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Contents

README

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ACS709LLFTR-20BB-T

Allegro MicroSystems, LLC · Current Sensors · QSOP-24

ACS709LLFTR-20BB-T from Allegro MicroSystems, LLC, in a QSOP-24. Pinout and pin descriptions extracted from the manufacturer datasheet (extract_pins, cross-checked by a second model); symbol, footprint, and 3D from KiCad-official CAD.

Pinout

Pin Name Type Function
1 IP+ passive Sensed current copper conduction path terminal, fused internally and looped to the IP- pins; supports unidirectional or bidirectional current flow (pins 1 through 6).
2 IP+ passive Sensed current copper conduction path terminal, fused internally and looped to the IP- pins; supports unidirectional or bidirectional current flow (pins 1 through 6).
3 IP+ passive Sensed current copper conduction path terminal, fused internally and looped to the IP- pins; supports unidirectional or bidirectional current flow (pins 1 through 6).
4 IP+ passive Sensed current copper conduction path terminal, fused internally and looped to the IP- pins; supports unidirectional or bidirectional current flow (pins 1 through 6).
5 IP+ passive Sensed current copper conduction path terminal, fused internally and looped to the IP- pins; supports unidirectional or bidirectional current flow (pins 1 through 6).
6 IP+ passive Sensed current copper conduction path terminal, fused internally and looped to the IP- pins; supports unidirectional or bidirectional current flow (pins 1 through 6).
7 IP- passive Sensed current copper conduction path terminal, fused internally and looped to the IP+ pins; supports unidirectional or bidirectional current flow (pins 7 through 12).
8 IP- passive Sensed current copper conduction path terminal, fused internally and looped to the IP+ pins; supports unidirectional or bidirectional current flow (pins 7 through 12).
9 IP- passive Sensed current copper conduction path terminal, fused internally and looped to the IP+ pins; supports unidirectional or bidirectional current flow (pins 7 through 12).
10 IP- passive Sensed current copper conduction path terminal, fused internally and looped to the IP+ pins; supports unidirectional or bidirectional current flow (pins 7 through 12).
11 IP- passive Sensed current copper conduction path terminal, fused internally and looped to the IP+ pins; supports unidirectional or bidirectional current flow (pins 7 through 12).
12 IP- passive Sensed current copper conduction path terminal, fused internally and looped to the IP+ pins; supports unidirectional or bidirectional current flow (pins 7 through 12).
13 NC unconnected No connection.
14 NC unconnected No connection.
15 GND power_in Device ground connection.
16 VZCR output Voltage reference output giving the zero current (0 A) reference, equal to 0.5 × VCC and scaling with VCC; can source 3 mA minimum and sink 50 µA minimum.
17 FILTER passive Terminal for an external capacitor to GND that sets the device bandwidth; absolute maximum voltage is 8 V.
18 VIOUT output Analog output voltage proportional to the current flowing between the IP+ and IP- pins; load must be at least 10 kΩ and no more than 10 nF to GND.
19 FAULT output Active-low open-drain overcurrent fault output that goes low when the current between IP+ and IP- exceeds the fault threshold; VFAULT is 0.4 V maximum at 1 mA sink.
20 VCC power_in Supply voltage pin, operating range 3 to 5.5 V (absolute maximum 8 V).
21 VOC input Overcurrent input whose analog voltage sets the overcurrent fault threshold, valid from 0.25×VCC to 0.4×VCC (absolute maximum 8 V).
22 FAULT_EN input Enables overcurrent faulting when high and resets FAULT when low; VIH is 0.8×VCC minimum and VIL is 0.1×VCC maximum.
23 NC unconnected No connection.
24 NC unconnected No connection.

Key specifications

Parameter Value
Manufacturer Allegro MicroSystems, LLC
Package QSOP-24
Category Sensors
Pins 24

Electrical characteristics

Limits as printed in the datasheet (page.json metadata.characteristics carries them as data).

Parameter Symbol Min Typ Max Unit Conditions Page
Supply Voltage VCC 3 5.5 V 4
Nominal Supply Voltage VCCN 5 V 4
Supply Current ICC 11 14.5 mA VIOUT open, FAULT pin high 4
Output Capacitance Load CLOAD 10 nF VIOUT pin to GND 4
Output Resistive Load RLOAD 10 kΩ VIOUT pin to GND 4
Full Range Linearity ELIN -0.75 0.25 0.75 % IP = ±IP0A 4
Symmetry ESYM 99.1 100 100.9 % IP = ±IP0A 4
Setting Voltage for Overcurrent Switch Point VOC 0.25 0.4 xVCC 4
Overcurrent FAULT Pin Output Voltage VFAULT 0.4 V 1 mA sink current at FAULT pin 4
FAULT_EN Input Low Voltage Threshold VIL 0.1 xVCC 4
FAULT_EN Input High Voltage Threshold VIH 0.8 xVCC 4
Overcurrent Input Pin Resistance ROC 2 MΩ TA = 25°C, VOC pin to GND 5
Voltage Reference Output Load Current (source) IZCR 3 mA Source current 5
Voltage Reference Output Load Current (sink) IZCR 50 µA Sink current 5
Voltage Reference Output VZCR 0.5 xVCC TA = 25 °C 5
Voltage Reference Output Drift ΔVZCR 10 mV 5
Optimized Accuracy Range IP(OA) -20 20 A 6
Linear Sensing Range IP(LIN) -37.5 37.5 A 6
Sensitivity Sens 54.5 58 mV/A IP = 12.5 A, TA = 25°C to 150°C 6
Sensitivity Sens 54.5 58.5 mV/A IP = 12.5 A, TA =, 40°C to 25°C 6
Sensitivity Sens 56 mV/A IP = 12.5 A, TA = 25°C 6
Electrical Offset Voltage VOE -25 25 mV IP = 0 A, TA = 25°C to 150°C 6
Electrical Offset Voltage VOE -40 40 mV IP = 0 A, TA =, 40°C to 25°C 6
Electrical Offset Voltage VOE 5 mV IP = 0 A, TA = 25°C (±5) 6
Total Output Error ETOT 2 % Tested at IP =12.5 A, IP applied for 5 ms, TA = 25°C to 150°C (±2) 6
Total Output Error ETOT 3 % Tested at IP =12.5 A, IP applied for 5 ms, TA =, 40°C to 25°C (±3) 6
Noise VNOISE(rms) 1.5 mV TA = 25°C, Sens = 56 mV/A, Cf = 0, CLOAD = 4.7 nF, RLOAD open 6
Magnetic Coupling to Hall Element MCHALL 9.5 G/A Current flowing from IP+ to IP- pins 4
Internal Filter Resistance RF(INT) 1.7 kΩ 4
Primary Conductor Resistance RPRIMARY 1.1 mΩ TA = 25°C 4
Bidirectional Quiescent Output VOUT(QBI) 0.5 xVCC IP = 0 A, TA = 25°C 4
VIOUT Signal Rise Time tr 3 μs TA = 25°C, no capacitor on FILTER pin, 100 pF from VIOUT to GND 4
VIOUT Signal Response Time tRESPONSE 4 μs TA = 25°C, no capacitor on FILTER pin, 100 pF from VIOUT to GND 4
Large Signal Bandwidth f3dB 120 kHz -3 dB, TA = 25°C, no capacitor on FILTER pin 4
Overcurrent Fault Switch Point Error EOC 5 % Switch point in VOC safe operating area; assumes INCOMP = 0 A (±5) 4
Overcurrent Fault Response Time tOC 1.9 μs VOC = 0.25 × VCC, without external COC capacitor 5
Supply Voltage VCC 8 V 2
Analog Output Pin Voltage VIOUT 32 V 2
DC Reverse Voltage VRdcx -0.5 V Supply, Filter, Analog Output, Overcurrent Input, Overcurrent Fault, Fault Enable, Voltage Reference Output pins 2
Output Current Source IIOUT(Source) 3 mA 2
Output Current Sink IIOUT(Sink) 1 mA 2
Operating Ambient Temperature TA -40 150 °C Range L 2
Junction Temperature TJ(max) 165 °C 2
Storage Temperature Tstg -65 170 °C 2
Steady State Package Thermal Resistance RθJA 21 °C/W Tested with 30 A DC current, ACS709 demo board in 1 cu. ft. of still air 8

Materials and finish

As the datasheet states them (page.json metadata.appearance; the 3D model's colours follow it).

Part Material Colour / plating Datasheet says Page
contacts tin [1] -S denotes the lead-free construction with tin-silver-based solder bumps. [2] -T denotes Pb-contained construction with Pb-based solder bumps. Operating performance of -T and -S devices are identi 2

CAD (KiCad official)

  • Symbol: ACS709LLFTR-20BB-T
  • Footprint: Package_SO:QSOP-24_3.9x8.7mm_P0.635mm
  • 3D model: QSOP-24 (KiCad packages3D, STEP)
  • 3D model files: acs709llftr-20bb-t-etched.step / acs709llftr-20bb-t-etched.glb carry the MPN laser-etched on the die in a toggleable Adom.LaserEtch group (Fusion-ready); acs709llftr-20bb-t.step / acs709llftr-20bb-t.glb are the bare package body.

Provenance

Data extracted from the manufacturer datasheet, not a distributor listing:

  • Datasheet: Allegro MicroSystems, LLC datasheet (20 pp, sha256 01ee6a3818374c8e, retrieved 2026-10-23, tier: lcsc)
  • Extractor: parts-factory 2.0.0 / extract_pins 0.3, primary claude-sonnet-5-5 (text), consensus claude-sonnet-5-5 (agreed), guards: pin_guards 0.1: passed. Pins are checked against the footprint pad set and their cited datasheet pages before publish.
  • CAD: KiCad official libraries (CC-BY-SA 4.0).

Datasheet PDF