PCB, with short traces, the capacitor is not
needed.
D
Vin
2.5V-5.5V
3
E1
C5*
+
47uF
10V
(Opt.)
Cin
10uF
6.3V
JP1
CH.1
2
R1
4.7M
5%
U1
LTC3407EDD
Vin
JP2
CH.2
2
R2
100K
R3
4.7M
5%
D
3
On
Off
1
On
Off
1
Gnd
E5
VIN
3
POR
POR
8
E7
C
2
Vout1
1.2V/1.5V/1.8V
@ 600mA
E2
C3
(Opt.)
Cout1
10uF
6.3V
R4
604K
L1
2.2uH
4
C1
10pF
RUN1
C
SW1
RUN2
9
L2
2.2uH
Vout2
2.5V @ 600mA
C2
10pF
R6
887K
Cout2
10uF
6.3V
C4
(Opt.)
E3
SW2
MODE/SYNC
1
FBK1
7
Gnd
E4
R5
604K
R8
402K
R9
301K
GND
GND
11
FBK2
10
R7
280K
Gnd
E6
1.2V
1.5V
1.8V
5
2
4
6
+
+
+
B
+
+
+
JP3
Voltage Select
Vin
R10
4.7M
5%
2
JP4
1
Burst Pulse
Mode Skip
6
B
1
3
5
3
LTC CONFIDENTIAL - FOR CUSTOMER USE ONLY
Customer Notice
A
Linear Technology Has Made A Best Effort To Design A
Circuit That Meets Customer-Supplied Specifications;
However, It Remains The Customer's Responsibility To
Verify Proper And Reliable Operation In The Actual
Application. Component Substitution And Printed
Circuit Board Layout May Significantly Affect Circuit
Performance Or Reliability. Contact Linear Technology
Applications Engineering For Assistance.
This Circuit Is Proprietary To Linear Technology And
Supplied For Use With Linear Technology Parts.
5
4
3
1630 McCARTHY BLVD.
MILPITAS, CA. 95035
408-432-1900
408-434-0507 FAX
Title
LINEAR TECHNOLOGY CORPORATION
A
Dual Synchronous Step-Down DC/DC Converter
Document Number
Size
Date:
Demo Circuit 701A
2
LTC3407EDD
Sheet
1
1
Rev
Monday, November 10, 2003
of
1
Item
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Qty
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0
1
7
3
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3
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1
1
Ref
COUT1,COUT2,CIN
C2,C1
C3,C4 (Optional)
C5
E1,E2,E3,E4,E5,E6,E7
JP1,JP2,JP4
JP3
JP1,JP2,JP3,JP4
L1,L2
R1,R3,R10
R2
R4,R5
R6
R7
R8
R9
U1
Desc
CAP, X5R 10uF 6.3V 20% 0805
CAP, NPO 10pF 50V 10% 0402
CAP, 0805
CAP, TANT 47uF 10V 20% 6032
TURRETS
HEADER, 3PIN 2mm
HEADER, 3X2 2mm
SHUNT,
INDUCTOR, 2.2uH
RES, 4.7M OHMS 5% 1/16W 0402
RES, 100K OHMS 1% 1/16W 0402
RES, 604K OHMS 1% 1/16W 0402
RES, 887K OHMS 1% 1/16W 0402
RES, 280K OHMS 1% 1/16W 0402
RES, 402K OHMS 1% 1/16W 0402
RES, 301K OHMS 1% 1/16W 0402
IC, LTC3407EDD
Part Number
TAIYO YUDEN JMK212BJ106MG
AVX 04025A100KAT
TBD
AVX TAJW476M010R
MILL-MAX 2501-2
COMM CON 2802S-03-G1
COMM CON 2202S-06G1
COMM CON, CCIJ2MM-138G
TAIYO YUDEN LQLBC25182R2M
AAC CR05-475JM
AAC CR05-1003FM
AAC CR05-6043FM
AAC CR05-8873FM
AAC CR05-2803FM
AAC CR05-4023FM
AAC CR05-3013FM
LINEAR TECH. LTC3407EDD
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