DC1956A - Demo Manual

DEMO MANUAL DC1956A
LT3905
Boost DC/DC Converter with
APD Current Monitor
Description
The LT3905 data sheet gives a complete description of
the part, operation, and application information. The data
sheet must be read in conjunction with this Quick Start
Guide for the DC1956A.
Design files for this circuit board are available at
http://www.linear.com/demo/DC1956A
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
For measuring fast transient response, use the installed
Fast Monitor Response Circuit on the bottom of the demo
board and install 0Ω resistors at R14 and R20. Also, remove
R11 and any other capacitances or probes across the APD
node. The transient response should be measured at the
TIA turret. For further information, read the APD Current
Monitor Transient Response section in the data sheet.
The internal LOS_MON comparator hysteresis is 20mV on
the rising edge of the LOS_MON voltage. For additional
hysteresis, use R6, R7, R15, and R21 as stated in the Loss
of Signal Hysteresis section in the data sheet.
100
VAPD = 50V
80
INPUT CURRENT (mA)
Demonstration circuit 1956A features the LT®3905, a boost
DC/DC Converter with APD current monitor that comes in
a 3mm × 3mm QFN package. This demo board is designed
to convert a 2.7V to 12V input to a 50V output at 2mA. The
LT3905 is equipped with indicators for monitoring APD
current, overload, and loss-of-signal (LOS) conditions,
which can easily be changed with their respective resistors. In addition, the output voltage can be adjusted via the
CTRL pin. DC1956A is designed for 1MHz operation but
can also be programmed for 2MHz by moving jumper JP2.
60
40
20
0
VIN = 3.3V
VIN = 5V
0
0.5
1.5
1
IAPD (mA)
2
DC1956A F01
Figure 1. DC1956A Input Current vs APD Current
Performance Summary
Specifications are at TA = 25°C
SYMBOL
PARAMETER
CONDITIONS
VIN
Input Supply Range
12
V
VOUT
Output Voltage Range
VIN = 3.3V, IAPD = 1mA
48
50
52
V
fSW
Switching Frequency
JP2: 1MHz
0.9
1
1.1
MHz
MIN
TYP
2.7
MAX
UNITS
ILOS
Loss-of-Signal APD Current
R10 = 1MΩ
12.5
µA
ILIM
APD Current Limit
R8 = 12.4kΩ
2
mA
VMON/IAPD
MON Voltage to APD Current Ratio
R11 = 4.99kΩ
1
mV/µA
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1
DEMO MANUAL DC1956A
Quick Start Procedure
Demonstration circuit 1956 is easy to set up to evaluate
the performance of the LT3905. Refer to Figure 2 for
proper measurement equipment setup and follow the
procedure below:
NOTE. When measuring the output voltage ripple, connect
a BNC cable from the oscilloscope to J1. Make sure there
are no other cables connected to the APD node.
1.Place jumpers in the following positions:
JP1:Run
JP2:1MHz
2.With power off, connect the input power supply to VIN
and GND.
2
3.Turn on the power at the input.
NOTE: Make sure that the input voltage does not exceed
16V.
4.Connect a 50K resistor from APD to GND and check for
the proper output voltage. VOUT = APD = 48V to 52V.
NOTE: 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 voltages are established, adjust
the loads within the operating range and observe the
output voltage regulation, ripple voltage, efficiency and
other parameters.
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DEMO MANUAL DC1956A
Quick Start Procedure
Figure 2. Proper Measurement Equipment Setup
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3
DEMO MANUAL DC1956A
Parts List
ITEM
QTY
REFERENCE
PART DESCRIPTION
MANUFACTURER/PART NUMBER
Required Circuit Components
1
1
C1
CAP., X7R, 1µF, 25V, 10% 0805
AVX, 0805YC105KAT2A
2
1
C5
CAP., X7R, 0.22µF, 100V, 10% 1206
AVX, 12061C224KAT2A
3
1
L1
INDUCTOR, 10µH
COOPER Bussmann, SD3110-100-R
4
3
R1, R4, R5
RES., CHIP, 100k, 1/10W, 1% 0603
VISHAY, CRCW0603100KFKEA
5
3
R3, R7, R10
RES., CHIP, 1M, 1/10W, 1% 0603
VISHAY, CRCW06031M00FKEA
6
1
R8
RES., CHIP, 12.4k, 1/10W, 1% 0603
VISHAY, CRCW060312K4FKEA
7
1
R11
RES., CHIP, 4.99k, 1/10W, 1% 0603
VISHAY, CRCW0603604KFKEA
8
1
R12
RES., CHIP, 634k, 1/10W, 1% 0603
VISHAY, CRCW0603634KFKEA
9
1
R13
RES., CHIP, 15.0k, 1/10W, 1% 0603
VISHAY, CRCW060315K0FKEA
10
2
R15, R16
RES., CHIP, 0, 1/10W, 1% 0603
VISHAY, CRCW0603000Z0EA
11
1
U1
I.C. LT3905EUD, 16 PIN, 3×3mm
LINEAR TECH, LT3905EUD#PBF
Additional Demo Board Circuit Components
1
0
C2, C3, C4, C6 (OPT)
CAP., 0603
2
0
C8 (OPT)
CAP., 0805
3
1
C9
CAP., C0G, 0.5pF, 50V, 5% 0603
AVX, 06035A0R5KJAT2A
4
1
C10
CAP., X7R, 0.1µF, 16V, 10% 0603
AVX, 0603YC104KAT2A
5
2
C11, C12
CAP., X7R, 1µF, 16V, 10% 0603
AVX, 0603YC105KAT2A
6
1
Q1
TRANS., NPN 100V 2.5A MED SOT23-3
DIODES / ZETEX, ZXTN25100DFHTA
7
0
R2, R6, R9, R14, R20, R21
RES., 0603
8
2
R18, R19
RES., CHIP, 4.99k, 1/10W, 1% 0603
VISHAY, CRCW0603604KFKEA
9
1
R17
RES., CHIP, 1k, 1/10W, 1% 0603
VISHAY, CRCW06031K00FKEA
10
1
U2
I.C., LT6210CS6, TSOT23-6
LINEAR TECH, LT6210CS6#PBF
11
1
U3
I.C., LT1790BIS6-2.048, TSOT23
LINEAR TECH, LT1790BIS6-2.048
Hardware: For Demo Board Only
4
1
14
E1-E14
TESTPOINT, TURRET, .094" pbf
MILL-MAX, 2501-2-00-80-00-00-07-0
2
2
JP1, JP2
3 PIN 0.079 SINGLE ROW HEADER
SULLINS, NRPN031PAEN-RC
3
2
XJP1, XJP2
SHUNT, .079" CENTER
SAMTEC, 2SN-BK-G
4
1
J1
CONN, BNC, 5 PINS
CONNEX 112404
5
4
Stand-Off
STAND-OFF, NYLON 0.25"
KEYSTONE, 8831(SNAP ON)
dc1956afa
A
B
C
D
U3
C11
1uF
R20
OPT
E9
E7
E8
E6
E5
E4
E3
E1
5
3
NC
5
VIN
R3
1M
NC
VIN
LT1790BIS6-2.048
MON
MON
ILIM_MON
LOS_MON
LOS ADJ
LOS
ILIM
CTRL
EN
E10
E2
OUT
OPT
R14
6
1MHz
2MHz
JP2
C12
1uF
R19
4.99K
R2
OPT
C3
OPT
C10
0.1uF
R18
C9
0
R15
R1
100K
V-
V+
1
14
13
TIA
4
2
R11
4.99K
(1mV/uA)
OPT
C2
OPT
R9
LOS_MON
LOS_ADJ
LOS
ILIM
CTRL
FSEL
3
8
3
R8
12.4K
(2mA Limit)
3
ILIM_MON
4
MON
VOUT
U1
LT3905EUD
7
SW
10
EN/UVLO
C4
OPT
R21
OPT
R5
100K
12
16
11
L1
10uH
VIN
COPPER
BUSSMANN
SD3110-100-R
R10
1M
(12.5uA LOS)
R6
OPT
R4
100K
E12
U2
LT6210CS6
4.99K
0.5pF
VIN
VIN
JP1
RUN SHDN
1
3
4
FAST MONITOR RESPONSE CIRCUIT
VIN
2
R7
1M
VIN
C1
1uF
25V
0805
1
3
GND
VIN
Iset
2
VIN
2.7V - 12V
4
VIN
GND
2
GND
1
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.
+
-
5
6
GND
GND
APD
FB
17
9
5
15
0
R16
R17
1K
E11
Q1
ZXTN25100DFH
C6
OPT
LOAD STEP CIRCUIT
R13
15.0K
R12
634K
PWM
2
1. ALL RESISTORS ARE 0603.
ALL CAPACITORS ARE 0603.
NOTE: UNLESS OTHERWISE SPECIFIED
MON
MONIN
C5
0.22uF
100V
1206
2
E14
E13
C8
OPT
100V
0805
BNC
1
1
GND
50V / 2mA
APD
J1
A
B
C
D
DEMO MANUAL DC1956A
Schematic Diagram
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5
DEMO MANUAL DC1956A
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
6
dc1956afa
Linear Technology Corporation
LT 0114 REV A • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900
●
FAX: (408) 434-0507 ● www.linear.com
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