DC1741A - Demo Manual

DEMO MANUAL DC1741A
LTC4370
Two-Supply Diode-OR
Current Balancing Controller
DESCRIPTION
Demonstration circuit DC1741A features the LTC4370, a
two supply diode-OR current sharing controller in a typical
2.9V to 18V, 16A sharing application.
The maximum MOSFET voltage drop VFR = VIN – OUT is
set with an external resistor, up to 600mV. A fast gate
turn-on reduces the load voltage droop during supply
switchover. If the input supply fails or is shorted, a fast
turn-off minimizes the transient reverse current.
Disabling the load sharing function turns the LTC4370
into a dual ideal diode controller.
Two enable input pins, EN1 and EN2, allow enabling and
disabling each rail’s MOSFET individually while the MOSFETs’ inherent diodes create diode-OR connection when
the MOSFETs are disabled. The LTC4370 provides a rich
PERFORMANCE SUMMARY
SYMBOL
PARAMETER
VIN
VIN1 and VIN2 Input Voltage Operating Range
• Elimination of "Share Bus”
• Reverse Current Blocking
• Elimination of Shoot-Through Current During Start-Up
or Faults
Design files for this circuit board are available at
http://www.linear.com/demo
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.
MIN
MAX
UNITS
18
VCC
V
With External VCC Supply
2.9
0
VIN1, VIN2 ≤ VCC
2.9
6.0
V
5
5.5
V
0
±2
mV
VCC(REG)
VCC Regulated Voltage
VEA(OS)
Error Amplifier Input Offset
gm(EA)
Error Amplifier Gain
VFR
Forward Regulation Voltage (VIN – VOUT)
VIN =1.2V, VCC = 5V
VIN =12V
ΔVGATE
MOSFET Gate Drive (GATE-VIN)
IGATE
GATE1, GATE2 Fast Pull-Up Current
GATE1, GATE2 Fast Down-Up Current
GATE1, GATE2 Off Pull-Down Current
VEN(TH)
EN1, EN2 Threshold Voltage
Maximum Continuous Load Current
• Elimination of the Need for Active Control of Input
Supplies
CONDITIONS
VCC External Supply Operating Range
IOUT
• Load Sharing Between Two Supplies
Specifications are at TA = 25°C
VCC(EXT)
ΔVGATE(ON) MOSFET On-Detect Threshold (GATE-VIN)
set of features to support shared current diode-ORed applications including:
4.5
TYP
150
μS
2
2
12
25
25
50
mV
mV
VFWD = 0.2V; I = 0, –1μA; Highest VIN = 12V
VFWD = 0.2V; I = 0, –1μA; Highest VIN = 2.9V
10
4.5
12
7
14
9
V
V
VFWD = 0.4V, ΔVGATE = 0V, CPO = 17V
VFWD = –2V, ΔVGATE = 5V,
Corresponding EN =1V, ΔVGATE = 2.5V
–0.9
0.9
65
–1.4
1.4
110
–1.9
1.9
160
A
A
μA
EN Falling
580
600
620
mV
FETON Transitions High
0.28
0.7
1.1
V
16.6
A
Sharing active, limited by SUM85N03 FET Dissipation
dc1741af
1
DEMO MANUAL DC1741A
OPERATING PRINCIPLES
The LTC4370 controls N-channel MOSFETs, M1 and
M2, to share the load between two input rails.The error
amplifier compares OUT1 and OUT2, and controls servo
amplifiers which regulate MOSFET forward voltage drop
to VFR. Combined action of the error amplifier and servo
amplifiers forces OUT1 and OUT2 to be equal and as a
result the rail currents are equal. The board RANGE resistor
R3 = 30.1k defines maximum regulation voltage range as
265mV to 375mV.
The board is assembled with SUM85N03-06P N-channel
MOSFETs, which in a single channel application has
current capability up to 20A. In the load share mode the
installed components guarantee continuous proper load
sharing up to 16.6A total load. For a short test time of 3
to 5 seconds it is possible to double this load.
Two LEDs, OFF1 and OFF2, indicate the MOSFETs’ status.
Each LED lights up, when the gate voltage is less than
0.7V above VIN.
Pay special attention to the power supply features used
with the LTC4370.
This controller may not work properly with supplies utilizing
synchronized rectification in the output stage unless the
internal circuit of the supply has the ability to limit negative
current or to block it completely. Exercise caution when
using the controller with this type of supply unless it is
determined that it contains the required circuitry.
dc1741af
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DEMO MANUAL DC1741A
QUICK START PROCEDURE
Demonstration circuit DC1741A is easy to set up to evaluate the performance of the LTC4370. Refer to Figure 1
for proper measurement equipment setup for load share
observation.
1. Turn both supplies on. Adjust two 5V supplies’ outputs
to a 215mV difference, which equals the minimum
ΔVIN(MIN) load share breakpoint (265mV–50mV).
Load the LTC4370 output with minimal current so that
both supplies contribute current to the common load.
Increase load up to 35A and observe the LTC4370 operation mode with accurate load sharing. It is easy to
estimate load share accuracy by measuring a voltage
between two sense resistors. Since the MOSFETs will
be dissipating excessive power, limit this measurement
to 3 to 5 seconds when at the 35A level.
2. Reduce the load current to a total of 7.5A. Adjust the
two 5V supplies’ outputs to a voltage difference of 373
mV which equals the maximum ΔVIN(MAX) load share
breakpoint (375mV–2mV). As the difference between
power supplies output is greater than the maximum
voltage regulation, the LTC4370 channel with the higher
voltage will provide most of the current. Increase the
voltage until all of the current is provided by the higher
voltage supply. This is the point at which the MOSFET
of the higher voltage channel MOSFET is fully enhanced
while the MOSFET of the lower channel voltage is
completely cut off. Observe that the LED of the lower
supply is illuminated.
VARIABLE
LOAD
+
POWER
SUPPLY 1
–
mV
+
POWER
SUPPLY 2
–
DC1741A F01
Figure 1. Load Share Performance Measurement
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DEMO MANUAL DC1741A
PARTS LIST
ITEM
QTY
REFERENCE
PART DESCRIPTION
MANUFACTURER/PART NUMBER
Cap., X7R, 0.18μF, 25V, 10%, 0805
AVX, 08053C184KAT2A
Required Circuit Components
1
1
CC
2
1
CVCC
Cap., X7R, 0.1μF, 50V, 10%, 0805
AVX, 08055C104KAT2A
3
2
C1, C2
Cap., X7R, 0.039μF, 50V, 10%, 0805
AVX, 08055C393KAT2A
4
2
D1, D2
LED, RED
Panasonic, LN1251C-TR
5
2
D3, D4
Current Limiting Diode, 3.2V, SOD-80
Central Semi. Corp. CCLM3500
6
7
E1, E2, E3, E4, E5, E7, E8
Turret, Testpoint 0.063"
Mill-Max, 2308-2-00-80-00-00-07-0
7
4
J1, J2, J4, J5
Connector, Banana Jack
Keystone, 575-4
8
2
M1, M2
MOSFET N-Channel, 30V, D2PAK
Vishay, SUM85N03-06P-E3
9
2
R1, R2
Res., WSL 0.002 1W, 1%, 2512
Vishay, WSL25122L000FEA
10
1
R3
Res., Chip 30.1k, 0.1W 1%, 0805
Vishay, CRCW080530K1FKEA
11
2
R4, R6
Res., Chip 10k, 0.1W, 5%, 0805
Vishay, CRCW080510K0JNEA
12
0
R5, R7
Res., 0805
OPT
13
1
U1
I.C., Diode-OR Load Share Cont., DFN16DE-4 × 3
Linear Technology Corp., LTC4370CDE
dc1741af
4
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
GND
VINB
18V MAX
EN2
EN1
VCC
VINA
18V MAX
E8
J5
E7
J4
E5
E2
E3
E1
J1
1
1
R6
10K
R4
10K
R5
OPT
2
17
15
14
EN2
12
GATE1
4
6
50V
C2
0.039uF
VIN2
CPO2
3
7
8
9
10
2
3
THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
SCALE = NONE
DESCRIPTION
2ND PROTOTYPE
OFF2
D2 RED
D4
LN1251C-TR
CCLM3500
1
2 2
1
R2
0.002
1W 1%
2512
OFF1
D1 RED
D3
LN1251C-TR
CCLM3500
2 2
1
R1
0.002
1W 1%
2512
1
2
REV
5
E4
J2
OUTPUT
TECHNOLOGY
DATE:
N/A
SIZE
IC NO.
4
01/17/2012, 11:31 AM
DEMO CIRCUIT 1741A
LTC4370CDE
5
SHEET
1
OF
1
2
REV.
TWO-SUPPLY DIODE-OR CURRENT SHARING CONTROLLER
1630 McCarthy Blvd.
Milpitas, CA 95035
Phone: (408)432-1900 www.linear.com
Fax: (408)434-0507
LTC Confidential-For Customer Use Only
1. ALL RES ARE IN OHMS, 0805.
2. ALL CAP ARE IN MICROFARAD, 0805.
DATE
VLADIMIR O. 01-17-12
APPROVED
REVISION HISTORY
NOTES: UNLESS OTHERWISE SPECIFIED
_
ECO
4
TITLE: SCHEMATIC
CC
0.18uF
FETON2
FETON1
APPROVALS
M2
SUM85N03-06P
5
GATE2
COMP
OUT2
FETON2
FETON1
U1
OUT1
LTC4370CDE
RANGE
EP
GND
VCC
EN1
CUSTOMER NOTICE
RANGE
1
R3 30.1k
CVCC
0.1uF
16
13
VIN1
11
CPO1
50V
C1
0.039uF
M1
SUM85N03-06P
3
LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A
CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS;
HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO PCB DES.
KIM T.
VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL
APP ENG. VLADIMIR O.
APPLICATION. COMPONENT SUBSTITUTION AND PRINTED
CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT
PERFORMANCE OR RELIABILITY. CONTACT LINEAR
TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE.
R7
OPT
2
D
C
B
A
DEMO MANUAL DC1741A
SCHEMATIC DIAGRAM
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DEMO MANUAL DC1741A
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
dc1741af
6
Linear Technology Corporation
LT 0912 • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900
●
FAX: (408) 434-0507 ● www.linear.com
© LINEAR TECHNOLOGY CORPORATION 2012
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