ACS760ELF-20B データシートの表示（PDF） - Allegro MicroSystems

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ACS760ELF-20B

12 V High-Side Hot-Swap Hall Effect Based Current Monitor

Allegro MicroSystems 

ACS760ELF-20B 12 V High-Side Hot-Swap Hall Effect Based Current Monitor

Soft Start and Fault Characteristics

Gate turn on rise time, tGR. Set by external capacitance, CG, on

the CG pin, such that CG = 7.5 × tGR , where CG is in μF and tGR

is rise time in seconds. For example, a 3.9 μF capacitor connected

from the CG pin to GND (without an output load) will yield a

rise time of approximately 500 ms: CG ≅ 7.5 × 0.5 s = 3.75 μF,

≅ 3.9 μF (a common capacitor value).

When the CG pin is kept open, the ACS760 has a minimum tGR

of 1 ms typical.

IPF fault signal delay, tIPF. This is the delay from high current

level fault sense to the start of turn-off of the external MOSFET

S1 turn-off. Set by external capacitance, COCD, on the OCDLY

pin, such that COCD = 5.17 × trOCD ; where COCD is in μF and

trOCD is rise time in seconds.

When the OCDLY pin is kept open, the IC has a minimum fault

delay, tIPFLmax, of 8 μs maximum.

Load power fault signal delay, tPFL. This is the delay from

maximum power level fault, PF(th), sense to the start of external

MOSFET S1 turn-off. Set by external capacitance, COPD, on the

OPDLY pin, such that COPD = 5.17 × trOPD ; where COPD is in μF

and trOPD is rise time in seconds.

The IC has a minimum fault delay when the OPDLY pin kept

open of 10 μs typical.

IPF fault current setting, IPF. The IPF upper trip level may be

set by using a resistor between the ISET pin and GND, such that

RSET = 104 (0.4 + 0.065 × IPF), where IPF is in A and RSET in Ω.

Accuracy Characteristics

Sensitivity, Sens. The change in sensor output in response to a

1 A change through the primary conductor. Sens is the product of

the magnetic circuit sensitivity (G/A) and the linear IC amplifier

gain (mV/G). The linear IC amplifier gain is trimmed at Allegro

final test to optimize the sensitivity (mV/A) for the full-scale cur-

rent range of the device.

Noise, VNOISE(PP). The product of the linear IC amplifier gain

(mV/G) and the noise floor for the Allegro Hall effect linear IC.

Dividing the noise (mV) by the sensitivity (mV/A) provides the

smallest current that the device is able to resolve.

Nonlinearity, ELIN. The linearity of the VIOUT signal is the

degree to which the voltage output from the sensor varies in

direct proportion to the primary sensed current, through its full-

scale amplitude. Nonlinearity reveals the maximum deviation in

the slope of the device transfer function compared to the slope of

the ideal transfer curve for this transducer. The following equa-

tion is used to derive the linearity:

{ [ 100

1–

(VIOUT_full-scale amperes –VIOUT(Q) )

2 (VIOUT_half-scale amperes – VIOUT(Q))

Zero Current Output Voltage, VIOUT(Q). The output of the sen-

sor when the primary current, IP, is 0 A. Variation in VIOUT(Q) can

be attributed to the resolution of the Allegro linear IC quiescent

voltage trim and thermal drift.

VIOUT Total Error, ETOT. The maximum percentage deviation

of the actual output from its ideal value.

Dynamic Response Characteristics

Propagation delay, tPROP. The time required for the sensor

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.

I (%)

Primary Current

90

Transducer Output

0

t

Propagation Time, tPROP

Response time, tRESPONSE. The time interval between a) when

the primary current signal reaches 90% of its final value, and b)

when the sensor reaches 90% of its output corresponding to the

applied current.

I (%)

90

Primary Current

Transducer Output

0

t

Response Time, tRESPONSE

Rise time (tr). The time interval between a) when the sensor

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, in which ƒ(–3 dB) =

0.35 / tr. Both tr and tRESPONSE are detrimentally affected by eddy

current losses observed in the conductive IC ground plane.

I (%)

90

Primary Current

Transducer Output

10

0

t

Rise Time, tr

Allegro MicroSystems, Inc.

7

115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036 (508) 853-5000

www.allegromicro.com

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