1
DEMO MANUAL DC2846A
Rev. 0
DESCRIPTION
LTC7804
Low IQ Synchronous Boost
Controller
Demonstration circuit DC2846A is a DC/DC synchronous
boost converter featuring the LT C
®
7804 (MSE package),
a spread spectrum or constant frequency current mode
synchronous boost controller. The DC2846A generates
a 24V output voltage and provides up to 6A of output
current.
The 500kHz constant switching frequency operation
results in a small and efficient circuit.
The main features of this board include:
•Wide input voltage range: from 6V to 24V
• Relatively high output power, up to 150W
•Extremely low quiescent current, it’s 15µA at sleep
mode and as low as 1µA at shutdown
• Onboard low power bias supply
• Ability to select spread spectrum or fixed frequency
•Pulse-skipping mode, forced continuous operation or
low ripple Burst Mode
®
operation at light loads
• Synchronization with external clock
All registered trademarks and trademarks are the property of their respective owners.
PERFORMANCE SUMMARY
•If VIN > VOUT, the DC2846A eliminates the usual
boost topology losses by keeping the top MOSFET on
continuously.
The converter provides high output voltage accuracy
(typically ±2%) over a wide load range with no minimum
load requirement.
The DC2846A supports two ways of biasing step-up con-
trollers: directly from the input voltage or output rail. The
third possibility is connecting voltage source to EXTVCC
terminal.
The DC2846A extremely wide switching frequency range
from 100kHz to 3MHz. It can be synchronized to the
external clock anywhere inside this range. The spread
spectrum operation is used for reducing the peak radi-
ated and conducted noise to simplify compliance with
electromagnetic interference (EMI) standards
The DC2846A has small circuit footprint. It is a high per-
formance and cost-effective solution for telecom, auto-
motive and Power over Ethernet applications.
Design files for this circuit board are available.
Specifications are at TA = 25°C
PARAMETER CONDITIONS VALUE UNITS
Minimum Input Supply Voltage 6 V
Maximum Input Supply Voltage 24 V
Output Voltage Range VIN = 6V to 20V 24±2% V
Typical Switching Frequency 500 kHz
Typical Output Ripple (VOUT, 48V) ILOAD = 3A 200 mV
Efficiency Typical (VOUT, 48V, VIN 12V) 95 %
2
DEMO MANUAL DC2846A
Rev. 0
QUICK START PROCEDURE
Demonstration circuit 2846 is easy to set up to evalu-
ate the performance of the LTC7804 controllers. Refer to
Figure1 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 VIN or
VOUT and GND terminals. See Figure2 for proper scope
probe technique.
1. Place jumper RUN (J2) in ON position, place jumper
MODE (JP1) in PULSE SKIP position, place jumper
FREQSET (JP4) into FIX FREQ position.
2. Place jumper VBIAS (JP3) in VIN position.
3. With power off, connect the input power supply to VIN
and GND.
Turn the input power source on and slowly increase the
input voltage to 12V. Be careful not to exceed 24V.
Figure1. Proper Measurement Equipment Setup
3
DEMO MANUAL DC2846A
Rev. 0
QUICK START PROCEDURE
Figure2. Measuring Input or Output Ripple
Figure3. Efficiency vs Load for Different Input Voltage Figure4. Maximum Output Current vs Input Voltage
NOTE: Make sure that the input voltage VIN does not
exceed 20V. If higher operating voltage is required, power
components with higher voltage ratings should be used.
4. Check for the proper output voltage of 24V. If there
is no output, temporarily disconnect the load to make
sure that the load is not set too high.
5. Once the proper output voltage is established, adjust
the load within the operating range and observe the
output voltage regulation, ripple voltage, efficiency and
other parameters.
To synchronize DC2846A with external clock insert jumper
FREQSET (JP4) in SYNC position and apply clock signals
to terminal SYNC (E6).
CONVERTER EFFICIENCY
DC2846SA yields 96% efficiency at 16V input voltage gen-
erating 24V at 6A, see Figure3. DC2846A able to deliver
6A output current down to 9V of input; however, output
current should be reduced at lower voltage per Figure4.
All efficiency measurements were conducted at room
temperature, natural convection cooling with no air flow.
DC2846A SPRED SPECTRUM
The demo board DC2846AA shipped with fixed frequency
operation. To employ the spread spectrum operation,
insert the jumper PLLIN/SPREAD (JP4) in into SPREAD
position. In this setting the switching frequency will
change in ±15% range relatively to the preset value.
GNDVIN
INPUT VOLTAGE (V)
6
OUTPUT CURRENT (A)
7
6
4
2
5
3
1
087 9
DC2846A F04
7.56.5 8.5
LOAD CURRENT (A)
0
EFFICIENCY (%)
9V
12V
16V
20V
96
97
94
91
95
92
90
89 42 6
DC2846A F03
31 5
4
DEMO MANUAL DC2846A
Rev. 0
PARTS LIST
ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER
Required Circuit Components
1 1 C2 CAP, 100pF, C0G, 25V, 10%, 0603 AVX, 06033A101KAT2A
2 1 C3 CAP, 1500pF, X7R, 25V, 10%, 0603 AVX, 06033C152KAT2A
3 2 C4, C15 CAP, 0.1µF, X5R, 25V, 10%, 0603 AVX, 06033D104KAT2A
4 1 C5 CAP, 1000pF, C0G, 25V, 10%, 0603 AVX, 06033A102KAT2A
5 1 C8 CAP, 4.7µF, X5R, 25V, 10%, 0805 MURATA, GRM219R61E475KA73D
6 2 C19, C23 CAP, 1µF, X5R, 50V, 10%, 0603 AVX, 06035D105KAT2A
7 2 CIN1, COUT5 CAP, 150µF, ALUM ELECT, 35V, 20%, SMD SUN ELECT, 35HVH150M
8 9 CIN2, CIN3, CIN4, CIN5,
COUT1, COUT2, COUT3,
COUT4, COUT6
CAP, 10µF, X5R, 50V, 10%, 1210 TDK, C3225X5R1H106K250AB
9 1 D1 DIODE, SCHOTTKY, 60V, 1A, SOD-123F DIODES, B160S1F-7
10 1 L1 IND, 2.8µH, WE-HCI, FLAT WIRE, SMD WURTH, 7443551280
11 2 Q1,Q4 XSTR, MOSFET, N-CH, 40V, 98A, TDSON-8 INFINEON, BSC032N04LS
12 5 R2, R5, R6, R13, R16 RES, AEC-Q200, 0Ω, 1/10W, 0603 VISHAY, CRCW06030000Z0EA
13 1 R4 RES, AEC-Q200, 16.9kΩ, 1%, 1/10W, 0603 NIC, NRC06F1692TRF
14 1 R9 RES, 100Ω, 1%, 1/10W, 0603 YAGEO, RC0603FR-07100RL
15 1 R10 RES, AEC-Q200, 232kΩ, 1%, 1/10W, 0603 VISHAY, CRCW0603232KFKEA
16 1 R12 RES, AEC-Q200, 12.1kΩ, 1%, 1/10W, 0603 VISHAY, CRCW0603100KFKEA
17 1 R14 RES, AEC-Q200, 100kΩ, 1%, 1/10W,0603 VISHAY, CRCW0603100KFKEA
18 1 R18 RES, AEC-Q200, 76.8kΩ, 1%, 1/10W, 0603 PANASONIC, ERJ3EKF7682V
19 1 R19 RES, AEC-Q200, 1MΩ, 1%, 1/10W, 0603 VISHAY, CRCW06031M00FKEA
20 1 R20 RES, 200kΩ, 1%, 1/10W, 0603 VISHAY, CRCW0603200KFKEA
21 1 R22 RES, AEC-Q200, 1kΩ, 1%, 1/10W, 0603 VISHAY, CRCW06031K00FKEA
22 2 RSNS1, RSNS2 RES, SENSE, AEC-Q200, 0.005Ω, 1%, 1/2W, 2010 VISHAY, WSL20105L000FEA
23 1 U1 IC, LOW IQ SYNC BOOST CONTROLLER, SSOP-16 ANALOG DEV INC, LTC7804EMSE#PBF
Additional Demo Board Circuit Components
1 C7, C20, C21, C22 CAP, OPTION, 0603 OPT
2 COUT7 CAP, OPTION, ALUM ELECT, SMD OPT
3 Q2, Q3 XSTR, OPTION, MOSFET N-CH, PG-TDSON-8 OPT
4 R1, R3, R7, R8, R11, R15, R17 RES, OPTION, 0603 OPT
Hardware: For Demo Board Only
1 10 E1, E2, E3, E4, E5, E6, E7, E8,
E9, E10
TEST POINT, TURRET, 0.094", MTG HOLE MILL-MAX, 2501-2-00-80-00-00-07-0
2 4 J1, J2, J3, J4 CONN, BANANA JACK, FEMALE, THT, NON-INSULATED,
SWAGE
KEYSTONE, 575-4
3 2 JP1, JP4 CONN, HDR, MALE, 2 × 3, 2mm, VERT, STR, THT WURTH, 62000621121
4 2 JP2, JP3 CONN, HDR, MALE, 1 × 3, 2mm, STR, THT WURTH, 62000311121
5
DEMO MANUAL DC2846A
Rev. 0
Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog
Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications
subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
SCHEMATIC DIAGRAM
5
5
4
4
3
3
2
2
1
1
D D
C C
B B
A A
NOTE: UNLESS OTHERWISE SPECIFIED
1. ALL RESISTORS AND CAPACITORS ARE 0603.
PROD
DESCRIPTIONREV
REVISION HISTORY
DATE APPROVED
3
ECO
i ^
-03/29/19
* FOLLOW DERATING CHART IN DEMO MANUAL.
VOUT
VBIAS
VOUT
VIN
EXTVCC
INTVCC INTVCC
EXTVCC
INTVCC
VIN
VIN
VOUT
VIN
VBIAS
VIN
INTVCC
INTVCC
DATE:
IC NO.
SHEET OF
TITLE: DEMO CIRCUIT SCHEMATIC,
APPROVALS
PCBDES.
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Milpitas,CA95035
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LTC7804EMSE
DC2846A
700-DC2846A_REV03
705-DC2846A_REV03
N/A
Friday, March 29, 2019
710-DC2846A_REV03
HIGH EFFICIENCY SYNCHRONOUS STEP-UP SUPPLY
DATE:
IC NO.
SHEET OF
TITLE: DEMO CIRCUIT SCHEMATIC,
APPROVALS
PCBDES.
APPENG. Phone:1‐408‐432‐1900
Milpitas,CA95035
1630McCarthyBlvd.
ForADICustomerUseOnly
CUSTOMER NOTICE
ANALOGDEVICESINC.HASMADEABESTEFFORTTODESIGNA
CIRCUITTHATMEETSCUSTOMER‐SUPPLIEDSPECIFICATIONS;
HOWEVER,ITREMAINSTHECUSTOMER'SRESPONSIBILITYTO
VERIFYPROPERANDRELIABLEOPERATIONINTHEACTUAL
APPLICATION.COMPONENTSUBSTITUTIONANDPRINTED
CIRCUITBOARDLAYOUTMAYSIGNIFICANTLYAFFECTCIRCUIT
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SIZE:
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LTC7804EMSE
DC2846A
700-DC2846A_REV03
705-DC2846A_REV03
N/A
Friday, March 29, 2019
710-DC2846A_REV03
HIGH EFFICIENCY SYNCHRONOUS STEP-UP SUPPLY
DATE:
IC NO.
SHEET OF
TITLE: DEMO CIRCUIT SCHEMATIC,
APPROVALS
PCBDES.
APPENG. Phone:1‐408‐432‐1900
Milpitas,CA95035
1630McCarthyBlvd.
ForADICustomerUseOnly
CUSTOMER NOTICE
ANALOGDEVICESINC.HASMADEABESTEFFORTTODESIGNA
CIRCUITTHATMEETSCUSTOMER‐SUPPLIEDSPECIFICATIONS;
HOWEVER,ITREMAINSTHECUSTOMER'SRESPONSIBILITYTO
VERIFYPROPERANDRELIABLEOPERATIONINTHEACTUAL
APPLICATION.COMPONENTSUBSTITUTIONANDPRINTED
CIRCUITBOARDLAYOUTMAYSIGNIFICANTLYAFFECTCIRCUIT
PERFORMANCEORRELIABILITY.CONTACTANALOGDEVICES
INC.APPLICATIONSENGINEERINGFORASSISTANCE.
THISCIRCUITISPROPRIETARYTOANALOGDEVICESINC.AND
SUPPLIEDFORUSEWITHANALOGDEVICESINC.PARTS.
SCALE=NONE
SIZE:
SKU NO. SCHEMATIC NO. AND REVISION:
PCABOM:
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LTC7804EMSE
DC2846A
700-DC2846A_REV03
705-DC2846A_REV03
N/A
Friday, March 29, 2019
710-DC2846A_REV03
HIGH EFFICIENCY SYNCHRONOUS STEP-UP SUPPLY
+
COUT7
OPT
C7
OPT
R16
0E4
GND
R20
200k
1%
+
COUT5
150uF
35V
12
R15
TBD
R17
OPT
C2 100pF
C8
4.7uF
0805
C21
OPT
R9 100
E9
GND
JP3
VOUT
VIN
VBIAS
1
3
2
J2
GND
JP1
MODE
CCM
PULSE SKIP
BURST MODE
1 2
3 4
5 6
C4
0.1uF R11 OPT
C15
0.1uF
R12
12.1k
1%
J3
VIN
6V-24V
E1
VOUT
E8
GND
R7
OPT
R22 1k 1%
C20
OPT
R3
OPT
E3
VIN
R8
OPT
J1
VOUT
24V/6A*
CIN4
D1
BAS140W
L1 3.7uH
7443551370
RSNS2
0.005
2010
1%
R5
0
R13
0
E7
EXTVCC
Q1
BSC032N04LS
5
6
1
7
4
2
3
8
CIN5
RSNS1
0.005
2010
1%
R19
1M
1%
E6
SYNC
R6
0
+
CIN1
150uF
35V
12
R14
100k CIN3
R10
232k
1%
R18
86.6k
1%
COUT3
COUT6
U1
LTC7804EMSE
VFB
4
SENSE1+
3
SENSE1-
2
ITH
5
TRACK/SS
1
MODE
9
FREQ
7
RUN
6PLLIN/SPREAD 8
BG 13
INTVCC 10
EXTVCC 11
BOOST 14
TG 15
SW 16
VIN 12
GND
17
Q4
BSC032N04LS
5
6
1
7
4
2
3
8
Q3
OPT
5
6
7
4
2
3
8
1
R4
16.9k
CIN2 10uF
1210
50V
JP2
ON
OFF
RUN
1
3
2
Q2
OPT
5
6
7
4
2
3
8
1
C5
1000pF
R1
OPT
C19 OPT
COUT4
C23 1uF
C3
1500pF
COUT2
E5
SS
COUT1 10uF
1210
50V
E10
GND
R2 0
JP4
FREQ SET
SPREAD
SYNC
FIX FREQ.
12
34
56
R21
0
E2
GND
J4
GND
SNS-
CS+
SNS-
CS+
CS-
SS
RUN
CS-
6
DEMO MANUAL DC2846A
Rev. 0
ANALOG DEVICES, INC. 2020
01/20
www.analog.com
ESD Caution
ESD (electrostatic discharge) sensitive device. Charged devices and circuit boards can discharge without detection. Although this product features patented or proprietary protection
circuitry, damage may occur on devices subjected to high energy ESD. Therefore, proper ESD precautions should be taken to avoid performance degradation or loss of functionality.
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