SI8513-C-IS Datasheet, PDF (9/37 Pages) List of Unclassifed Manufacturers – Si85XX UNIDIRECTIONAL AC CURRENT SENSORS

Si85xx
2. Functional Overview
The Si85xx ac current sensor family of products mimics
the functionality of traditional current transformer (CT)
circuits with burden resistor, diode, and output filter, but
offers enhanced performance and added capabilities.
These devices use inductive current sensing and on-
board signal conditioning electronics to generate a 2 V
full-scale output signal proportional to the ac current
flowing from the IIN to the IOUT terminals. As shown in
Figures 2 and 3, current flowing through the metal
package slug induces a signal in the pickup coil on the
Si85xx die. This signal is applied to the input of an
integrator that reconstructs the ac current flowing from
IIN to IOUT. Onboard circuitry provides cycle-by-cycle
integrator reset and temperature and offset voltage
compensation to achieve initial measurement accuracy
to within ±5%.
IIN
R1 R2
Si850x
RESET LOGIC
VDD2
INTEGRATOR
PICKUP
COIL
SIGNAL CONDITIONING
OUT
TEMP
SENSOR
ADC
AUTO CALIBRATION
LOGIC
NC
IOUT
GND2 GND1 VDD1
GND3
TRST
Figure 2. Si850x (Single Output) Block Diagram
IIN
R1 R2 R3 R4
Si851x
RESET LOGIC
MODE LOGIC
MODE
INTEGRATOR
PICKUP
COIL
SIGNAL CONDITIONING
OUT1
OUT2
TEMP
SENSOR
ADC
AUTO CALIBRATION
LOGIC
IOUT
GND
VDD
TRST/FAULT
Figure 3. Si851x (Ping Pong Output) Block
Diagram
The Si85xx is superior to other current sensing
approaches and benefits the system in a number of
ways:
 Small size: With its 4x4 mm footprint and 1 mm
height (QFN package option), the Si85xx is among
the smallest current sensors available.
 Large output signal: The nominal 2.0 V full-scale
output swing offers superior noise immunity versus
other current sensing technologies.
 Low loss: The Si85xx adds only 1.3 m (at 25 °C)
to the sensing path, making it one of the lowest-loss
current sensors available. Low 2 nH primary series
inductance is 2,000 times lower compared to a CT
and results in significantly less ringing.
 High precision: All versions are available with an
initial maximum error of ±5% of reading; one of the
most accurate current sensors available.
 Ping-Pong output mode (Si851x): Alternately
routes the current measurements from each side of
a full-bridge circuit to separate output pins for
comparison, which is very useful for transformer flux
balancing applications. Eliminates a second CT in a
full-bridge application.
 Leading edge noise suppression: Filters out
reflected noise due to long reverse recovery time of
output rectifier. Eliminates the need for external
leading edge blanking circuit.
 High common-mode voltage: The Si85xx offers a
minimum of 1,000 V_RMS (for QFN package) or
5 kV_RMS (for SOIC package) of common-mode
voltage range (or isolation), making it useful over a
very wide voltage range.
Preliminary Rev. 0.4
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