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acs709 description the allegro ? acs709 current sensor ic provides economical and precise means for current sensing applications in industrial, automotive, commercial, and communications systems. the device is offered in a small footprint surface mount package that allows easy implementation in customer applications. the acs709 consists of a precision linear hall sensor integrated circuit with a copper conduction path located near the surface of the silicon die. applied current flows through the copper conduction path, and the analog output voltage from the hall sensor ic linearly tracks the magnetic field generated by the applied current. the accuracy of the acs709 is maximized with this patented packaging configuration because the hall element is situated in extremely close proximity to the current to be measured. high level immunity to current conductor dv/dt and stray electric fields, offered by allegro proprietary integrated shield technology, provides low output ripple and low offset drift in high-side applications. the voltage on the overcurrent input (voc pin) allows customers to define an overcurrent fault threshold for the device. when the current flowing through the copper conduction path (between the ip+ and ipC pins) exceeds this threshold, acs709a-ds, rev. 4 features and benefits ? industry-leading noise performance with 120 khz bandwidth through proprietary amplifier and filter design techniques ? integrated shield greatly reduces capacitive coupling from current conductor to die due to high dv/dt, and prevents offset drift in high-side applications ? small footprint surface-mount qsop24 package ? high isolation voltage, suitable for line-powered applications ? 1.1 m primary conductor resistance for low power loss ? user-settable overcurrent fault level ? overcurrent fault signal typically responds to an overcurrent condition in < 2 s ? filter pin capacitor sets analog signal bandwidth ? 2% typical output error ? 3 to 5.5 v, single supply operation ? factory trimmed sensitivity, quiescent output voltage, and associated temperature coefficients ? chopper stabilization results in extremely stable quiescent output voltage ? ratiometric output from supply voltage high-bandwidth, fast fault response current sensor ic in thermally enhanced package continued on the next page typical application r h , r l sets resistor divider reference for v oc c f noise and bandwidth limiting filter capacitor c oc fault delay setting capacitor, 22 nf maximum a use of capacitor required b use of resistor optional package: 24 pin qsop (suffix lf) approximate scale 1 2 3 4 5 6 7 8 9 10 11 12 ip+ ip+ ip+ ip+ ip+ ip+ ip? ip? ip? ip? ip? ip? 22 21 20 19 18 17 16 15 nc nc fault_en voc vcc fault viout filter vzcr gnd nc nc acs709 0.1 f c oc c f 330 k? 1 nf v iout fault_en v cc r h r l i p b a 24 23 14 13
2 isolation characteristics characteristic symbol notes rating unit dielectric strength test voltage* v iso agency type-tested for 60 seconds per ul standard 1577 2100 vac working voltage for basic isolation v wfsi for basic (single) isolation per ul standard 1577; for higher continuous voltage ratings, please contact allegro 277 vac * allegro does not conduct 60-second testing. it is done only during the ul certification process. selection guide part number i p(lin) (a) sens (typ) (mv/a) t a (c) packing* acs709llftr-35bb-t 75 28 (v cc = 5 v) C40 to 150 t ape and reel, 2500 pieces per reel acs709llftr-20bb-t 37.5 56 (v cc = 5 v) acs709llftr-10bb-t 24 85 (v cc = 5 v) acs709llftr-6bb-t 15 90 (v cc = 3.3 v) *contact allegro for packing options. the open drain overcurrent fault pin will transition to a logic low state. factory programming of the linear hall sensor ic inside of the acs709 results in exceptional accuracy in both analog and digital output signals. the internal resistance of the copper path used for current sensing is typically 1.1 m?, for low power loss. also, the current conduction path is electrical ly isolated from the low voltage device inputs and outputs. this allows the acs709 family of sensor ics to be used in applications requiring electrical isolation, without the use of opto-isolators or other costly isolation techniques. applications include: ? motor control and protection ? load management and overcurrent detection ? power conversion and battery monitoring / ups systems description (continued) absolute maximum ratings characteristic symbol notes rating units supply voltage v cc 8 v filter pin v filter 8 v analog output pin v iout 32 v overcurrent input pin v oc 8 v overcurrent f a u l t pin v f a u l t 8 v fault enable (fault_en) pin v faulten 8 v voltage reference output pin v zcr 8 v dc reverse voltage: supply voltage, filter, analog output, overcurrent input, overcurrent fault, fault enable, and voltage reference output pins v rdcx C0.5 v output current source i iout(source) 3 ma output current sink i iout(sink) 1 ma operating ambient temperature t a range l C40 to 150 c junction temperature t j (max) 165 c storage temperature t stg C65 to 170 c high-bandwidth, fast fault response current sensor ic in thermally enhanced package acs709 allegro microsystems, llc 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com
3 ip? vzcr filter gnd viout drain ip+ fault signal recovery v out(q) trim sensitivity trim r q clk d voc vcc por fault reset 3 ma 2v ref por hall bias control logic fault_en + ? + ? fault comparator hall amplifier r f(int) 1 2 3 4 5 6 7 8 9 10 11 12 24 23 22 21 20 19 18 17 16 15 14 13 ip+ ip+ ip+ ip+ ip+ ip+ ip? ip? ip? ip? ip? ip? nc nc fault_en voc vcc fault viout filter vzcr gnd nc nc terminal list table number name description 1 through 6 ip+ sensed current copper conduction path pins. terminals for current being sensed; fused internally, loop to ipC pins; unidirectional or bidirectional current flow. 7 through 12 ipC sensed current copper conduction path pins. terminals for current being sensed; fused internally, loop to ip+ pins; unidirectional or bidirectional current flow. 13, 14, 23, 24 nc no connection 15 gnd device ground connection. 16 vzcr voltage reference output pin. zero current (0 a) reference; output voltage on this pin scales with v cc . 17 filter filter pin. terminal for an external capacitor connected from this pin to gnd to set the device bandwidth. 18 viout analog output pin. output voltage on this pin is proportional to current flowing through the loop between the ip+ pins and ipC pins. 19 f a u l t overcurrent fault pin. when current flowing between ip+ pins and ipC pins exceeds the overcurrent fault threshold, this pin transitions to a logic low state. 20 vcc supply voltage. 21 voc overcurrent input pin. analog input voltage on this pin sets the overcurrent fault threshold. 22 fault_en enables overcurrent faulting when high. resets f a u l t when low . functional block diagram pinout diagram high-bandwidth, fast fault response current sensor ic in thermally enhanced package acs709 allegro microsystems, llc 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com
4 common operating characteristics: valid at t a = C40c to 150c, v cc = 5 v (3.3 v for -6bb version), unless otherwise specified characteristic symbol t est conditions min. typ. max. units electrical characteristics supply voltage 1 v cc 3 C 5.5 v nominal supply voltage v ccn C 5 C v supply current i cc viout open, fault pin high, v cc = 5 v (all versions but -6bb) C 11 14.5 ma viout open, fault pin high, v cc = 3.3 v (-6bb version) C 9 11 ma output capacitance load c load viout pin to gnd C C 10 nf output resistive load r load viout pin to gnd 10 C C k magnetic coupling from device conductor to hall element mc hall current flowing from ip+ to ipC pins C 9.5 C g/a internal filter resistance 2 r f(int) C 1.7 C k? primary conductor resistance r primary t a = 25c C 1.1 C m analog output signal characteristics full range linearity 3 e lin i p = i p0a C0.75 0.25 0.75 % symmetry 4 e sym i p = i p0a 99.1 100 100.9 % bidirectional quiescent output v out(qbi) i p = 0 a, t a = 25c C v cc 0.5 C v timing performance characteristics viout signal rise time t r t a = 25c, swing i p from 0 a to i p0a , no capacitor on filter pin, 100 pf from viout to gnd C 3 C s viout signal propagation time t prop t a = 25c, no capacitor on filter pin, 100 pf from viout to gnd C 1 C s viout signal response time t response t a = 25c, swing i p from 0 a to i p0a , no capacitor on filter pin, 100 pf from viout to gnd C 4 C s viout large signal bandwidth 5 f 3db C3 db, t a = 25c, no capacitor on filter pin, 100 pf from viout to gnd C 120 C khz power-on time t po output reaches 90% of steady-state level, no capacitor on filter pin, t a = 25c C 35 C s overcurrent characteristics setting voltage for overcurrent switchpoint 6 v oc v cc 0.25 C v cc 0.4 v signal noise at overcurrent comparator input i ncomp C 1 C a overcurrent fault switchpoint error 7,8 e oc switchpoint in v oc safe operating area; assumes i ncomp = 0 a C 5 C % overcurrent f a u l t pin output v oltage v f a u l t 1 ma sink current at f a u l t pin C C 0.4 v fault enable (f ault_en pin) input low voltage threshold v il C C 0.1 v cc v fault enable (fault_en pin) input high voltage threshold v ih 0.8 v cc C C v fault enable (fault_en pin) input resistance r fei C 1 C m? continued on the next page high-bandwidth, fast fault response current sensor ic in thermally enhanced package acs709 allegro microsystems, llc 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com
5 overcurrent characteristics (continued) fault enable (fault_en pin) delay 9 t fed set fault_en to low, v oc = 0.25 v cc , c oc = 0 f; then run a dc i p exceeding the corresponding overcurrent threshold; then reset fault_en from low to high and measure the delay from the rising edge of fault_en to the falling edge of f a u l t C 15 C s overcurrent fault response time t oc fault_en set to high for a minimum of 20 s before the overcurrent event; switchpoint set at v oc = 0.25 v cc ; delay from i p exceeding overcurrent fault threshold to v f a u l t < 0.4 v, without external c oc capacitor C 1.9 C s overcurrent fault reset delay t ocr time from v faulten < v il to v fault > 0.8 v cc , r pu = 330 k C 500 C ns overcurrent fault reset hold time t och time from v faulten pin < v il to reset of fault latch; see functional block diagram C 250 C ns overcurrent input pin resistance r oc t a = 25c, voc pin to gnd 2 C C m voltage reference characteristics voltage reference output v zcr t a = 25 c C 0.5 v cc C v voltage reference output load current i zcr source current 3 C C ma sink current 50 C C a voltage reference output drift ?v zcr C 10 C mv 1 devices are trimmed for maximum accuracy at v cc = 5 v. the ratiometry feature of the device allows operation over the full v cc range; however, accuracy may be slightly degraded for v cc values other than 5 v. contact the allegro factory for applications that require maximum accuracy for v cc = 3.3 v. 2 r f(int) forms an rc circuit via the filter pin. 3 this parameter can drift by as much as 0.25% over the lifetime of this product. 4 this parameter can drift by as much as 0.3% over the lifetime of this product. 5 calculated using the formula f 3db = 0.35 / t r . 6 see page 8 on how to set overcurrent fault switchpoint. 7 switchpoint can be lower at the expense of switchpoint accuracy. 8 this error specification does not include the effect of noise. see the i ncomp specification in order to factor in the additional influence of noise on the fault switchpoint. 9 fault enable delay is designed to avoid false tripping of an overcurrent (oc) fault at power-up. a 15 s (typical) delay will always be needed, every time f ault_en is raised from low to high, before the device is ready for responding to any overcurrent event. common operating characteristics (continued): valid at t a = C40c to 150c, v cc = 5 v (3.3 v for -6bb version), unless otherwise specified characteristic symbol t est conditions min. typ. max. units high-bandwidth, fast fault response current sensor ic in thermally enhanced package acs709 allegro microsystems, llc 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com
6 x6bb performance characteristics , t a range l, valid at t a = C?40c to 150c, v cc = 3.3 v, unless otherwise specified characteristic symbol test conditions min. typ. max. units optimized accuracy range i p(oa) C6.5 C 6.5 a linear sensing range i p(lin) C15 C 15 a performance characteristics at v cc = 3.3 v noise 1 v noise(rms) t a = 25c, sens = 90 mv/a, c f = 0, c load = 4.7 nf, r load open C 2.5 C mv sensitivity 2,3 sens i p = 6.5 a, t a = 25c C 90 C mv/a i p = 6.5 a, t a = 25c to 150c 85 C 95 mv/a i p = 6.5 a, t a = C?40c to 25c 83 C 97 mv/a electrical offset voltage 2 v oe i p = 0 a, t a = 25c C 5 C mv i p = 0 a, t a = 25c to 150c C30 C 30 mv i p = 0 a, t a = C?40c to 25c C45 C 45 mv total output error 2,4 e tot tested at i p = 6.5 a?, i p applied for 5 ms, t a = 25c to 150c C 2 C % tested at i p = 6.5 a?, i p applied for 5 ms, t a = C?40c to 25c C 4 C % 1 v pk-pk noise (6 sigma noise) is equal to 6 v noise(rms) . lower noise levels than this can be achieved by using c f for applications requiring narrower bandwidth. see characteristic performance page for graphs of noise versus c f and bandwidth versus c f . 2 see characteristic performance data graphs for parameter distribution over ambient temperature range. 3 this parameter can drift by as much as 1.75% over lifetime of the product. 4 this parameter can drift by as much as 2.5% over lifetime of the product. x10bb performance characteristics , t a range l, valid at t a = C?40c to 150c, v cc = 5 v, unless otherwise specified characteristic symbol test conditions min. typ. max. units optimized accuracy range i p(oa) C10 C 10 a linear sensing range i p(lin) C24 C 24 a performance characteristics at v cc = 5 v noise 1 v noise(rms) t a = 25c, sens = 85 mv/a, c f = 0, c load = 4.7 nf, r load open C 2.3 C mv sensitivity 2,3 sens i p = 10 a, t a = 25c C 85 C mv/a i p = 10 a, t a = 25c to 150c 82 85 88 mv/a i p = 10 a, t a = C?40c to 25c 80 85 90 mv/a electrical offset voltage 2 v oe i p = 0 a, t a = 25c C 5 C mv i p = 0 a, t a = 25c to 150c C30 C 30 mv i p = 0 a, t a = C?40c to 25c C45 C 45 mv total output error 2,4 e tot tested at i p =10 a?, i p applied for 5 ms, t a = 25c to 150c C 2 C % tested at i p =10 a?, i p applied for 5 ms, t a = C?40c to 25c C 4 C % 1 v pk-pk noise (6 sigma noise) is equal to 6 v noise(rms) . lower noise levels than this can be achieved by using c f for applications requiring narrower bandwidth. see characteristic performance page for graphs of noise versus c f and bandwidth versus c f . 2 see characteristic performance data graphs for parameter distribution over ambient temperature range. 3 this parameter can drift by as much as 1.75% over lifetime of the product. 4 this parameter can drift by as much as 2.5% over lifetime of the product. high-bandwidth, fast fault response current sensor ic in thermally enhanced package acs709 allegro microsystems, llc 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com
7 x35bb performance characteristics , t a range l, valid at t a = C?40c to 150c, v cc = 5 v, unless otherwise specified characteristic symbol test conditions min. typ. max. units optimized accuracy range i p(oa) C37.5 C 37.5 a linear sensing range i p(lin) C75 C 75 a performance characteristics at v cc = 5 v noise 1 v noise(rms) t a = 25c, sens = 28 mv/a, c f = 0, c load = 4.7 nf, r load open C 1 C mv sensitivity 2,3 sens i p = 25 a, t a = 25c C 28 C mv/a i p = 25 a, t a = 25c to 150c 27 C 29.5 mv/a i p = 25 a, t a = C?40c to 25c 27 C 29.5 mv/a electrical offset voltage 2 v oe i p = 0 a, t a = 25c C 5 C mv i p = 0 a, t a = 25c to 150c C25 C 25 mv i p = 0 a, t a = C?40c to 25c C40 C 40 mv total output error 2,4 e tot tested at i p = 25 a?, i p applied for 5 ms, t a = 25c to 150c C 3 C % tested at i p = 25 a?, i p applied for 5 ms, t a = C?40c to 25c C 3 C % 1 v pk-pk noise (6 sigma noise) is equal to 6 v noise(rms) . lower noise levels than this can be achieved by using c f for applications requiring narrower bandwidth. see characteristic performance page for graphs of noise versus c f and bandwidth versus c f . 2 see characteristic performance data graphs for parameter distribution over ambient temperature range. 3 this parameter can drift by as much as 1.75% over lifetime of the product. 4 this parameter can drift by as much as 2.5% over lifetime of the product. x20bb performance characteristics , t a range l, valid at t a = C?40c to 150c, v cc = 5 v, unless otherwise specified characteristic symbol test conditions min. typ. max. units optimized accuracy range i p(oa) C20 C 20 a linear sensing range i p(lin) C37.5 C 37.5 a performance characteristics at v cc = 5 v noise 1 v noise(rms) t a = 25c, sens = 56 mv/a, c f = 0, c load = 4.7 nf, r load open C 1.50 C mv sensitivity 2,3 sens i p = 12.5 a, t a = 25c C 56 C mv/a i p = 12.5 a, t a = 25c to 150c 54.5 C 58 mv/a i p = 12.5 a, t a = C?40c to 25c 54.5 C 58.5 mv/a electrical offset voltage 2 v oe i p = 0 a, t a = 25c C 5 C mv i p = 0 a, t a = 25c to 150c C25 C 25 mv i p = 0 a, t a = C?40c to 25c C40 C 40 mv total output error 2,4 e tot tested at i p =12.5 a?, i p applied for 5 ms, t a = 25c to 150c C 2 C % tested at i p =12.5 a?, i p applied for 5 ms, t a = C?40c to 25c C 3 C % 1 v pk-pk noise (6 sigma noise) is equal to 6 v noise(rms) . lower noise levels than this can be achieved by using c f for applications requiring narrower bandwidth. see characteristic performance page for graphs of noise versus c f and bandwidth versus c f . 2 see characteristic performance data graphs for parameter distribution over ambient temperature range. 3 this parameter can drift by as much as 1.75% over lifetime of the product. 4 this parameter can drift by as much as 2.5% over lifetime of the product. high-bandwidth, fast fault response current sensor ic in thermally enhanced package acs709 allegro microsystems, llc 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com
8 thermal characteristics characteristic symbol test conditions value units steady state package thermal resistance r ja tested with 30 a dc current and based on acs709 demo board in 1 cu. ft. of still air. please refer to product faqs page on allegro web site for detailed information on acs709 demo board. 21 oc/w transient package thermal resistance r tja tested with 30 a dc current and based on acs709 demo board in 1 cu. ft. of still air. please refer to product faqs page on allegro web site for detailed information on acs709 demo board. see graph oc/w 0 2 4 6 8 10 12 14 16 18 20 22 0.01 0.1 1 10 100 1000 thermal resistance (c/w) time (sec) acs709 transient package thermal resistance on 85--0444 demo board (no al plate) high-bandwidth, fast fault response current sensor ic in thermally enhanced package acs709 allegro microsystems, llc 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com
9 acs709 bandwidth versus external capacitor value, c f capacitor connected between filter pin and gnd 1000 100 10 1 0.1 0.01 0.1 1 10 100 1000 bandwidth (khz) capacitance (nf) characteristic performance acs709x-35b v cc = 5 v acs709x-35b v cc = 3.3 v acs709x-20b v cc = 5 v acs709x-20b v cc = 3.3 v capacitance (nf) capacitance (nf) capacitance (nf) capacitance (nf) rms noise (v) rms noise (v) rms noise (v) rms noise (v) 400 500 600 700 800 900 1000 0 10 20 30 40 50 300 400 500 600 700 800 900 0 10 20 30 40 50 0 200 400 600 800 1000 1200 1400 1600 0 10 20 30 40 50 0 200 400 600 800 1000 1200 1400 1600 0 10 20 30 40 50 acs709 noise versus external capacitor value, c f capacitor connected between filter pin and gnd high-bandwidth, fast fault response current sensor ic in thermally enhanced package acs709 allegro microsystems, llc 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com
10 characteristic performance data data taken using the acs709-6bb, v cc = 3.3 v accuracy data mean typical maximum limit typical minimum limit 30 20 10 0 -10 -20 -30 -40 0.50 0.40 0.30 0.20 0.10 0 -0.10 -0.20 -0.30 -0.40 93.0 92.0 91.0 90.0 89.0 88.0 87.0 86.0 85.0 100.4 100.3 100.2 100.1 100.0 99.9 99.8 99.7 99.6 99.5 4 2 0 -2 -4 -6 -8 v oe (mv) e lin (%) sens (mv/a) e sym (%) e tot (%) t a (c) t a (c) t a (c) t a (c) t a (c) ?50 100 125 150 50 0 -25 25 75 ?50 100 125 150 50 0 -25 25 75 ?50 100 125 150 50 0 -25 25 75 ?50 100 125 150 50 0 -25 25 75 ?50 100 125 150 50 0 -25 25 75 electrical offset voltage versus ambient temperature nonlinearity versus ambient temperature sensitivity versus ambient temperature total output error versus ambient temperature symmetry versus ambient temperature high-bandwidth, fast fault response current sensor ic in thermally enhanced package acs709 allegro microsystems, llc 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com
11 characteristic performance data data taken using the acs709-10bb, v cc = 5 v accuracy data mean typical maximum limit typical minimum limit 30 20 10 0 -10 -20 -30 -40 0.30 0.20 0.10 0 -0.10 -0.20 -0.30 -0.40 -0.50 86.5 86.0 85.5 85.0 84.5 84.0 83.5 83.0 82.5 82.0 100.5 100.4 100.3 100.2 100.1 100.0 99.9 99.8 99.7 99.6 99.5 3.00 2.00 1.00 0 -1.00 -2.00 -3.00 -4.00 -5.00 -6.00 v oe (mv) e lin (%) sens (mv/a) e sym (%) e tot (%) t a (c) t a (c) t a (c) t a (c) t a (c) ?50 100 125 150 50 0 -25 25 75 ?50 100 125 150 50 0 -25 25 75 ?50 100 125 150 50 0 -25 25 75 ?50 100 125 150 50 0 -25 25 75 ?50 100 125 150 50 0 -25 25 75 electrical offset voltage versus ambient temperature nonlinearity versus ambient temperature sensitivity versus ambient temperature total output error versus ambient temperature symmetry versus ambient temperature high-bandwidth, fast fault response current sensor ic in thermally enhanced package acs709 allegro microsystems, llc 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com
12 characteristic performance data data taken using the acs709-20bb, v cc = 5 v accuracy data mean typical maximum limit typical minimum limit 20 15 10 5 0 -5 -10 -15 -20 -25 -30 -35 0.20 0.15 0.10 0.05 0 -0.05 -0.10 -0.15 -0.20 -0.25 -0.30 58.0 57.5 57.0 56.5 56.0 55.5 55.0 100.8 100.6 100.4 100.2 100.0 99.8 99.6 99.4 4 3 2 1 0 -1 -2 -3 -4 v oe (mv) e lin (%) sens (mv/a) e sym (%) e tot (%) t a (c) t a (c) t a (c) t a (c) t a (c) ?50 100 125 150 50 0 -25 25 75 ?50 100 125 150 50 0 -25 25 75 ?50 100 125 150 50 0 -25 25 75 ?50 100 125 150 50 0 -25 25 75 ?50 100 125 150 50 0 -25 25 75 electrical offset voltage versus ambient temperature nonlinearity versus ambient temperature sensitivity versus ambient temperature total output error versus ambient temperature symmetry versus ambient temperature high-bandwidth, fast fault response current sensor ic in thermally enhanced package acs709 allegro microsystems, llc 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com
13 characteristic performance data data taken using the acs709-35bb, v cc = 5 v accuracy data mean typical maximum limit typical minimum limit 20 15 10 5 0 -5 -10 -15 -20 -25 0.30 0.20 0.10 0 -0.10 -0.20 -0.30 29.0 28.8 28.6 28.4 28.2 28.0 27.8 27.6 27.4 101.0 100.8 100.6 100.4 100.2 100.0 99.8 99.6 99.4 99.2 99.0 4 3 2 1 0 -1 -2 -3 -4 v oe (mv) e lin (%) sens (mv/a) e sym (%) e tot (%) t a (c) t a (c) t a (c) t a (c) t a (c) ?50 100 125 150 50 0 -25 25 75 ?50 100 125 150 50 0 -25 25 75 ?50 100 125 150 50 0 -25 25 75 ?50 100 125 150 50 0 -25 25 75 ?50 100 125 150 50 0 -25 25 75 electrical offset voltage versus ambient temperature nonlinearity versus ambient temperature sensitivity versus ambient temperature total output error versus ambient temperature symmetry versus ambient temperature high-bandwidth, fast fault response current sensor ic in thermally enhanced package acs709 allegro microsystems, llc 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com
14 setting 20bb and 35bb versions the v oc needed for setting the overcurrent fault switchpoint can be calculated as follows: v oc = sens | i oc | , where v oc is in mv, sens in mv/a, and i oc (overcur- rent fault switchpoint) in a. | ioc | is the overcurrent fault switchpoint for a bi- directional (ac) current, which means a bi-directional device will have two symmetrical overcurrent fault switchpoints, +i oc and Ci oc . see the following graph for i oc and v oc ranges. setting overcurrent fault switchpoint i oc v oc 0. 4 v cc ? 0.25 v cc / sens ? 0. 4 v cc / sens 0 0.25 v cc / sens 0. 4 v cc / sens not in valid range in valid range 0. 25 v cc example: for acs709llftr-35bb-t, if required overcurrent fault switchpoint is 50 a, and v cc = 5 v, then the required v oc can be calculated as follows: v oc = sens i oc = 28 50 = 1400 (mv) i oc versus v oc (20bb and 35bb versions) high-bandwidth, fast fault response current sensor ic in thermally enhanced package acs709 allegro microsystems, llc 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com
15 setting 10bb and 6bb versions the v oc needed for setting the overcurrent fault switchpoint can be calculated as follows: v oc = 1.17 sens | i oc | , where v oc is in mv, sens in mv/a, and i oc (overcur- rent fault switchpoint) in a. | ioc | is the overcurrent fault switchpoint for a bi- directional (ac) current, which means a bi-directional sensor will have two symmetrical overcurrent fault switchpoints, +i oc and Ci oc . see the following graph for i oc and v oc ranges. i oc v oc 0.4 v cc ? 0.2 5 v cc / (1.17 sens) ? 0. 4 v cc / (1.17 sens) 0 0.25 v cc / (1.17 sens) 0. 4 v cc / (1.17 sens) not valid range valid range 0.25 v cc i oc versus v oc (10bb and 6bb versions) example: for acs709llftr-6bb-t, if required overcurrent fault switchpoint is 10 a, and v cc = 3.3 v, then the required v oc can be calculated as follows: v oc = 1.17 sens i oc = 1.17 90 10 = 1053 (mv) high-bandwidth, fast fault response current sensor ic in thermally enhanced package acs709 allegro microsystems, llc 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com
16 overcurrent fault operation the primary concern with high-speed fault detection is that noise may cause false tripping. various applications have or need to be able to ignore certain faults that are due to switching noise or other parasitic phenomena, which are application dependant. the problem with simply trying to filter out this noise up front is that in high-speed applications, with asymmetric noise, the act of filtering introduces an error into the measurement. to get around this issue, and allow the user to prevent the fault signal from being latched by noise, a circuit was designed to slew the f a u l t pin voltage based on the value of the capacitor from that pin to ground. once the voltage on the pin falls below 2 v, as estab- lished by an internal reference, the fault output is latched and pulled to ground quickly with an internal n-channel mosfet. fault walk-through the following walk-through references various sections and attributes in the figure below. this figure shows different fault set/reset scenarios and how they relate to the voltages on the f a u l t pin, fault_en pin, and the internal overcurrent (oc) fault node, which is invisible to the customer. 1. because the device is enabled (f ault_en is high for a mini- mum period of time, the fault enable delay, t fed , 15 s typical) and there is an oc fault condition, the device f a u l t pin starts dischar ging. 2. when the f a u l t pin voltage reaches approximately 2 v , the fault is latched, and an internal nmos device pulls the f a u l t pin voltage to approximately 0 v . the rate at which the f a u l t pin slews downward (see [4] in the figure) is dependent on the external capacitor, c oc , on the f a u l t pin. 3. when the f ault_en pin is brought low, the f a u l t pin starts resetting if no oc fault condition exists. the internal nmos pull-down turns off and an internal pmos pull-up turns on (see [7] if the oc fault condition still exists). 4. the slope, and thus the delay , on the fault is controlled by the capacitor, c oc , placed on the f a u l t pin to ground. during this portion of the fault (when the f a u l t pin is between v cc and 2 v), there is a 3 ma constant current sink, which discharges c oc . the length of the fault delay, t, is equal to : c oc ( v cc ? 2 v ) 3 ma t = (1) where v cc is the device power supply voltage. 5. the f a u l t pin did not reach the 2 v latch point before the oc fault condition cleared. because of this, the fixed 3 ma current sink turns off, and the internal pmos pull-up turns on to recharge c oc through the f a u l t pin. functional description v cc 2 v 0 v time t fed fault (output) fault_en (input) oc fault condition (active high) 2 3 6 6 6 8 1 1 1 4 2 7 4 2 4 4 5 high-bandwidth, fast fault response current sensor ic in thermally enhanced package acs709 allegro microsystems, llc 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com
17 6. this curve shows v cc charging external capacitor c oc through the internal pmos pull-up. the slope is determined by c oc . 7. when the f ault_en pin is brought low, if the fault condi- tion still exists, the latched f a u l t pin will stay low until the fault condition is removed, then it will start resetting. 8. at this point there is a fault condition, and the part is enabled before the f a u l t pin can char ge to v cc . this shortens the user-set delay, so the fault is latched earlier. the new delay time can be calculated by equation 1, after substituting the voltage seen on the f a u l t pin for v cc . chopper stabilization technique chopper stabilization is an innovative circuit technique that is used to minimize the offset voltage of a hall element and an asso - ciated on-chip amplifier. allegro patented a chopper stabiliza- tion technique that nearly eliminates hall ic output drift induced by temperature or package stress effects. this offset reduction technique is based on a signal modulation-demodulation process. modulation is used to separate the undesired dc offset signal from the magnetically induced signal in the frequency domain. then, using a low-pass filter, the modulated dc offset is suppressed while the magnetically induced signal passes through the filter. as a result of this chopper stabilization approach, the output voltage from the hall ic is desensitized to the effects of tempera- ture and mechanical stress. this technique produces devices that have an extremely stable electrical offset voltage, are immune to thermal stress, and have precise recoverability after temperature cycling. this technique is made possible through the use of a bicmos process that allows the use of low-offset and low-noise amplifiers in combination with high-density logic integration and sample and hold circuits. am p r egu la to r clock/logic ha ll e lement sample an d hold low-p ass filte r concept of chopper stabilization technique high-bandwidth, fast fault response current sensor ic in thermally enhanced package acs709 allegro microsystems, llc 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com
18 sensitivity (sens). the change in device output in response to a 1 a change through the primary conductor. the sensitivity is the product of the magnetic circuit sensitivity (g / a) and the linear ic amplifier gain (mv/g). the linear ic amplifier gain is pro - grammed at the factory to optimize the sensitivity (mv/a) for the full-scale current of the device. noise (v noise ). the product of the linear ic amplifier gain (mv/g) and the noise floor for the allegro hall effect linear ic (1 g). the noise floor is derived from the thermal and shot noise observed in hall elements. dividing the noise (mv) by the sensitivity (mv/a) provides the smallest current that the device is able to resolve. linearity (e lin ). the degree to which the voltage output from the device varies in direct proportion to the primary current through its full-scale amplitude. nonlinearity in the output can be attributed to the saturation of the flux concentrator approaching the full-scale current. the following equation is used to derive the linearity: where v iout_full-scale amperes = the output voltage (v) when the sensed current approximates full-scale i p . symmetry (e sym ). the degree to which the absolute voltage output from the device varies in proportion to either a positive or negative full-scale primary current. the following formula is used to derive symmetry: quiescent output voltage (v iout(q) ). the output of the device when the primary current is zero. for a unipolar supply voltage, it nominally remains at 0.5v cc . for example, in the case of a bidirectional output device, v cc = 5 v translates into v iout(q) = 2.5 v. variation in v iout(q) can be attributed to the resolution of the allegro linear ic quiescent voltage trim and thermal drift. electrical offset voltage (v oe ). the deviation of the device out- put from its ideal quiescent voltage due to nonmagnetic causes. to convert this voltage to amperes, divide by the device sensitivity, sens. accuracy (e tot ). the accuracy represents the maximum devia- tion of the actual output from its ideal value. this is also known as the total ouput error. the accuracy is illustrated graphically in the output voltage versus current chart at right. note that error is directly measured during final test at allegro. accuracy is divided into four areas: ? 0 a at 25c. accuracy of sensing zero current flow at 25c, without the effects of temperature. ? 0 a over temperature. accuracy of sensing zero current flow including temperature effects. ? full-scale current at 25c. accuracy of sensing the full-scale current at 25c, without the effects of temperature. ? full-scale current over temperature. accuracy of sensing full- scale current flow including temperature effects. ratiometry . the ratiometric feature means that its 0 a output, v iout(q) , (nominally equal to v cc /2) and sensitivity, sens, are proportional to its supply voltage, v cc . the following formula is used to derive the ratiometric change in 0 a output voltage, v iout(q)rat (%). the ratiometric change in sensitivity, sens r at (%), is defined as: definitions of accuracy characteristics 100 1? [{ [{ v iout _full-scale amperes ? v iout(q) 2 (v iout _1/2 full-scale amperes ? v iout(q) ) 100 v iout _+ full-scale amperes ? v iout(q) v iout(q) ? v iout _?full-scale amperes 100 v iout(q)vcc / v iout(q)5v v cc / 5 v 100 sens vcc / sens 5v v cc / 5 v output voltage versus sensed current accuracy at 0 a and at full-scale current increasing v iout (v) +i p (a) accuracy accuracy acc u racy 25 c o nly acc u racy 25 c o nly a ccuracy 25 c on ly a ccuracy 0 a v ro e ? temp erature average v iout ?i p (a) v ro e ? temp erature v ro e ? temp erature decreasing v iout (v) i p (min) i p (max) full scale high-bandwidth, fast fault response current sensor ic in thermally enhanced package acs709 allegro microsystems, llc 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com
19 definitions of dynamic response characteristics propagation delay (t prop ). the time required for the device output to reflect a change in the primary current signal. propaga- tion delay is attributed to inductive loading within the linear ic package, as well as in the inductive loop formed by the primary conductor geometry. propagation delay can be considered as a fixed time offset and may be compensated. primary current transducer output 90 0 i (%) propagation time, t prop t primary current transducer output 90 0 i (%) response time, t response t primary current transducer output 90 10 0 i (%) rise time, t r t rise time (t r ). the time interval between a) when the device reaches 10% of its full scale value, and b) when it reaches 90% of its full scale value. the rise time to a step response is used to derive the bandwidth of the current sensor ic, in which ?(C3 db) = 0.35 / t r . both t r and t response are detrimentally affected by eddy current losses observed in the conductive ic ground plane. response time (t response ). the time interval between a) when the primary current signal reaches 90% of its final value, and b) when the device reaches 90% of its output corresponding to the applied current. high-bandwidth, fast fault response current sensor ic in thermally enhanced package acs709 allegro microsystems, llc 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com
20 package lf, 24-pin qsop 0.635 bsc 0.25 0.15 0.25 max 1.75 max 8o 0o 1.27 0.41 0.25 bsc 1.04 ref 8.66 0.10 3.91 0.10 0.30 0.20 5.99 0.20 c 0.20 24x seating plane c 0.635 2.30 5.00 0.40 21 24 gauge plane seating plane a c c b a for reference only, not for tooling use (reference jedec mo-137 ae) dimensions in millimeters dimensions exclusive of mold flash, gate burrs, and dambar protrusions exact case and lead configuration at supplier discretion within limits shown b reference pad layout (reference ipc7351 sop63p600x175-24m) all pads a minimum of 0.20 mm from all adjacent pads; adjust as necessary to meet application process requirements and pcb layout tolerances terminal #1 mark area pcb layout reference view standard branding reference view n = device part number t = temperature code lf = (literal) package type a = amperage tlf-aaa lllllllllll nnnnnnnnnnnnn branded face branding scale and appearance at supplier discretion high-bandwidth, fast fault response current sensor ic in thermally enhanced package acs709 allegro microsystems, llc 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com
21 for the latest version of this document, visit our website: www.allegromicro.com copyright ?2008-2016, allegro microsystems, llc the products described herein are protected by u.s. patents: 7,166,807; 7,425,821; 7,573,393; and 7,598,601. allegro microsystems, llc reserves the right to make, from time to time, such departures from the detail specifications as may be required to permit improvements in the performance, reliability, or manufacturability of its products. before placing an order, the user is cautioned to verify that the information being relied upon is current. allegros products are not to be used in any devices or systems, including but not limited to life support devices or systems, in which a failure of allegros product can reasonably be expected to cause bodily harm. the information included herein is believed to be accurate and reliable. however, allegro microsystems, llc assumes no responsibility for its use; nor for any infringement of patents or other rights of third parties which may result from its use. revision history revision revision date description of revision 3 june 6, 2014 added 10bb and 6bb parts 4 february 8, 2016 updated common operating characteristics and supply current in electrical characteristics table high-bandwidth, fast fault response current sensor ic in thermally enhanced package acs709 allegro microsystems, llc 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com

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