How does it work?
Analogue to digital conversion is performed by an integrated sigma-delta modulator, giving a one-bit serial bitstream output.
- Digital output from a sigma-delta modulator
- 12-bit effective resolution with 20kHz bandwidth
- 10MHz clock frequency
- Additional over-current detection output
HLSR 40-PW and HO 80 digital output current transducers
Why digital output?
Digital output allows the user to choose the filter used on the bitstream to optimise the balance between resolution and response time. Digital outputs are also immune to noise. A single-bit output minimises the connections required, ensuring that the transducers are highly compact.
Digital output formats
- Single-bit output two wire CMOS (with clock in or out modes)
- RS422 Manchester
- LVDS Manchester
- Four-wire mode according to the LVDS or RS 422 (Clock in or out) standards.
Different filters on the same bitstream
Several different filters may be used on a given bitstream. A sinc3 filter is used with an over-sampling ratio of 128, the effective resolution of a 50A sensor is 12 bits, and the response time is 38µs. A sinc2 filter with an over-sampling ratio of 16 would give a response time of 4.6µs from the same bitstream, but the resolution would be reduced to 6 bits.
Response time to over-current
Transducers in the HO family have an over-current detect (OCD) feature, which measures the current level before the A/D converter with a response time of 2µs.
Same footprints as existing sensors and same footprints as the analogue HLSR. HO-NPW, HO-PW and HO-SW models.
Configurations
Users can have single-ended and Manchester modes with two extra pins, so clock and data may transmit differential signals to meet RS422 and LVDS standards.
To allow a single clock to be used throughout the system, the transducer clock may be configured as an input in the range 5MHz–12.5MHz.
Voltage range and operating temperature
The new transducers can use a supply voltage of 3.3V or 5V. The operating temperature range is from -40°C to +105°C.
About LEM
LEM manufactures market-leading current and voltage transducers used in demanding applications such as drives, welding, renewable energy, power supplies, traction, high precision and automotive. LEM has production locations in Beijing (China), Geneva (Switzerland), Machida (Japan) and Sofia (Bulgaria).
