ACS726 Galvanically Isolated Current Sensor IC With Differential Output and Externally Adjustable Gain FEATURES AND BENEFITS DESCRIPTION Fully differential architecture for improved immunity to The Allegro ACS726 current sensor IC family provides offset drift and common mode noise economical and precise solutions for AC current sensing in Spare differential back end amplifier for externally industrial, commercial, and communications systems. The adjustable gain and bandwidth using simple RC networks device package allows for easy implementation by the customer. Greatly improved bandwidth through proprietary Typical applications include motor control, load detection and amplifier and filter design techniques management, switched-mode power supplies, and overcurrent High bandwidth 120 kHz analog output fault protection. Patented integrated digital temperature compensation The fully differential output gives superior immunity to output circuitry allows nearly closed-loop accuracy, through offset drift as well common mode noise. entire temperature range, in an open loop sensor 1.1mprimaryconductorresistanceforlowpowerloss ACS726 is the first current sensor IC to include a fully and high inrush current withstanding capability differential back-end amplifier (BEA) that can be used to adjust Small footprint, low-profile QSOP24 package suitable gain and bandwidth via external RC networks. The BEA is for space-constrained applications fully independent and when unused, it can be powered down Integrated shield virtually eliminates capacitive coupling to reduce power consumption. from current conductor to die due to high dV/dt voltage The device consists of a precise, low-offset, linear Hall transients sensor circuit with a copper conduction path located near the Continued on the next page surface of the die. Applied current flowing through this copper conduction path generates a magnetic field which is sensed Package: 24-pin QSOP (suffix LF) by the integrated Hall IC and converted into a proportional voltage. Device accuracy is optimized through the close proximity of the magnetic field to the Hall transducer. A Continued on the next page Approximate scale 3.3 V 24 1 NC IP+ 23 2 NC IP+ 22 3 VCC IP+ 21 C BYPASS 4 VOUTGP IP+ 20 0.1 F 5 VOUTGN IP+ 6 IP+ ACS726 R R FB1 FB2 19 VINGN I P 18 VINGP IP R R IN1 IN2 7 IP 17 8 VOUTP IP 16 9 VOUTN IP 15 10 GND IP 14 11 NC IP 13 12 NC Typical Application Current sensor IC gain can be set using R and R FB IN ACS726-DS, Rev. 1Galvanically Isolated Current Sensor IC ACS726 With Differential Output and Externally Adjustable Gain Features and Benefits (continued) Description (continued) 3 to 3.6 V, single supply operation precise, proportional voltage is provided by the low-offset, chopper- Factory-trimmed sensitivity and quiescent output voltage for stabilized BiCMOS Hall IC, which is programmed for accuracy improved accuracy after packaging. The output of the device has a positive differential Chopper stabilization results in extremely stable quiescent voltage ( V V ) when an increasing current flows through OUTP OUTN output voltage the primary copper conduction path (from pins 1 through 6, to pins Ratiometric output from supply voltage 7 through 12), which is the path used for current sensing. The internal resistanceofthisconductivepathis1.1mtypical,providinglow power loss. The terminals of the conductive path are electrically isolated from the sensor IC signal leads (pins 13 through 24). This allows the ACS726 current sensor IC to be used in high-side current sense applications without the use of high-side differential amplifiers or other costly isolation techniques. The ACS726 is provided in a small, low-profile surface mount QSOP24 package (suffix LF). The leadframe is plated with 100% matte tin, which is compatible with standard lead (Pb) free printed circuit board assembly processes. Internally, the device is Pb-free, except for flip-chip high-temperature Pb-based solder balls, currently exempt from RoHS. The device, excluding the BAE, is fully calibrated prior to shipment from the factory. Selection Guide Operating Optimized Range for Linear Range for Sensitivity, Ambient Tempera- 2 Part Number Sensed Current, I Sensed Current, I Sens (Typ) Packing P P ture Range 1 (A) (A) (mV/A) T , (C) A 3 ACS726LLFTR-20B-T 20 20 100 Tape and reel, 2500 40 to 150 3 pieces per 13-in. reel ACS726LLFTR-40B-T 40 40 50 1 Measured differently when V = 3.3 V and using a 2000 mV dynamic range. CC 2 Contact Allegro for additional packing options. 3 Variant not intended for automotive applications. Allegro MicroSystems, LLC 2 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000 www.allegromicro.com