DEMO MANUAL
DC1185B-A/-B
LTC3850EUF
Dual Phase/Dual Output
Synchronous Buck Converter
DESCRIPTION
Demonstration circuit 1185 is a dual phase/dual output
synchronous buck converter featuring the LTC3850EUF.
The demo board comes in two versions. The output voltages for version DC1185B-A are 2.0V/10A and 1.8V/10A.
The output voltages for version DC1185B-B are 1.5V/15A
and 1.2V/15A. The input voltage range is 6.5V to 14V for
both versions. For applications that have a 5V ±0.5V input,
the board has an optional resistor to tie the INTVCC pin
to the VIN pin.
The demo board uses a high density, 2-sided drop-in layout.
The power components excluding the bulk output and input
capacitors, fit within a 1.35" × 0.75" area on the top layer.
The control circuit resides in a 0.60" × 0.75" area on the
bottom layer. The package style for the LTC3850EUF is a
4mm × 4mm 28-lead QFN with an exposed ground pad.
PERFORMANCE SUMMARY
PARAMETER
The main features of the board include an internal 5V linear
regulator for bias, RUN pins for each output, an EXTVCC
pin and a PGOOD signal. The board can be configured
for either CCM (original setting), Burst Mode®, or pulseskipping operation with the MODE jumper. The board
also has optional resistors for single output/dual phase
operation, rail tracking, DCR sensing and synchronization
to an external clock.
Design files for this circuit board are available at
http://www.linear.com/demo
L, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks
of Linear Technology Corporation. All other trademarks are the property of their respective
owners.
Note: Q1-Q4 MOSFETs changed on September 10, 2013.
See Schematic Diagram.
Specifications are at TA = 25°C
CONDITION
VALUE
Minimum Input Voltage
6.5V
Maximum Input Voltage
14V
Version DC1185B-A
Output Voltage VOUT1
IOUT1 = 0A to 10A
2.0V ±2%
Output Voltage VOUT2
IOUT2 = 0A to 10A
1.8V ±2%
Nominal Switching Frequency
500kHz
VOUT1 = 2.0V, IOUT1 = 10A, VIN = 12V
VOUT2 = 1.8V, IOUT2 = 10A, VIN = 12V
90.2%
89.5%
Output Voltage VOUT1
IOUT1 = 0A to 15A
1.5V ±2%
Output Voltage VOUT2
IOUT2 = 0A to 15A
1.2V ±2%
Full-Load Efficiency
(See Figure 3 for Efficiency Curves)
Version DC1185B-B
Nominal Switching Frequency
Full-Load Efficiency
(See Figure 4 for Efficiency Curves)
400kHz
VOUT1 = 1.5V, IOUT1 = 15A, VIN = 12V
VOUT2 = 1.2V, IOUT2 = 15A, VIN = 12V
88.1%
86.5%
dc1185b-a/-bf
1
DEMO MANUAL
DC1185B-A/-B
QUICK START PROCEDURE
Demonstration circuit 1185 is easy to set up to evaluate
the performance of the LTC3850EUF. Refer to Figure 1
for the proper measurement equipment setup and follow
the procedure below:
Note: When measuring the output or input voltage ripple,
care must be taken to avoid a long ground lead on the
oscilloscope probe. See Figure 2 for the proper scope
probe technique. Short, stiff leads need to be soldered
to the (+) and (–) terminals of an output capacitor. The
probe’s ground ring needs to touch the (–) lead and the
probe tip needs to touch the (+) lead.
Place jumpers in the following positions:
JP1
RUN1
ON
JP2 RUN2
ON
JP3
MODE
CCM
With power off, connect the input power supply to VIN
and GND.
Note: Make sure that the input voltage does not exceed 15V.
Check for the proper output voltages.
Version DC1158B-A:
VOUT1 = 1.960V to 2.040V
VOUT2 = 1.764V to 1.836V
Version DC1158B-B:
VOUT1 = 1.470V to 1.530V
VOUT2 = 1.176V to 1.224V
Once the proper output voltages are established, adjust
the loads within the operating range and observe the
output voltage regulation, ripple voltage, efficiency and
other parameters.
Note: Do not apply load across the VOSn+ and VOSn–
turrets. These turrets are only intended to Kelvin sense
the output voltage across COUT1 and COUT4. Heavy load
currents may damage the output voltage sense traces.
Turn on the power at the input.
Figure 1. Proper Measurement Equipment Setup
dc1185b-a/-bf
2
DEMO MANUAL
DC1185B-A/-B
QUICK START PROCEDURE
+
COUT
VOUT
-
GND
Figure 2. Measuring Output Voltage Ripple
2.0V/10A and 1.8V/10A Efficiency at VIN = 12V and fSW = 500kHz
1.5V/15A and 1.2V/15A Efficiency at VIN = 12V and fSW = 400kHz
95
95
2.0V
90
1.8V
EFFICIENCY (%)
EFFICIENCY (%)
90
85
80
QTOP: RJK030DPB
QBOTTOM: RJK0330DPB
L: TOKO FDU0650-R56M = P3
0.56µH, DCR = 2.45mΩ, 3.2mΩ MAX
RSENSE = 3mΩ
75
70
0
2
4
6
8
LOAD CURRENT (A)
10
1.5V
1.2V
85
80
QTOP: RJK030DPB
QBOTTOM: RJK0330DPB
L: VITEC 59PR9875
0.4µH, DCR = 0.47mΩ ±10%
RSENSE = 2mΩ
75
70
12
Figure 3. Efficiency Curves for the DC1185B-A
0
3
6
9
12
LOAD CURRENT (A)
15
18
Figure 4. Efficiency Curves for the DC1185B-B
SINGLE OUTPUT/DUAL PHASE OPERATION
A single output/dual phase converter may be preferred
for high output current applications. The benefits of
single output/dual phase operation is lower ripple current
through the input and output capacitors, improved load
step response and simplified thermal design. To implement
single output/dual phase operation, make the following
modifications:
1.Tie VOUT1 to VOUT2 by tying together the exposed
copper pads near J3 and J5 at the edge of the board.
Use a piece of heavy copper foil.
2.Tie ITH1 to ITH2 by stuffing 0Ω at R49.
3.Tie VFB1 to VFB2 by stuffing 0Ω at R50.
4.Tie TRK/SS1 to TRK/SS2 by stuffing 0Ω at R52.
5.Tie RUN1 to RUN2 by stuffing 0Ω at R55.
6.Remove the redundant ITH compensation network and
VFB divider.
dc1185b-a/-bf
3
DEMO MANUAL
DC1185B-A/-B
RAIL TRACKING
Demonstration circuit 1185 is set up for independent
turn-on of VOUT1 and VOUT2. The ramp-rate for VOUT1 is
determined by the TRK/SS1 capacitor at C2 and the ramprate for VOUT2 is determined by the TRK/SS2 capacitor
at C47. The turn-on of one rail will not affect the other for
the original demo board.
This board can be modified on the bench to allow VOUT1
to track an external signal. It can also be modified to
allow VOUT2 to track VOUT1 or to allow VOUT2 to track
an external signal. Tables 2 and 3 cover the rail tracking
options for each rail, with the DC3850B-B version used
as an example.
Table 1. VOUT1 Tracking Options for a 1.5V Output
TRACK 1 DIVIDER
TRK/SS1 CAPACITOR
CONFIGURATION
R3
R2
C2
Soft-Start without Tracking (Original Board)
0Ω
Not Stuffed
0.1µF
17.8kΩ
20.0kΩ
Not Stuffed
External Coincident Tracking
Table 2. VOUT2 Tracking Options for a 1.2V Output
TRACK 2 DIVIDER
TRK/SS2 CAPACITOR
CONFIGURATION
R36
R34
R37
C47
Soft-Start without Tracking (Original Board)
0Ω
Not Stuffed
Not Stuffed
0.1µF
Coincident Tracking to VOUT1 (1.5V)
0Ω
10.0kΩ
20.0kΩ
Not Stuffed
10.0kΩ
Not Stuffed
20.0kΩ
Not Stuffed
External Coincident Tracking
dc1185b-a/-bf
4
DEMO MANUAL
DC1185B-A/-B
INDUCTOR DCR SENSING
Demonstration circuit 1185 provides an optional circuit
for DCR sensing. DCR sensing uses the DCR of the inductor to sense the inductor current instead of discrete
sense resistors. The advantages of DCR sensing are lower
cost, reduced board space and higher efficiency, but the
disadvantage is a less accurate current limit. If DCR sensing is used, be sure to select an inductor current with a
sufficiently high saturation current or use an iron powder
type. Tables 3 and 4 show an example of how to modify
the DC1185 for DCR sensing using these parameters:
VOUT1 = 2.0V/10A
VOUT2 = 1.8V/10A
VIN = 6.5V to 14V
fSW = 500kHz, typical
L1, L2 = Toko FDU0650-R56M=P3
(0.56µH, DCR = 2.45mΩ Typ, 3.2mΩ Max)
ILIM = Floating (R42, R44 = Open)
Table 3. VOUT1 Configured as a 2.0V/10A Converter Using DCR Sensing and Discrete Sense Resistors
RSENSE FILTER
RESISTORS
SENSE FIILTER
CAPACITOR
R29, R30
DCR FILTER/DIVIDER RESISTORS
TOP
BOTTOM
SENSE1– TO L1–
JUMPER
C14
R45
R47
R61
CONFIGURATION
RS1
L1
DCR Sensing
Short with Cu
Strip or Very
Short and Thick
Piece of Wire
Toko
FDU0650-R56M=P3
Open
0.1µF
2.37kΩ
6.49kΩ
0Ω
Discrete RSENSE
(Original Board)
3mΩ
2010 Package
Toko
FDU0650-R56M=P3
100Ω
1nF
Open
Open
Open
Table 4. VOUT2 Configured as a 1.8V/10A Converter Using DCR Sensing and Discrete Sense Resistors
RSENSE FILTER
RESISTORS
SENSE FIILTER
CAPACITOR
R39, R40
DCR FILTER/DIVIDER RESISTORS
TOP
BOTTOM
SENSE1– TO L1–
JUMPER
C15
R51
R53
R62
CONFIGURATION
RS2
L2
DCR Sensing
Short with Cu
Strip or Very
Short and Thick
Piece of Wire
Toko
FDU0650-R56M=P3
Open
0.1µF
2.37kΩ
6.49kΩ
0Ω
Discrete RSENSE
(Original Board)
3mΩ
2010 Package
Toko
FDU0650-R56M=P3
100Ω
1nF
Open
Open
Open
dc1185b-a/-bf
5
DEMO MANUAL
DC1185B-A/-B
SYNCHRONIZATION TO AN EXTERNAL CLOCK
The LTC3850 uses a phase-lock-loop which forces its
internal clock to be synchronized to an external clock.
Once synchronized, the rising edge of the top FET gate is
aligned to the rising edge of the external clock. The external
clock signal needs to be applied to the LTC3850’s MODE
pin which is tied to the turret labeled SYNC. The internal
phase lock loop is stabilized by a network on the FREQ pin
of the LTC3850. To set up the DC1185 for synchronization
to an external clock, follow the steps below.
1.Remove R7.
2.Stuff 10kΩ at R8.
3.Stuff 10nF at R10.
4.Leave 1nF at C12.
5.Float the MODE pin by placing the MODE jumper in the
BM position.
6.Apply the external clock from the turret la-beled SYNC
to GND.
dc1185b-a/-bf
6
DEMO MANUAL
DC1185B-A/-B
PARTS LIST
ITEM
QTY
(DC1185B-A)
REFERENCE
PART DESCRIPTION
MANUFACTURER/PART NUMBER
Required Circuit Components
1
3
C11, C32, C36
CAP, 0805 4.7µF 10% 6.3V X5R
AVX 08056D475KAT
2
5
C12, C14, C15, C41, C44
CAP, 0603 1nF 10% 50V X7R
AVX 06035C102KAT
3
5
C2, C17, C20, C21, C47
CAP, 0603 0.1µF 10% 25V X7R
TDK C1608X7R1E104K
4
2
C43, C42
CAP, 0603 100pF 5% 25V X7R
AVX 06033C101JAT
5
1
CIN1
CAP, 180µF 20% 16V OSCON
SANYO OSCON 16SVP180MX
6
2
CIN2, CIN3
CAP, 1210 10µF 10% 16V X5R
TAIYO YUDEN EMK325BJ106KN-T
7
2
COUT1, COUT4
CAP, 1210 47µF 20% 6.3V X5R
TDK C3225X5R0J476MT
8
4
COUT2, COUT3, COUT5, COUT6
CAP, 7343 330µF 20% 2.5V POSCAP
SANYO 2R5TPE330M9
9
2
D2, D1
DIODE, CMDSH-3 SOD323
CENTRAL CMDSH-3TR
10
2
L1, L2
IND, 0.56µH
TOKO FDU0650-R56M=P3
11
2
Q1, Q3
XSTR, N-CHANNEL MOSFET
RENESAS RJK0305DPB
12
2
Q2, Q4
XSTR, N-CHANNEL MOSFET
RENESAS RJK0330DPB
13
1
R10
RES, 0603 3.16k 1% 1/10W
VISHAY CRCW06033K16FKEA
14
1
R18
RES, 0603 2.2Ω 5% 1/10W
VISHAY CRCW06032R20JNEA
15
1
R27
RES, 0603 30.1k 1% 1/10W
VISHAY CRCW060330K1FKEA
16
4
R29, R30, R39, R40
RES, 0603 100Ω 5% 1/10W
VISHAY CRCW0603100RJNEA
17
2
R31,R35
RES, 0603 8.66k 1% 1/10W
VISHAY CRCW06038K66FKEA
18
2
R32,R33
RES, 0603 20k 1% 1/10W
VISHAY CRCW060320KFKEA
19
1
R43
RES, 0603 25.5k 1% 1/10W
VISHAY CRCW060325K5FKEA
20
1
R46
RES, 0603 100k 5% 1/10W
VISHAY CRCW0603100KJNEB
21
2
R7, R4
RES, 0603 10k 1% 1/16W
VISHAY CRCW060310K0FKEB
22
3
R8, R9, R25
RES, 0603 0Ω JUMPER
PANASONIC ERJ3GEY0R00V
23
2
RS2, RS1
RES, 2010 0.003Ω 5% 1/2W
VISHAY WSL20103L000FEA
24
1
U1
IC, LTC3850EUF
LINEAR TECH. LTC3850EUF
Additional Circuit Components
1
0
CIN5, CIN4
CAP, 1210 OPTION
OPTION
2
0
C1, C37, C38, C47, C48, C49
CAP, 0603 OPTION
OPTION
3
1
C50
CAP, 0603 1µF 20% 16V X7R
AVX 0603YC105MAT2A
4
0
D4, D3
DIODE, SCHOTTKY 40V 3A OPTION
OPTION
5
0
Q5, Q6, Q7, Q8
DO NOT STUFF
OPTION
6
3
R1, R3, R36
RES, 0603 0Ω JUMPER
PANASONIC ERJ3GEY0R00V
7
0
R2, R26, R28, R34, R37, R38, R41, R42,
R44, R45, R47, R49, R50-R53, R55,
R60-R62
RES, 0603 OPTION
OPTION
1
12
E1-E6, E9-E14
TURRET
MILL-MAX 2501-2-00-80-00-00-07-0
2
2
JP2, JP1
HEADER, 3-PIN, 2mm
SAMTEC TMM-103-02-L-S
3
1
JP3
HEADER, 4-PIN
SAMTEC TMM-104-02-L-S
4
6
J1, J2, J3, J4, J5, J6
JACK, BANANA
KEYSTONE 575-4
5
3
JP1-JP3
SHUNT, 2mm
SAMTEC 2SN-BK-G
Hardware
dc1185b-a/-bf
7
DEMO MANUAL
DC1185B-A/-B
PARTS LIST
ITEM
QTY
(DC1185B-B)
REFERENCE
PART DESCRIPTION
MANUFACTURER/PART NUMBER
Required Circuit Components
1
3
C11, C32, C36
CAP, 0805 4.7µF 10% 6.3V X5R
AVX 08056D475KAT
2
5
C12, C14, C15, C41, C44
CAP, 0603 1nF 10% 50V X7R
AVX 06035C102KAT
3
5
C2, C17, C20, C21, C47
CAP, 0603 0.1µF 10% 25V X7R
TDK C1608X7R1E104K
4
2
C43, C42
CAP, 0603 100pF 5% 25V X7R
AVX 06033C101JAT
5
1
CIN1
CAP, 180µF 20% 16V OSCON
SANYO OSCON 16SVP180MX
6
2
CIN2, CIN3
CAP, 1210 10µF 10% 16V X5R
TAIYO YUDEN EMK325BJ106KN-T
7
2
COUT1, COUT4
CAP, 1210 100µF 20% 6.3V X5R
TDK C3225X5R0J107MT
8
4
COUT2, COUT3, COUT5, COUT6
CAP, 7343 330µF 20% 2.5V POSCAP
SANYO 2R5TPE330M9
9
2
D2, D1
DIODE, CMDSH-3 SOD323
CENTRAL CMDSH-3TR
10
2
L1, L2
IND, 0.4µH
VITEC 59PR9875
11
2
Q1, Q3
XSTR, N-CHANNEL MOSFET
RENESAS RJK0305DPB
12
2
Q2, Q4
XSTR, N-CHANNEL MOSFET
RENESAS RJK0330DPB
13
1
R10
RES, 0603 2.55k 1% 1/10W
VISHAY CRCW06032K55FKEB
14
1
R18
RES, 0603 2.2Ω 5% 1/10W
VISHAY CRCW06032R20JNEA
15
1
R27
RES, 0603 17.8k 1% 1/10W
VISHAY CRCW060317K8FKEA
16
4
R29, R30, R39, R40
RES, 0603 100Ω 5% 1/10W
VISHAY CRCW0603100RJNEA
17
2
R31, R35
RES, 0603 5.9k 1% 1/10W
VISHAY CRCW06035K90FKEA
18
2
R32, R33
RES, 0603 20k 1% 1/10W
VISHAY CRCW060320KFKEA
19
1
R43
RES, 0603 10.0k 1% 1/10W
VISHAY CRCW060310K0FKEB
20
1
R46
RES, 0603 100k 5% 1/10W
VISHAY CRCW0603100KJNEB
21
2
R7, R4
RES, 0603 10k 1% 1/16W
VISHAY CRCW060310K0FKEB
22
3
R8, R9, R25
RES, 0603 0Ω JUMPER
PANASONIC ERJ3GEY0R00V
23
2
RS2, RS1
RES, 2010 0.002Ω 5% 1/2W
VISHAY WSL20102L000FEA
24
1
U1
IC, LTC3850EUF
LINEAR TECH. LTC3850EUF
Additional Circuit Components
1
0
CIN5, CIN4
CAP, 1210 OPTION
OPTION
2
0
C1, C37, C38, C47, C48, C49
CAP, 0603 OPTION
OPTION
3
1
C50
CAP, 0603 1µF 20% 16V X7R
AVX 0603YC105MAT2A
4
0
D4, D3
DIODE, SCHOTTKY 40V 3A OPTION
OPTION
5
0
Q5, Q6, Q7, Q8
DO NOT STUFF
OPTION
6
3
R1, R3, R36
RES, 0603 0Ω JUMPER
PANASONIC ERJ3GEY0R00V
7
0
R2, R26, R28, R34, R37, R38, R41,
R42, R44, R45, R47, R49, R50-R53,
R55, R60-R62
RES, 0603 OPTION
OPTION
1
12
E1-E6, E9-E14
TURRET
MILL-MAX 2501-2-00-80-00-00-07-0
2
2
JP2, JP1
HEADER, 3-PIN, 2mm
SAMTEC TMM-103-02-L-S
3
1
JP3
HEADER, 4-PIN
SAMTEC TMM-104-02-L-S
4
6
J1, J2, J3, J4, J5, J6
JACK, BANANA
KEYSTONE 575-4
5
3
JP1-JP3
SHUNT, 2mm
SAMTEC 2SN-BK-G
Hardware
dc1185b-a/-bf
8
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
D
C
B
A
[1]
E4
E3
E2
E10
0
R2
PGOOD
EXTVCC
OPT
R37
0
OPT
R3
R36
VOUT1
E9
3
1uF
0.1uF
C2
OPT
C38
R8
0
JP2
3
ON
OFF
RUN2
100pF
INTVCC
OPT
OPT
OPT
R44
OPT
OPT
R42
R43
[1]
C49
OPT
4
PGOOD
EXTVCC
ILIM
RUN2
TRK/SS2
ITH2
VFB2
VFB1
ITH1
TRK/SS1
RUN1
FREQ
MODE
100K
R46
INTVCC
12
11
10
9
RUN2
TRK/SS2 6
5
4
VFB2
ITH2
3
VFB1
2
C44
20.0K
ITH1
TRK/SS1 1
26
25
24
JP3
PS BM CCM
RUN1
1
MODE
2
1nF
20.0K
[1]
OPT
R33
R27
C37
R32
C12
1nF
R38
R41
VIN
C48
[1]
R7
INTVCC
10.0K
100pF
R35
C43
C42
R10
[1]
OPT
R26
[1]
1nF
VIN
R31
C41
OPT
R28
1
2
0.1uF
C47
OPT
R34
C50
JP1
1
2
OFF
RUN1
OPT
C1
ON
0
R1
R4
10.0K
INTVCC
3
3
1.8V/10A
1.2V/15A
2.0V/10A
1.5V/15A
-A
-B
1
VOUT2
VOUT1
ASSY
0.002
0.003
RS1, RS2
RENESAS RJK0330DPB
RENESAS RJK0305DPB
RENESAS RJK0305DPB
TOKO FDU0650-R56M=P3
2
3
RENESAS RJK0330DPB
Q1, 3
VITEC 59PR9875 0.4uH
OPT
INTVCC
R39
100
1nF
C15
0
R25
INTVCC
S2-
R60
7
1nF
C14
VINF
R9
8 S2+
13
14
15
16
17
18
19
20
21
22
23
27 S1+
28
S1-
R29
100
R40
100
0.1uF
C17
R18
0
R30
100
17.8K
30.1K
R27
4
VOUT1
10.0K
25.5K
R43
VOUT2
TOP FEED BACK R
STUFF R60 WITH 0 OHMS FOR
4.6V<VIN<5.5V
VINF
SENSE2-
SENSE2+
SW2
TG2
BOOST2
PGND
BG2
INTVCC
VIN
BG1
BOOST1
TG1
SW1
SENSE1+
L1, 2
Q2, 4
4
5
6
VIN
5.9K
8.66K
R31, R35
ITH1 & ITH2
0.1uF
C21
CMDSH-3
D2
4.7uF
C11
2.2
CMDSH-3
D1
0.1uF
C20
5
2.55K
3.16K
R10
OPT
R52
4
RUN2
TRK/SS2
VFB2
ITH2
100uF
47uF
COUT1/COUT4
OPT
OPT
R55
RUN1
TRK/SS1
FSW
OPT
R50
VFB1
ITH1
R49
4
Q4
[1]
Q3
[1]
OPTIONAL JUMPERS FOR
SINGLE OUTPUT/DUAL PHASE
OPERATION
INTVCC
4
Q2
[1]
4
Q1
[1]
4
Q6
OPT
4
Q8
OPT
4
4
VIN
VIN
D4
OPT
VL2-
6
[1]
RS1
ECO
10/31/06
08/05/13
7
R45
S2-
OPT
R53
S1-
OPT
R47
VOUT2
+ COUT3
330uF
2.5V
OPT
VL2-
S2+
VL1-
TECHNOLOGY
R62
OPT
R61
S1+
COUT5 COUT6
+ 330uF + 330uF
2.5V
2.5V
+ COUT2
330uF
2.5V
CIN1
180uF
16V
VOUT1
VIN
J2
VIN-
GND
SCALE:NONE
7
SHEET
DC1185B
FILENAME: 1185B-1.DSN
DWG NO
BUCK CONVERTER
8
X2
on PCB
Tooling Holes
Represents
1
1
VO2-
GND
E14
J6
X1
VOUT2
VO2+
[1]
J5
E13
VO1-
GND
[1]
VOUT1
VO1+
E12
J4
J3
E11
E6
1630 McCarthy Blvd.
Milpitas, CA 95035
Phone: (408)432-1900
Fax: (408)434-0507
C36
4.7uF
6.3V
C32
4.7uF
6.3V
VIN
6.5V - 14V
J1
VIN+
1
OF
1
REV
1
MIKE S.
MIKE S.
08/04/13
E5
APPROVED
12/12/07
8
DATE
SCH, LTC3850EUF, DUAL OUTPUT SYNCHRONOUS
OPT
R51
PROD
+
REVISION HISTORY
DESCRIPTION
CHANGE: Q1,Q2,Q3,Q4
COUT4
{1}
COUT1
{1}
OPT
1.1
1
REV
SIZE CAGE CODE
TITLE
VSW2
VSW1
2010
[1]
RS2
2010
DATE
Tuesday, September 10, 2013
DESIGNER
ENGINEER
APPROVED MIKE S.
CHECKED
DRAWN MEI
APPROVALS
CONTRACT NO.
NOTE:
WHEN DCR SENSING IS
IMPLEMENTED, SHORT RSENSE1 & RSENSE2.
REMOVE R30, R29, R40 & R39
STUFF R61 AND R62 WITH 0 OHMS.
CALCULATE R45, R47, C14 AND
R51, R53 & C15 PER THE DATA
SHEET. ALSO REFER TO QSG
FOR EXAMPLE.
OPTIONAL DCR SENSING
D3
OPT
L2 [1]
OPT
VSW2
Q7
OPT
CIN5
10uF
VL1-
CIN3
VSW1
L1 [1]
OPT
10uF
Q5
OPT
CIN4
CIN2
< 0.6nH/RSENSE FOR 2010 PACKAGE.
NOTE: SET RSENSE FILTER TIME CONSTANT
SENSE1-
LTC3850EUF
U1
NOTE:
1. FSW = 500kHz For Assy - A
2. FSW = 400kHz For Assy - B
3. DO NOT APPLY LOAD FROM THE VO1+ TO VO1- OR FROM THE VO2+ TO VO2- TURRETS.
THESE ARE ONLY INTENDED TO KELVIN SENSE THE OUTPUT VOLTAGE ACROSS COUT1
AND COUT4.
PGOOD
EXTVCC
GND
TRK/SS2
TRK/SS1
SYNC
E1
2
1
2
3
1
SGND
29
5
6
7
8
1
2
3
5
6
7
8
1
2
3
5
6
7
8
1
2
3
5
6
7
8
1
2
3
1
2
3
5
6
7
8
1
2
3
5
6
7
8
5
6
7
8
1
2
3
5
6
7
8
1
2
1
2
1
2
This circuit is proprietary to Linear Technology and supplied
for use with Linear Technology parts.
Customer Notice: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
Applications Engineering for assistance.
D
C
B
A
DEMO MANUAL
DC1185B-A/-B
SCHEMATIC DIAGRAM
dc1185b-a/-bf
9
DEMO MANUAL
DC1185B-A/-B
DEMONSTRATION BOARD IMPORTANT NOTICE
Linear Technology Corporation (LTC) provides the enclosed product(s) under the following AS IS conditions:
This demonstration board (DEMO BOARD) kit being sold or provided by Linear Technology is intended for use for ENGINEERING DEVELOPMENT
OR EVALUATION PURPOSES ONLY and is not provided by LTC for commercial use. As such, the DEMO BOARD herein may not be complete
in terms of required design-, marketing-, and/or manufacturing-related protective considerations, including but not limited to product safety
measures typically found in finished commercial goods. As a prototype, this product does not fall within the scope of the European Union
directive on electromagnetic compatibility and therefore may or may not meet the technical requirements of the directive, or other regulations.
If this evaluation kit does not meet the specifications recited in the DEMO BOARD manual the kit may be returned within 30 days from the date
of delivery for a full refund. THE FOREGOING WARRANTY IS THE EXCLUSIVE WARRANTY MADE BY THE SELLER TO BUYER AND IS IN LIEU
OF ALL OTHER WARRANTIES, EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING ANY WARRANTY OF MERCHANTABILITY OR FITNESS
FOR ANY PARTICULAR PURPOSE. EXCEPT TO THE EXTENT OF THIS INDEMNITY, NEITHER PARTY SHALL BE LIABLE TO THE OTHER FOR
ANY INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES.
The user assumes all responsibility and liability for proper and safe handling of the goods. Further, the user releases LTC from all claims
arising from the handling or use of the goods. Due to the open construction of the product, it is the user’s responsibility to take any and all
appropriate precautions with regard to electrostatic discharge. Also be aware that the products herein may not be regulatory compliant or
agency certified (FCC, UL, CE, etc.).
No License is granted under any patent right or other intellectual property whatsoever. LTC assumes no liability for applications assistance,
customer product design, software performance, or infringement of patents or any other intellectual property rights of any kind.
LTC currently services a variety of customers for products around the world, and therefore this transaction is not exclusive.
Please read the DEMO BOARD manual prior to handling the product. Persons handling this product must have electronics training and
observe good laboratory practice standards. Common sense is encouraged.
This notice contains important safety information about temperatures and voltages. For further safety concerns, please contact a LTC application engineer.
Mailing Address:
Linear Technology
1630 McCarthy Blvd.
Milpitas, CA 95035
Copyright © 2004, Linear Technology Corporation
dc1185b-a/-bf
10 Linear Technology Corporation
LT 1213 • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900
●
FAX: (408) 434-0507 ● www.linear.com
LINEAR TECHNOLOGY CORPORATION 2013