Si85xx-TB UG
Si85XX U
The Si85xx products are unidirectional ac current sensors available with full scale current sense input ranges of 5,
10, and 20 A. Si85xx products are ideal upgrades for older current-sensing technologies offering size, performance
and cost advantages over current transformers, Hall Effect devices, DCR circuits, and other approaches. The
Si85xx are extremely low-loss, adding less than 1.3 mΩ of series resistance and less than 2 nH series inductance
in the sensing path at 25 ºC. Current-sensing terminals are isolated from the other package pins to a maximum
voltage of 1,000 VDC.
NIDIRECTIONAL
AC C
URRENT SENSOR TARGET BOARD USER’S GUIDE
1. Kit Contents
The Si85xx Unidirectional AC Current Sensor Development Kit contains the following items:
10 Amp Si8512 based evaluation board
Si85xx Unidirectional AC Current Sensor Target Board User's Guide (this document)
2. Hardware Overview
The Si85xx Target Board (Si85xx-TB, see Figure 1) provides a means to evaluate the ac current sensor in an
existing application. It is meant to be soldered directly into the users existing power supply. The board comes with
the Si8512 installed and provides a 10 Amp full scale input sense range and a 2.0 V full scale output voltage. For
more details on the Si8512, refer to the Si85xx Data Sheet.
Figure 1. Si85xx-TB Overview
Rev. 0.1 6/07 Copyright © 2007 by Silicon Laboratories Si85xx-TB UG
Si85xx-TB UG
3. Si85xx-TB Hardwired to Single-Phase POL
Figure 2 illustrates the Si85xx-TB soldered directly into a single-phase POL. The single phase POL was designed
to operate at a 400 kHz switch rate and provide better than 90 percent efficiency. It also provides 10 amps of peak
current to the load and protects the supply by shutting down in the event of an over current condition.
Figure 2. Si85xx-EVB Hardwired to Single-phase POL
Figure 3 illustrates the Si8512 accurately monitoring the POL's switching current. As shown in the scope plot, a
1.6 V peak output voltage accurately monitors the 8 Amp peak, 50 percent duty cycle, 400 kHz current signal of the
POL. A 20 mΩ sense resistor in series with the Si85xx is also monitored via a differential probe to provide a baseline measurement of the POL.
20 mΩ
Si8512
Sense Resistor
Figure 3. Si85xx-TB OUT1 Oscilloscope Plot
To accommodate this test, the Si85xx-TB was powered with a 5 V (100 mA) supply connected from J1 to J2. R1
was soldered from J4 to the respective phase control line of the POL. R2 and R4 were jumped to GND on J4. R3
was tied to 5 V and the Mode pin was jumped to VDD via J7.
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Si85xx-TB UG
4. Si85xx Evaluation Board
The Si85xx-TB has a Si8512 installed. Refer to Figure 4 for the locations of the various I/O connectors and major
components.
J1 5 V Supply Input power connection 5 V, 100 mA
J2 GND, Input Supply power return connection, 0 V
J3 HDR-2X2, Mode Control input
J4 HDR-2X07, R1, R2, R3, R4 inputs, OUT1, OUT2 outputs, and seven GND return pins
J5 IIN Positive Current Sense Input
J6 IOUT Negative/return Current Sense Input
J7 HEADER, TRST timing select jumper, default tied to VDD
Figure 4. Si85xx-TB Layout
4.1. VIN (J1, J2)
The user-provided power supply should be connected to connectors J1 and J2 where J2 is the reference. The
power source must be 5 V with at least 100 mA maximum output current.
Table 1. J1, J2 Pin Descriptions
Jumper # Description
J1 5 V, 100 mA
J2 GND
4.2. Mode Pin (J3)
Connector J3 is the Mode Control header. The user should tie this pin to either VDD or GND depending on their
power supply.
Table 2. J3 Pin Descriptions
Jumper # Description
J3 VDD or GND
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Si85xx-TB UG
4.3. R1, R2, R3, R4 Inputs, OUT1, OUT2 Outputs (J4)
Connector J4 is used to provide the control inputs (R1, R2, R3, R4, MODE) to the Si85xx. It also provides the
output voltage of the sensed input current on OUT1 and OUT2.
Table 3. J4 Pin Descriptions
Jumper # Description
J4 R1, R2, R3, R4, OUT1, OUT2, GND
4.4. IIN (J5)
Connector J5 is used to provide the positive current sense input to the Si85xx device.
Table 4. J5 Pin Descriptions
Jumper # Description
J5 IIN
4.5. IOUT (J6)
Connector J6 is used to provide the negative/return current sense input to the Si85xx device.
Table 5. J6 Pin Descriptions
Jumper # Description
J6 IOUT
4.6. TRST RESET (J7)
Connector J7 is used to set the timing for the Si85xx's integrator. J7 defaults to Reset option 1 where TRST is tied
VDD providing approximately 200 ns of reset time. Reset option 2 is selected by connecting a timing resistor (R1 in
Figure 4) from the TRST input to ground.
Table 6. J7 Pin Descriptions
Jumper # Description
J7 TRST – VDD or R1 to GND
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5. Schematic
V5V
C2
C1
0.1uFC20.1uF
10uFC110uF
Si85xx-TB UG
Normal Setup, No Mods
J5
IINJ5IIN
VDD
11
MODE
12
J6
IIOUTJ6IIOUT
10
IIN
9
IOUT
GND
8
R1
TRST
7
DNPR1DNP
V5V
Si851x
U1
U1
R11R2
2
MODE
R1
R2
R4
OUT1
R3
4
5
3
6
8
6
OUT2
OUT1R4R3
12
14
Si851x
OUT2
J7J7
1 2
V5V
Figure 5. Si85xx Target Board Schematic
J3J3
1 2
3 4
J2
GNDJ2GND
J4
1 2
3 457
9 10
HDR-2X07J4HDR-2X07
11
13
J15VJ1
5V
V5V
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Si85xx-TB UG
6. Bill of Materials
Table 7. Si825x Multi-Phase POL Reference Design Bill of Materials
Item Quantity Reference Part Number Manufacturer Description
1 1 C1 PCC2182CT-ND Digi-Key 10 uF
2 1 C2 PCC1812CT-ND Digi-Key 0.1 uF
3 1 J1 2551-2-00-44-00-00-07-0 Bisco 5 V
4 1 J2 2551-2-00-44-00-00-07-0 Bisco GND
5 1 J3 S2012-02-ND Digi-Key HDR-2X2
6 1 J4 S2012-07-ND Digi-Key HDR-2X07
7 1 J5 2551-2-00-44-00-00-07-0 Bisco IIN
8 1 J6 2551-2-00-44-00-00-07-0 Bisco IIOUT
9 1 J7 S1012-02-ND Digi-Key HEADER
10 1 R1 P150CCT-ND Digi-Key DNP
11 1 U1 Si8512-IS Digi-Key Si851x
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NOTES:
Si85xx-TB UG
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Si85xx-TB UG
CONTACT INFORMATION
Silicon Laboratories Inc.
400 West Cesar Chavez
Austin, TX 78701
Tel: 1+(512) 416-8500
Fax: 1+(512) 416-9669
Toll Free: 1+(877) 444-3032
Email: PowerProducts@silabs.com
Internet: www.silabs.com
The information in this document is believed to be accurate in all respects at the time of publication but is subject to change without notice.
Silicon Laboratories assumes no responsibility for errors and omissions, and disclaims responsibility for any consequences resulting from
the use of information included herein. Additionally, Silicon Laboratories assumes no responsibility for the functioning of undescribed features
or parameters. Silicon Laboratories reserves the right to make changes without further notice. Silicon Laboratories makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does Silicon Laboratories assume any liability
arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation consequential or incidental damages. Silicon Laboratories products are not designed, intended, or authorized for use in applications intended to
support or sustain life, or for any other application in which the failure of the Silicon Laboratories product could create a situation where personal injury or death may occur. Should Buyer purchase or use Silicon Laboratories products for any such unintended or unauthorized application, Buyer shall indemnify and hold Silicon Laboratories harmless against all claims and damages.
The sale of this product contains no licenses to Power-One’s intellectual property. Contact Power-One, Inc. for appropriate licenses.
Silicon Laboratories and Silicon Labs are trademarks of Silicon Laboratories Inc.
Other products or brandnames mentioned herein are trademarks or registered trademarks of their respective holders.
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