Linear DC2033A Quick setup guide

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dc2033af
DEMO MANUAL DC2033A
Description
LT6110
Cable/Wire
Drop Compensator
The DC2033A demo board features the LT
®
6110 cable/
wire drop compensator IC. The LT6110 is a precision
high side current sense that monitors load current via a
sense resistor and converts the sense voltage to a sink-
ing or sourcing current. Using the LT6110 sourcing or
sinking current to control a regulator’s output voltage can
compensate for the voltage loss due to a cable/wire drop.
The LT6110 includes an internal sense resistor or can be
used with an external sense resistor.
The DC2033A is jumper-configurable for the LT6110 to
use the internal sense resistor, an external 25mΩ sense
resistor,ora5.4mΩPCBtracesenseresistor.TheDC2033A
default configuration is for the LT6110 to use the internal
sense resistor.
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.
typical Wire Drop compensation connections
IOUT
+IN –IN
RIN
LT6110
V+
V–
RS
IMON
+
–
VIN
ILOAD ILOAD
IIOUT
RWIRE
(Ω)
VLOAD
CLOAD
DC2033 F01
FB
REGULATOR
LOAD
VREG
RFA
RFB
RG
IOUT
+IN –IN
RIN
LT6110
V+
V–
RS
IMON
+
–
VIN
ILOAD ILOAD
IIOUT
RWIRE
(Ω)
VLOAD
CLOAD
DC2033 F02
FB
REGULATOR
LOAD
+
–
RWIRE
(Ω)
VREG
RFA
RFB
RG
Figure 1. One Cable/Wire Compensation (One Wire to a Load Sharing the Regulator’s Ground)
Figure 2. Tw o Cable/Wire Compensation (One Wire to a Load and One Ground Return Wire)
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DEMO MANUAL DC2033A
Quick start setup
The Quick Start Setup of Figure 3, shows the basic con-
nections required for getting familiar with a DC2033A.
An ammeter is used to measure the load current to a 5Ω
load or an active load. To confirm the operation of the
LT6110, connect a wire jumper from VOUT1 to regulator.
This jumper connects the power supply 5V to the ROUT
100Ω pull-up resistor. The voltmeter across ROUT is for
monitoringthe IIOUT current. A DC2033Ais assembled with
a402Ω RIN1 resistor to provide quick testing convenience.
The RIN1 resistor and the VSENSE voltage set the LT6110
output current (IIOUT). To begin, adjust the power supply
for 1A load current. With 1A load current flowing through
the internal 20mΩ RSENSE resistor and 100µV VOS, the
IIOUT current is 50µA, (1A • 20mΩ + 100µV)/402Ω. The
voltmeter should read 5mV (50µA • 100Ω) ± the RSENSE,
VOS, RIN1, ROUT and IIOUT errors. Figure 4 shows the Quick
Setup schematic and IIOUT equations.
performance summary
Specifications are at TA= 25°C
PARAMETER MIN TYP MAX UNITS
Supply Range (V+to V–) 2 50 V
Amplifier Input Offset Voltage, VOS 100 300 µV
IOUT Current Error (Does Not Include VOS or RIN Errors) I+IN = 10µA
I+IN = 100µA
I+IN = 1mA
0.6
0.4
1.5
1.6
1
2.5
%
%
%
IMON Current Error (3 • I+IN) I+IN = 100µA 1.5 3 %
IOUT Voltage Range 0.4 V+V
IOUT Current Error Change for IOUT Voltage 0.4V to 3.5V 0.2 %/V
IMON Current Error Change for IMON Voltage 0V to 3.1V 0.2 %/V
IOUT Signal Bandwidth I+IN = 100µA 180 kHz
Supply Current 16 30 µA
Figure 3. Quick Start Setup
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DEMO MANUAL DC2033A
Quick start setup
Figure 4. DC2033A Quick Setup Circuit and Equations
Setting Up the DC2033A for Wire Compensation
Testing
The DC2033A default circuit uses the LT6110 internal
20mΩ sense resistor (RSENSE) and is configured with
0Ω RJ1, RJ2 and RJ3 are installed with 0Ω jumpers.
The RJ1 and RJ2 are standard 0Ω jumpers and con-
nect the LT6110 amplifier across the internal RSENSE.
The RJ1 and RJ2 resistance is not a concern as the
current flowing through them is very small (the resis-
tance variation of standard 0Ω resistors is 20mΩ to
100mΩ). However, a standard 0Ω jumper must not be
used in the path of the load current because the jumper's
I • R drop adds an error term to a wire drop compensation
design (for example the I • R drop of a 50mΩ jumper for
2A is 100mV). The RJ3 jumper is ultra-0Ω, with less than
1mΩ and rated for 30A at 70°C. The RJ3 jumper can be
removed and re-installed as RJ6 or RJ9, to configure the
DC2033A with an LT6110 and an external RSENSE (for an
alternative to an ultra-0Ω jumper install two 0.25 inch
length of 18AWG solid copper wires in parallel for up to
20A ILOAD).
The RIN1 resistor and the VSENSE voltage set the LT6110
output current (IIOUT) for regulator output voltage control.
The IIOUT current connects to the regulator feedback resis-
tors and boosts the regulator's output voltage (VREG). The
VREG voltage increases directly with the load current and
cancels the wire's I • R drop (VDROP) to the remote load.
A DC2033A has 0805 size pads for installing a switching
regulator's feedback resistors (RFA, RFB and RG). A low
quiescent current switching regulator has 10µA or less
current flowing through the feedback divider and requires
IOUT
+IN –IN
RIN1
402Ω
RJ10
0Ω
ROUT
100Ω
R1
1k
RJ1
0Ω
RJ2
0Ω
E4
GND
E2 5Ω LOAD
C2
0.1µF
LT6110
V+
V–
RS
IMON
+
–
GND
E3
E1 TO E5
WIRE JUMPER
REGULATOR
E1
ILOAD
1A
ILOAD
1A RJ3
0Ω
DC2033 F04
RSENSE
5V POWER
SUPPLY
IIOUT
E6
VOUT2
E7
IMON
E5
VOUT1
RMON
100Ω EB
3× IIOUT
IIOUT =VOUT1 −VOUT2
ROUT
IIOUT =ILOAD •RSENSE +VOS
RIN1
ROUT =100
RIN1 =402
TYPICAL VOS =100µV
RSENSE =20mΩ, ±15%
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DEMO MANUAL DC2033A
three feedback resistors for an LT6110 connection, as
in Figure 1. In addition, a DC2033A includes pads for a
feedback loop compensation capacitor, C4.
A Quick Design Guide.
Variable Definitions:
ILOAD is the maximum load current and IIOUT is the LT6110
output current, (design target is 100µA).
RSENSE is the LT6110 internal or external current sense
resistor and RWIRE is the copper wire resistance.
(RWIRE includes the resistance of the load current car-
rying PCB traces and wire connectors minus the RSENSE
resistance).
VFB is the regulator's feedback reference voltage.
IQis the no-load quiescent current flowing through the
resistor feedback divider, (IQ= VFB/RG), (refer to the
regulator’s demo manual).
Quick start setup
VREG is the no-load current regulator output voltage.
Quick Design Equations:
RIN1 =
V
SENSE
IIOUT
VSENSE =ILOAD•RSENSE
RFA =VDROP
IIOUT
VDROP =ILOAD•(RSENSE +RWIRE)
RFB =VREG – VFB
IQ
RG=VFB
IQ
Quick Design Check:
V
REG
=(R
FA
+R
FB
+R
G
)•I
Q
NOTE: For DC2033A REGULATOR input voltages higher
than 36V, remove the RJ10 jumper sorting the 27V Zener,
D1. Refer to the LT6110 data sheet for additional applica-
tion circuits and information.
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DEMO MANUAL DC2033A
applications
DC2033A Application Options
The DC2033A is designed to be used with a regulator
board and copper wire. On board jumper pads and turrets
configure an LT6110 circuit using 0Ω jumpers and provide
for wired connections to a regulator board. Figures 6, 7
and 8 show typical DC2033 application circuit options.
Table 2. DC2033A Current Sense Resistor, RSENSE and Jumper
Options
RSENSE RESISTANCE (25°C)
JUMPERS
STANDARD 0Ω
JUMPERS
ULTRA-0Ω ILOADMAX
Internal 20mΩ at ILOAD = 1A,
(16.5mΩ to 22.5mΩ
RJ1, RJ2 RJ3 3A at 125°C
LT6110
RSENSE
22mΩ at ILOAD = 3A,
(18.5mΩ to 24.5mΩ
External
REXT
25mΩ at ILOAD = 1A,
±1%
RJ4, RJ5 RJ6 6A at 70°C
5A at 90°C
External
RPCB
5.4mΩ at ILOAD = 1A,
±15%
5.7mΩ at ILOAD = 10A,
±15%
RJ7, RJ8 RJ9 20A at 25°C
10A at 90°C
The DC2033A with a Regulator Demo Board
A DC2033A board can be configured and connected to a
regulator demo board for a complete cable/wire drop com-
pensation system evaluation. Typically a regulator demo
board includes a feedback resistor divider that sets the
output voltage VREG. Remove the feedback resistors from
theregulatorboardandconnecttheregulator’sfeedbackpin
(FB or VREF) to the DC2033A VFB (E9). In addition, connect
theVOUT andGNDoftheregulatorboardto the REGULATOR
(E1) and to the GND (E3) of the DC2033A respectively.
Figure 5 shows Linear Technology’s buck regulator demo
board, DC1458A, connected to a DC2033A, using an
external sense resistor, REXT. The DC1458A demo board
includes the LT3972, 5V at 3.5A buck regulator. Figure 6
shows the complete cable/wire compensation schematic.
NOTE: The LT3972 R2 and R3 feedback resistors are re-
moved from the DC1458A board and are on the DC2033A
board (RFA, RFB and RG). The no-load LT3972 voltage is
Figure 5. DC1458A and DC2033A Connections
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DEMO MANUAL DC2033A
applications
Figure 6. An LT3972 5V at 3.5A Buck Regulator with LT6110 Circuit Compensating for the Drop of a 10ft, 24AWG Cable/Wire
IOUT
RFA, RFB and RG VALUES ARE FOR COMPENSATION OF 10ft, 24AWG WIRE AND 5V AT 3.5A LOAD. +IN –IN
RIN
866Ω
RJ10
0Ω
ROUT
100Ω
R1
1k
RJ4
0Ω
RJ5
0Ω E4
GND
E2
LOAD
C2
0.1µF
LT6110
V+
V–
RS
IMON
+
–
E3
GND
E1
REGULATOR
E6
GND
E5
VOUT
5V AT 3.5A
ILOAD
3.5A
ILOAD
3.5A RJ6
0Ω
DC2033 F06
RSENSE
RWIRE
24AWG
10ft
0.25Ω
REXT
25mΩ
IIOUT
E6
VOUT2 E7
IMON
E5
VOUT1
RMON
100Ω
EB
3× IIOUT
E3
GND
E9
SYNC
E9
VFB
E7
PGOOD
LOAD
47µF
VLOAD
5V
3.5A
RFA 9.53k RFB 523k RG 100k
C4
47pF
C5 0.1µF
C4 47µF
R2 R2 AND R3 ARE
REMOVED.
DC1458 TO DC2033 CONNECTIONS.
R3
C6 1000pF
JP2
1 2 3
BURST MODE
SYNC ON
R4 100k
R5 15k
C8 100pF
LT3972 BUCK REGULATOR
R1
63.4k
C1
0.47µF
D1
MBRA340T3
L1
6.8µH
C3 4.7µF
C2 22µF
BD BOOST SW VIN RUN/SS
RT
VC
FB
PGOOD
SYNC
LT3972EMSE
GND
JP1
R6
100k
1 2 3 4
RUN
SHDN
EXTSS
+
C7 0.22µF
E1
VIN
E8
GND
E2
GND
E4
EXTSS
DC1458A
LT6110 WIRE DROP COMPENSATOR
DC2033A
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DEMO MANUAL DC2033A
applications
5V and the feedback voltage, VFB is 0.79V. The values of
the feedback resistors are selected using the Quick Design
Guide with an IQ= 8µA. The specified quiescent current is
8µA. Resistors RFA, RFB and RGare 9.53k, 523k and 100k
respectively. VREG = (9.53k+ 523k+ 100k) • 8µA= 5V
(±1% and ±1.27% resistor and VFB tolerance respectively).
The DC2033A PCB Trace RSENSE
A DC2033A has a serpentine PCB trace that can be used as
an LT6110 external sense resistor for high load currents
(5A to 20A). Remove RJ3 ultra-0Ω jumper and install as
RJ9.Remove standard 0Ω jumpers RJ1 andRJ2 and install
Figure 7. DC2033 Configured for RPCB (PCB Trace Sense Resistor)
RJ7 and RJ8. Figure 7 shows the DC2033A schematic with
LT6110 and PCB RSENSE.
The copper thickness of a DC2033A PCB trace is two
ounces. A typical resistance for a 2oz square trace is
0.25mΩ at 25°C. The RPCB serpentine trace length is six
0.15 × 0.6 inch rectangular traces connected by 0.015 ×
0.15 inch traces. The current path area of each rectangu-
lar trace is equivalent to three and one-half squares. The
RPCB resistance is 5.4mΩ at 25°C, ±15%. RWIRE is the
total resistance from the regulator output to the remote
load (minus the RSENSE resistance).
IOUT
+IN –IN
RIN1
RJ10
0Ω
ROUT
100Ω
R1
1k
RJ7
0Ω
RJ8
0Ω E4
GND
E2
LOAD
C2
0.1µF
LT6110
V+
V–
RS
IMON
+
–
E3
GND
E1
REGULATOR
DC2033A
ILOAD
ILOAD RJ9
0Ω
DC2033 F07
RSENSE
RWIRE (WIRE RESISTANCES)
*RPCB
5.4mΩ
±15%
IIOUT
E6
VOUT2 E7
IMON
E5
VOUT1
RMON
100Ω
EB
3× IIOUT
E9
VFB
LOAD
*RPCB
CLOAD
VLOAD
RFA
RFB
RG
C4
REGULATOR
VREG
FB
VIN
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DEMO MANUAL DC2033A
applications
The RJ9 jumper in the load current path must be ultra-0Ω,
1mΩ or less (the jumper's I • R drop adds an error term
to a wire drop compensation design). The RJ3 jumper is
ultra-0Ω, less than 1mΩ and can be removed and installed
as RJ9 (for an alternative to an ultra-0Ω jumper install two
0.25 inch length of 18AWG solid copper wires in parallel
for an RJ9 jumper).
Using the DC2033A with an LT6110 DFN Package
The bottom layer of a DC2033A is designed for an LT6110
DFN IC. To use a DC2033A for evaluating with an LT6110
DFN IC with an internal RSENSE requires the following:
Remove U1 (LT6110 SOT IC) and jumper RJ3 from the top
of the board. Install a U2 (LT6110 DFN), RJ11 and RJ12
on the bottom of DC2033A. Figure 8 shows the schematic
of a DC2033A with an LT6110 DFN package.
The DC2033A PCB layout is optimized for an LT6110
SOT23 package. A DC2033A with a LT6110 DFN (U2)
and an internal RSENSE, adds a 2% RSENSE error due to a
PCB via from the top to the bottom PCB layer. In addition
to using a DC2033A with a LT6110 DFN and an internal
RSENSE, the DC2033A can be configured for an LT6110
DFN with an external REXT or RPCB current sense resistor
(refer to the jumper table on the DC2033A schematic).
The load current path RJ6, RJ9, RJ11 and RJ12 jumpers
must be ultra-0Ω, less than 1mΩ, (for an alternative to
an ultra-0Ω jumper install two 0.25 inch length of 18AWG
solid copper wires in parallel for an RJ6, RJ9, RJ11 or
RJ12 jumper).
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DEMO MANUAL DC2033A
Figure 8. DC2033 Configure with an LT6110 DFN Package and Internal RSENSE
applications
IOUT
+IN –IN
RIN1
RJ10
0Ω
ROUT
100Ω
R1
1k
RJ1
0Ω
RJ2
0Ω
E4
GND
E2
LOAD
C2
0.1µF
LT6110
V+
V–
RS
IMON
+
–
E3
GND
E1
REGULATOR
DC2033A
ILOAD
ILOAD RJ12
0Ω
DC2033 F08
RSENSE
RJ11
0Ω
RWIRE
0Ω
E3
GND
E1
REGULATOR
IIOUT
E6
VOUT2 E7
IMON
E5
VOUT1
RMON
100Ω
EB
3× IIOUT
E9
VFB
LOAD
CLOAD
VLOAD
RFA
RFB
RG
C4
REGULATOR
VREG
FB
VIN
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DEMO MANUAL DC2033A
parts list
ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER
1 0 C1, C4 CAP, X7R, 50V, 10%, 0603 OPT
2 1 C2 CAP, X7R, 0.1µF, 50V, 10%, 0603 TDK C1608X7R1H104K
3 0 C3 CAP, X7R, 50V,1206 OPT
4 1 D1 DIODE, ZENER 27V 200MW SOD-323 DIODES/ZETEX, BZT52C27S-7-F
5 4 E5, E6, E7, E9 TESTPOINT, TURRET, 0.063" MILL-MAX, 2308-2-00-80-00-00-07-0
6 5 E1 TO E4, E8 TESTPOINT, TURRET, 0.093" MILL-MAX, 2501-2-00-80-00-00-07-0
7 1 REXT CURRENT SENSE RESISTOR 0.025Ω 1% 2512 VISHAY, WSL2512R0250FEA18
8 0 RIN2, RG, RFA, RFB RES, CHIP, 1%, 1/8W, 0805 OPT
9 1 RIN1 RES, CHIP, 1%, 1/8W, 402Ω, 0805 VISHAY, CRCW0805402RFKEA
10 3 RJ1, RJ2, RJ10 RES, 0Ω JUMPER, 0805 VISHAY, CRCW08050000Z0EA
11 0 RJ4, RJ5, RJ7, RJ8 RES, 0Ω JUMPER, 0805 OPT
12 1 RJ3 RES, ULTRA-0Ω JUMPER, 2512 NACOMA/TEPRO RN5326
13 0 RJ6, RJ9, RJ11, RJ12 RES, ULTRA-0Ω JUMPER, 2512 OPT USE TWO 0.25in,18AWG SOLID COPPER WIRES IN
PARALLEL
14 2 ROUT, RMON RES, CHIP, 1%, 1/8W, 100Ω, 0805 VISHAY, CRCW0805100RFKEA
15 0 RPCB RES PCB TRACE, 5.4mΩ, ±15% (PCB TRACE RESISTOR)
16 1 R1 RES, CHIP, 1%, 1/8W, 1k, 0805 VISHAY, CRCW08051K00FKEA
17 1 U1 IC, WIRE DROP COMPENSATOR, TSOT-23-8 LINEAR TECHNOLOGY, LT6110ITS8#PBF
18 0 U2 IC, WIRE DROP COMPENSATOR, 8 LEAD DFN, OPT
19 4 MH1, MH2, MH3, MH4 STANDOFF, SNAP ON KEYSTONE, 8831
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