CT04 Series

Low-Profile SMT Current Sense Transformers

The CT04 Series is a low-profile SMT current sense transformer designed for compact, high-density power designs requiring accurate, isolated current measurement. With a maximum height of just 4.10 mm and a 6.9 × 8.13 mm footprint, it delivers reliable sensing performance in space-constrained DC/DC, AC/DC, and POL converter layouts. Turns ratios from 1:50 to 1:125 enable flexible scaling for controller input requirements while maintaining repeatable signal integrity.

Engineered for modern SMPS architectures, the CT04 Series supports switching-frequency applications up to approximately 1 MHz, depending on the specific part number. Its 500 VAC isolation rating, robust –40 °C to +130 °C temperature capability, and SMT construction optimized for automated reflow assembly ensure consistent performance across industrial, telecom, and distributed-power environments.

Key Features

Low-profile SMT current-sense transformer (4.10 mm height)
Compact 6.9 mm × 8.13 mm PCB footprint
Supports primary currents up to 20 A
Supports SMPS switching frequencies up to ~1.5 MHz
Turns ratios from 1:50 to 1:125
500 VAC Hi-Pot tested primary-to-secondary isolation
Operating temperature range: –40 °C to +130 °C
Reflow-ready SMT design with tape-and-reel packaging
Suitable for pick-and-place assembly

APPLICATIONS

DC/DC converters for industrial, telecom, and embedded systems
AC/DC power supplies and front-end conversion stages
POL (Point-of-Load) regulators requiring precise inductor current sensing
Feedback and current-mode control loops in switching power supplies
Overload, short-circuit, and protection monitoring circuits
Distributed power systems and board-level current measurement

Electrical Specifications @ 25°C - Operating Temperature Range¹: -40°C to +130°C

Part Number

Turns Ratio
(TR)

Secondary Inductance² (μH,Min)

Secondary DCR (Ω,Max)

Current Rating⁴ (A,Max)

SRF⁵ (6-4) (MHz,Typ)

ET Product⁸
(V-μs, Max)

Hi Pot (V_AC)

CT04-050

1:50

352

0.9

2.5

500

View

CT04-070

1:70

690

1.7

1.5

500

View

CT04-100

1:100

1400

3.0

1.0

130

500

View

CT04-125

1:125

2200

5.0

1.0

160

500

View

Part Number

ET Product⁸
(V-μs, Max)

CT04-050

View

CT04-070

View

CT04-100

130

View

CT04-125

160

View

Mechanical Drawing

Recommended PCB Layout

Schematic

1.
Operating Temp. Range: The combination of ambient temperature and temperature rise.
2.
Secondary Inductance: Tested at 10kHz, 1V_RMS.
3.
Primary DCR (8-7): 0.4 mΩ (Ref)
4.
Current Rating: Peak current (50% duty cycle) through primary (8-7) to cause 40°C temperature rise at 25°C ambient.
5.
SRF: Values are for reference only.
6.
Flammability Standard: Meets UL 94V-0.
7.
Terminating Resistor (RB): To calculate the value use the formula,
R_B = E_OTR/I_P
8.
ET Product: The maximum ET is based upon a flux density of 3700 Gauss at 25°C. Suitable for bipolar applications only.

ET = E_O/2f
E_O = I_PR_B/TR

Whereas,

E_O = Output voltage (V) TR = Turns Ratio
R_B = Term. Resistor (Ω) f = Frequency (Hz)
I_P = Primary Current (A)
9.
PACKAGING
- Reel Diameter: 13”
- Reel Width: 16mm
- Pieces/Reel: 1200

Specifications subject to change without prior notice.

CT04 Series

Low-Profile SMT Current Sense Transformers

Key Features

APPLICATIONS

Electrical Specifications @ 25°C - Operating Temperature Range1: -40°C to +130°C

Part Number

Turns Ratio (TR)

Secondary Inductance2 (μH,Min)

Secondary DCR (Ω,Max)

Current Rating4 (A,Max)

SRF5 (6-4) (MHz,Typ)

ET Product8 (V-μs, Max)

Hi Pot (VAC)

Part Number

ET Product8 (V-μs, Max)

Mechanical Drawing

Recommended PCB Layout

Schematic

Electrical Specifications @ 25°C - Operating Temperature Range¹: -40°C to +130°C

Turns Ratio
(TR)

Secondary Inductance² (μH,Min)

Current Rating⁴ (A,Max)

SRF⁵ (6-4) (MHz,Typ)

ET Product⁸
(V-μs, Max)

Hi Pot (V_AC)

ET Product⁸
(V-μs, Max)