Document 385-1
SMT Current Sensors – CST Series
The CST surface mount current sensing transformers
are designed for use from 50 kHz to nearly 1 MHz to
sense continuous currents to 10 Amps and greater.
The CST1 and CST2 differ in pinout numbering and layout
in order to meet the requirements of different applications.
These transformers feature very low DC resistance and
500 V isolation between windings. They are available
in eight different turns ratios to meet a wide variety of
requirements. They are ideal for use in switching power
supply applications.
Coilcraft
Designer’s Kit C189
contains samples of each
of the standard parts shown. To order, contact Coilcraft
or visit
http://order.coilcraft.com.
Part number
1
CST1
CST2
CST1-020X_
CST1-030X_
CST1-040X_
CST1-050X_
CST1-060X_
CST1-070X_
CST1-100X_
CST1-125X_
CST2-020X_
CST2-030X_
CST2-040X_
CST2-050X_
CST2-060X_
CST2-070X_
CST2-100X_
CST2-125X_
Turns ratio
pri : sec
1
:
20
1
:
30
1
:
40
1
:
50
1
:
60
1
:
70
1
:
100
1
:
125
Inductance
2
min (µH)
81.0
180.0
320.0
500.0
730.0
980.0
2000.0
3000.0
Primary Terminating
DCR max (Ohms) current
3
resistor
4
Primary Secondary
(A)
(Ohms)
0.006
0.006
0.006
0.006
0.006
0.006
0.006
0.006
0.400
0.870
1.140
1.500
1.980
4.750
5.500
6.500
10
10
10
10
10
10
10
10
2.0
3.0
4.0
5.0
6.0
7.0
10.0
12.5
Volt-time
product
5
(V-µsec)
16
24
32
41
49
57
81
101
Color
dot
Red
Orange
Yellow
Green
Blue
Violet
Gray
Black
1. When ordering, please specify
packaging
code:
CSTX-125XC
Packaging: C
= 7″ machine-ready reel. EIA-481 embossed plastic
tape (250 parts per full reel).
B
= Less than full reel. In tape, but not machine ready.
To have a leader and trailer added ($25 charge), use
code letter C instead.
D
= 13″ machine-ready reel. EIA-481 embossed plastic
tape (1000 parts per full reel).
Inductance measured between secondary pins at 100 kHz, 0.1 Vrms.
Primary current of 10 A causes approximately 25°C temperature
rise above 25°C ambient. Higher current causes a greater tempera-
ture rise (see Temperature Rise vs Current curve).
Terminating resistor value is based on 1 Volt output with 10 Amps
flowing through the primary. To determine the value for other input
currents, refer to the schematic and use the following formula:
R
T
( ) = V
ref
*
N
sec
/
I
pri.
Volt-time product is a maximum value for the secondary.
Storage and operating temperature range -40°C to +85°C.
Electrical specifications at 25°C.
Schematics
CST1
8
6
Current
I
pri
Pri
(1 turn)
Sec
(N turns)
Terminating
resistor (R
T
)
V
ref
2.
3.
7
4
4.
CST2
8
1
5.
6.
7.
Current
I
pri
Pri
(1 turn)
Sec
(N turns)
Terminating
resistor (R
T
)
V
ref
7
3
Specifications subject to change without notice.
Please check our website for latest information.
Document 385-1
Revised 10/21/04
Document 385-2
CST Series Current Sensors
Temperature Rise vs Current
80
Pinouts
CST1
8
3
CST2
7
4
3
Temperature rise (from 25°C)
70
60
50
40
30
20
10
0
0
2
4
6
8
10
12
14
16
18
20
4
1
6
1
6
7
8
Bottom View
Bottom View
Current (A rms)
Dimensions
0.230
5,84
Color dot by
pin 1 indicates
part number
0.240
6,10
0.209
max
5,3
0.004 / 0,10
0.315
max
8,0
0.320
max
8,13
Recommended Land Pattern
0.118
3,0
0.023 ±0.008
0,6 ±0,2
0.098
2,5
0.073 ±0.008
1,85 ±0,2
0.106
2,7
0.047
1,2
0.063
1,6
0.073
1,85
0.079 ±0.008
2,0 ±0,2
0.051
1,3
0.051
1,3
Tape and reel:
250/7″ reel; 1000/13″ reel 16 mm tape width
For packaging data see Tape and Reel Specifications section.
Specifications subject to change without notice.
Please check our website for latest information.
Document 385-2
Revised 01/12/05
Analogue and Mixed Signal
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