DEMO MANUAL DC2169A
LT8616
Dual 42V Synchronous Monolithic Step-Down
Regulator with 6.5µA Quiescent Current
Description
Demonstration circuit 2169A is a dual monolithic step-down
DC/DC switching regulator featuring the
LT
®
8616.
The
LT8616 is a high efficiency, high speed, dual synchronous
monolithic step-down switching regulator that consumes
only 6.5μA of quiescent current with both channels enabled.
The demo circuit is designed for 5V, 1.5A and 3.3V, 2.5A
outputs. Both channels contain all switches and neces-
sary circuitry to minimize the external components and
solution size. Fast minimum ON time of 35ns enables high
V
IN
to low V
OUT
conversion at high switching frequency.
Independent input voltage, feedback, soft-start and power
good pins for each channel simplify complex power supply
tracking/sequencing requirements.
The inputs of the two channels are connected on the demo
board by default. They can also be separated by removing
the 0Ω resistor (R13) from the board. Each output can
be independently disabled using its own EN/UV pin, while
V
IN1
must be connected to 3.4V or above even if only
channel 2 is in use. The demo board has an EMI filter
installed between V
IN2
and V
EMI
. To use the EMI filter, the
inputs should be tied to V
EMI
.
The switching frequency of both channels can be pro-
grammed either via an oscillator resistor or a common
external clock up to 3MHz.The SYNC pin on the demo
board is grounded by default for Burst Mode
®
operation.
To synchronize to an external clock, move JP1 to SYNC/
MODE and apply the external clock to the SYNC/MODE
turret. The R
T
resistor (R5) should be chosen to set the
LT8616 internal switching frequency at least 20% below
the lowest synchronization input.
Low ripple Burst Mode operation increases the efficiency
at the light load while keeping the output ripple low.
Figure 1 and Figure 2 show the demo board efficiency for
each channel at 12V input voltage in Burst Mode opera-
tion. Figure 3 shows the temperature rising on DC2169A
demo board with different input voltages under full load
conditions on both channels.
The LT8616 data sheet gives a complete description of the
part, operation and application information. The data sheet
must be read in conjunction with this demo manual for
DC2169A. The LT8616 is assembled in a 28-lead plastic
TSSOP package. Proper board layout is essential for both
low EMI operation and maximum thermal performance.
See the data sheet sections for details.
Design files for this circuit board are available at
http://www.linear.com/demo/DC2169A
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.
performance summary
SYMBOL
V
IN1
V
IN2
V
OUT1
V
OUT2
f
SW
I
OUT1
I
OUT2
EFE
PARAMETER
Channel 1 Input Supply Range
Channel 2 Input Supply Range
Channel 1 Output Voltage
Channel 2 Output Voltage
Switching Frequency
Channel 1 Max Output Current
Channel 2 Max Output Current
Efficiency at DC
R
T
= 14.7kΩ
CONDITIONS
Specifications are at T
A
= 25°C
MIN
5.8
4.1
4.88
3.21
1.85
1.5
2.5
5.02
3.29
2.05
TYP
MAX
42
42
5.15
3.37
2.25
UNITS
V
V
V
V
MHz
A
A
85.1
%
dc2169af
V
IN1
= V
IN2
= 12V, I
OUT1
= 1.5A, I
OUT2
= 2.5A
1
DEMO MANUAL DC2169A
performance summary
100
90
EFFICIENCY (%)
80
70
60
50
f
SW
= 2MHz
V
IN1
= 12V
V
OUT1
= 5V
0
0.3
0.9
1.2
0.6
LOAD CURRENT (A)
1.5
DC2169A F01
Figure 1. LT8616 Channel 1 Efficiency vs Load Current
100
90
EFFICIENCY (%)
80
70
60
50
f
SW
= 2MHz
V
IN2
= 12V
V
OUT2
= 3.3V
0
0.5
1.5
1
LOAD CURRENT (A)
2
2.5
DC2169A F02
Figure 2. LT8616 Channel 2 Efficiency vs Load Current
100
f
SW
= 2.05MHz
V
OUT1
= 5V, I
OUT1
= 1.5A
TEMPERATURE RISING (°C)
80
60
40
20
8
16
24
32
INPUT VOLTAGE (V)
40
DC2169A F03
Figure 3. LT8616 Temperature Rising vs Input Voltage
2
dc2169af
DEMO MANUAL DC2169A
Quick start proceDure
DC2169A is easy to set up to evaluate the performance
of the LT8616. Refer to Figure 4 for proper measurement
equipment setup and follow the procedure below:
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 output voltage
ripple by touching the probe tip directly across the V
IN
or V
OUT
and GND terminals. See Figure 5 for the proper
scope technique.
1. Place JP1 on the Burst Mode position.
2. With power off, connect the input power supply to V
EMI
and GND. Make sure that the input voltage does not
exceed 42V.
3. With power off, connect loads from V
OUT1
to GND, and
V
OUT2
to GND.
4. Turn on the power at the input.
5. Check for the proper output voltages (5V and 3.3V).
NOTE: If there is no output, temporarily disconnect the
load to make sure that the load is not set too high or
is shorted.
6. Once the proper output voltages are established, adjust
the load within the operating ranges and observe the
output voltage regulation, ripple voltage, efficiency and
other parameters.
7. An external clock can be added to the SYNC terminal
when SYNC function is used (JP1 on the SYNC/MODE
position). Please make sure that the SYNC frequency is
at least 20% higher than the set switching frequency.
See the data sheet section Synchronization.
Figure 4. Proper Measurement Equipment Setup
V
OUT
GND
Figure 5. Measuring Input or Output Ripple
dc2169af
3
DEMO MANUAL DC2169A
parts List
ITEM
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
1
2
3
4
5
6
7
1
2
3
QTY
2
1
1
2
2
2
5
4
1
1
6
1
1
1
2
1
2
1
1
1
1
2
0
16
1
1
REFERENCE
C2, C3
C4
C5
C6, C7
C8, C9
C10, C11
C12, C17, C19, C27, C28
C13, C14, C15, C16
L1
L2
R1, R3, R6, R8, R10, R11
R2
R4
R5
R7, R13
U1
C1, C18
L3
L4
C23
C24
C25, C26
R9, R12 (OPT)
E1-E16
JP1
XJP1
PART DESCRIPTION
CAP., X7R, 0.1µF, 10V, 10% 0402
CAP., X7R, 22µF, 10V, 10% 1210
CAP., X7R, 47µF, 10V, 10% 1210
CAP., X7R, 0.01µF, 10V, 10% 0603
CAP., C0G, 4.7pF, 50V, ±0.25pF 0603
CAP., X7R, 2.2µF, 50V, 10% 1206
CAP., X7R, 1µF, 10V, 10% 0603
CAP., X7R, 0.1µF, 50V, 10% 0402
IND., 3.3µH, XAL4030
IND., 2.2µH, XFL4020
RES., CHIP, 1M, 0.1W, 1%, 0603
RES., CHIP, 187k, 0.1W, 1%, 0603
RES., CHIP, 316k, 0.1W, 1%, 0603
RES., CHIP, 14.7k, 0.1W, 1%, 0603
RES., CHIP, 0Ω, 0.1W, 0603
IC., LT8616EFE TSSOP-28/EB
CAP., ALUM., 22µF, 63V,
CHIP BEAD, 30Ω, MPZ2012
IND., 0.22µH, IHLP1212AB
CAP., X7R, 4.7µF, 50V, 10% 1206
CAP., X7R, 10µF, 50V, 10% 1210
CAP., X7R, 0.1µF, 50V, 10% 0402
RES., CHIP, 0603
TESTPOINT, TURRET, .094" PBF
4 PIN 0.079 SINGLE ROW HEADER
SHUNT, .079" CENTER
MILL-MAX, 2501-2-00-80-00-00-07-0
SULLINS, NRPN041PAEN-RC
SAMTEC, 2SN-BK-G
MANUFACTURER/PART NUMBER
SAMSUNG, CL05B104KP5NNNC
MURATA, GRM32ER71A226KE20L
MURATA, GRM32ER71A476KE15L
AVX, 0603ZC103KAT2A
AVX, 06035A4R7CAT2A
MURATA, GRM31CR71H225KA88L
AVX, 0603ZC105KAT2A
TDK, C1005X7R1H104K050BB
COILCRAFT, XAL4030-332ME
COILCRAFT, XFL4020-222ME
VISHAY, CRCW06031M00FKEA
VISHAY, CRCW0603187KFKEA
VISHAY, CRCW0603316KFKEA
VISHAY, CRCW060314K7FKEA
VISHAY, CRCW06030000Z0EA
LINEAR TECH., LT8616EFE#PBF
SUN ELECTRONIC INDUSTRIES CORP., 63CE22BS
TDK, MPZ2012S300AT
VISHAY, IHLP1212ABERR22M11
SAMSUNG, CL31B475KBHNNNE
MURATA, GRM32ER71H106KA12L
TDK, C1005X7R1H104K050BB
Required Circuit Components
Additional Demo Board Circuit Components
Hardware: For Demo Board Only
4
dc2169af
5
4
3
2
1
D
D
VIN1
VIN1
R11
1M
+
R13
0
VIN2
C14
0.1uF
50V
0402
C16
0.1uF
50V
0402
C11
2.2uF
50V
1206
R9
OPT
C18
22uF
63V
63CE22BS
E11
R8
1M
E10
5.8V - 42V
C10
2.2uF
50V
1206
C15
0.1uF
50V
0402
C13
0.1uF
50V
0402
E1
VIN2
4.1V - 42V
PAD150-094
+
20
18
23
19
schematic Diagram
E2
NC
NC
NC
24
VIN1
EN1
E15
C2
10V
0402
R12
OPT
U1
LT8616EFE
16
VIN2
NC
25
GND
C1
22uF
63V
63CE22BS
GND
EN/UV1
BOOST1
BOOST2
10V
0402
XFL4020-222ME
C9
R4
316K
1M
R3
4.7pF
VOUT2
C5
47uF
10V
1210
C27
1uF
L2
2.2uH
ENUV2
BIAS
6
3
4
5
26
27
C3
0.1uF
1
22
R7
0
8
9
10
SW1
SW1
FB1
FB1
TR/SS1
TR/SS2
PG2
17
SYNC/MODE
RT
GND
NC
15
29
7
21
R6
1M
E13
EN2
L1
0.1uF
R1
1M
3.3uH
XAL4030-332ME
C8
4.7pF
R2
187k
C
VOUT1
C
5V / 1.5A
C4
22uF
10V
1210
E3
VOUT1
C17
1uF
GND
C28
1uF
13
14
12
C7
0.01uF
SW2
SW2
SW2
FB2
FB2
E5
C19
1uF
E4
VOUT2
3.3V / 2.5A
GND
E6
E12
E14
PG2
PG1
SS1/TR1
C6
0.01uF
E9
28
2
11
SS2/TR2
E8
PULSE SKIPPING
BURST MODE
1
2
3
4
JP1
4 Pins 2mm Ctrs.
C12
1uF
INTVCC
PG1
SYNC/MODE
E7
SYNC
R10
1M
VOUT2
VOUT1
B
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 representa-
tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.
SYNC/MODE
R5
14.7k
2MHz
L3
30 ohm
MPZ2012S300AT
VIN2
C23
4.7uF
50V
1206
C24
10uF
50V
1210
L4
0.22uH
IHLP1212ABERR22M11
B
VEMI
E16
C25
0.1uF
50V
0402
C26
0.1uF
50V
0402
CUSTOMER NOTICE
A
NOTE: UNLESS OTHERWISE SPECIFIED
LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A
CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS;
TECHNOLOGY
HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO
VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL
APPLICATION. COMPONENT SUBSTITUTION AND PRINTED
TITLE: SCHEMATIC
CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT
DUAL 42V SYNCHRONOUS
PERFORMANCE OR RELIABILITY. CONTACT LINEAR
TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE.
1630 McCarthy Blvd.
Milpitas, CA 95035
Phone: (408)432-1900
www.linear.com
Fax: (408)434-0507
LTC Confidential-For Customer Use Only
A
SIZE
THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
4
3
2
MONOLITHIC
STEP-DOWN REGULATOR WITH 6.5µA QUIESCENT CURRENT
N/A
DATE:
IC NO.
REV.
1. ALL RESISTORS ARE IN 0603
ALL CAPACITORS ARE IN 0603
Monday, January 19, 2015
LT8616EFE
DEMO CIRCUIT 2169A
4
SHEET
1
1
OF
1
5
DEMO MANUAL DC2169A
dc2169af
5
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