Si85xx Ta rget Board User ’s Guide
Si85
X X
U
NIDIRECTIONAL
AC C
URRENT
S
ENSOR
T
ARGET
B
OARD
U
SER
’
S
G
UIDE
1. Introduction
The Si85xx products are unidirectional ac current sensors available with full-scale current sense input ranges of 5,
10, and 20 Amps. 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 m of series resistance and less than 2 nH
series inductance in the sensing path at 25 °C. Current-sensing terminals are isolated from the other package pins,
providing 1000 V
RMS
of isolation with the 4x4x1 mm QFN package and 5000 V
RMS
of isolation with the wide-body,
20-pin SOIC package.
2. Kit Contents
The Si85xx Unidirectional AC Current Sensor Development Kit contains one of two versions of the 10 Amp,
Si8512-based evaluation board or one version of the 20 Amp Si8513 based evaluation board. See "8. Ordering
Guide" on page 10 for part number details for the 1 kV (QFN) or 5 kV (SOIC).
3. Hardware Overview
The Si85xx Target Boards shown in Figures 1, 2, and 3 provide a means of evaluating the ac current sensor in an
existing application. The boards are meant to be soldered directly into a user’s existing power supply and come
with either the Si8512 installed (10 Amp full-scale input range) or with the Si8513 installed (20 Amp full-scale input
range). For more information, refer to the Si85xx data sheet.
Figure 1. Si85xx-TB Overview (1 kV, 10 Amp Target Board)
Figure 2. Si85xx5kV-TB Overview (5 kV, 10 Amp Target Board)
Figure 3. Si85xx20AQFN-TB Overview (1 kV, 20 Amp Target Board)
Rev. 0.4 8/10
Copyright © 2010 by Silicon Laboratories
Si85xx Target Board User’s Guide
Si85xx Ta rget Board User ’s Guide
4. Target Board Hardwired to Single-Phase POL
Figure 4 illustrates the Si85xx-TB (1 kV, 10 Amp target board) soldered directly into a single-phase POL. The
single-phase POL is designed to operate at a 400 kHz switch rate and provides 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
overcurrent condition.
Figure 4. Si85xx-EVB Hardwired to Single-Phase POL (1 kV Target Board)
Figure 5 shows 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 m sense resistor in series with the Si85xx is also monitored via a differential probe to provide a baseline
measurement of the POL.
20 m
Sense Resistor
Si8512
Figure 5. 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 V
DD
via J7.
2
Rev. 0.4
Si85xx Ta rget Board User ’s Guide
5. Si85xx Evaluation Board
The boards come with either the Si8512 installed (10 Amp full-scale input range) or with the Si8513 installed
(20 Amp full-scale input range). Refer to Figures 6, 7, and 8 for the locations of the various I/O connectors and
major components. Note that 100
resistors were added in series to the R1 to R4 control lines on the 5 kV,
10 Amp target board and to the 20 Amp QFN target board to reduce inductive ringing from excessively long wires;
these are optional for the end-system design.
J1
J2
J3
J4
J5
J6
J7
5 V Supply Input power connection 5 V, 100 mA
GND, Input Supply power return connection, 0 V
HDR-2X2, Mode Control input
HDR-2X7, R1, R2, R3, R4 inputs, OUT1, OUT2 outputs, and seven GND return pins
IIN Positive Current Sense Input
IOUT Negative/return Current Sense Input
HEADER, TRST timing select jumper, default tied to VDD
Figure 6. Final Setup (1 kV, 10 Amp Target Board)
Figure 7. Final Setup (5 kV, 10 Amp Target Board)
Figure 8. Final Setup (1 kV, 20 Amp Target Board)
Rev. 0.4
3
Si85xx Ta rget Board User ’s Guide
5.1. 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 provide up to 5 V with at least 100 mA output current.
Table 1. J1, J2 Pin Descriptions
Jumper #
J1
J2
Description
5 V, 100 mA
GND
5.2. Mode Pin (J3)
Connector J3 is the Mode Control header. The user should tie this pin to either VDD or GND depending on the
power supply topology being tested.
Table 2. J3 Pin Descriptions
Jumper #
J3
Description
VDD or GND
5.3. 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 #
J4
Description
R1, R2, R3, R4, OUT1, OUT2, GND
5.4. IIN (J5)
Connector J5 is used to provide the positive current sense input to the Si85xx device.
Table 4. J5 Pin Descriptions
Jumper #
J5
Description
IIN
5.5. IOUT (J6)
Connector J6 is used to provide the negative/return current sense input to the Si85xx device.
Table 5. J6 Pin Descriptions
Jumper #
J6
Description
IOUT
5.6. TRST RESET (J7)
Connector J7 is used to set the timing for the Si85xx 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
Figures 9 and 10 and R7 in Figure 11) from the TRST input to ground.
Table 6. J7 Pin Descriptions
Jumper #
J7
Description
TRST—VDD or R1 to GND
4
Rev. 0.4
V5V
J3
V5V
2
4
1
3
J2
C1
10uF
C2
0.1uF
J1
5V
GND
6. Schematics
V5V
U1
VDD
J5
IIN
IIN
R2
R3
R4
OUT1
TRST
GND
OUT2
IOUT
9
J6
IIOUT
Normal Setup, No Mods
10
12
7
MODE
11
R1
DNP
8
J4
1
R1
2
3
4
5
6
HDR-2X07
2
4
6
8
10
12
14
MODE
R1
R2
R3
R4
OUT1
OUT2
1
3
5
7
9
11
13
Si851x
Si85xx Ta rget Board User ’s Guide
Figure 9. Si85xx-TB Target Board Schematic (1 kV, 10 Amp Target Board)
1
Rev. 0.4
2
J7
V5V
5
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