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Sigma-Delta Modulator. ACPL-7970 Datasheet |
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ACPL-7970
Optically Isolated Sigma-Delta Modulator
Data Sheet
Description
The ACPL-7970 is a 1-bit, second-order sigma-delta (∑-∆)
modulator converts an analog input signal into a high-
speed data stream with galvanic isolation based on optical
coupling technology. The ACPL-7970 operates from a 5 V
power supply with dynamic range of 78 dB with an appro-
priate digital filter. The differential inputs of ±200 mV (full
scale ±320 mV) are ideal for direct connection to shunt
resistors or other low-level signal sources in applications
such as motor phase current measurement.
The analog input is continuously sampled by a means of
sigma-delta over-sampling using an on-board clock. The
signal information is contained in the modulator data, as a
density of ones with data rate of 10 MHz, and the data are
encoded and transmitted across the isolation boundary
where they are recovered and decoded into high-speed
data stream of digital ones and zeros. The original signal
information can be reconstructed with a digital filter. The
serial interface for data and clock has a wide supply range
of 3 V to 5.5 V.
Combined with superior optical coupling technology,
the modulator delivers high noise margins and excellent
immunity against isolation-mode transients. With 0.5 mm
minimum distance through insulation (DTI), the ACPL‑7970
provides reliable reinforced insulation and high working
insulation voltage, which is suitable for fail-safe designs.
This outstanding isolation performance is superior to
alternatives including devices based on capacitive- or
magnetic-coupling with DTI in micro-meter range. Offered
in a DIP-8 package, the isolated ADC delivers the reliabil-
ity, small size, superior isolation and over-temperature
performance motor drive designers need to accurately
measure current at much lower price compared to tradi-
tional current transducers.
The external clock version modulator ACPL-796J (SO-16
package) is also available.
Features
• 10 MHz internal clock
• 1-bit, second-order sigma-delta modulator
• 16 bits resolution no missing codes (12 bits ENOB)
• 78 dB SNR
• 6 mV/°C maximum offset drift
• ±1% maximum gain error
• Internal reference voltage
• ±200 mV linear range with single 5 V supply (±320 mV
full scale)
• 3 V to 5.5 V wide supply range for digital interface
• -40° C to +105° C operating temperature range
• 25 kV/ms common-mode transient immunity
• Safety and regulatory approvals:
– IEC/EN/DIN EN 60747-5-5: 891 Vpeak working
insulation voltage
– UL 1577: 5000 Vrms/1min isolation voltage
– CSA: Component Acceptance Notice #5
Applications
• Motor phase and rail current sensing
• Power inverter current and voltage sensing
• Industrial process control
• Data acquisition systems
• General purpose current and voltage sensing
• Traditional current transducer replacements
Functional Block Diagram
VDD1
VIN+
VIN–
Σ-∆
MODULATOR/
ENCODER
LED
DRIVER
CLK
DECODER
SHIELD
VDD2
MCLK
MDAT
GND1
VREF
GND2
CAUTION: It is advised that normal static precautions be taken in handling and assembly
of this component to prevent damage and/or degradation which may be induced by ESD.
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Pin Configuration and Descriptions
VDD1
VIN+
VIN–
GND1
1
2
3
4
ACPL-7970
8 VDD2
7 MCLK
6 MDAT
5 GND2
Figure 1. Pin configuration.
Table 1. Pin descriptions.
Pin No.
1
2
3
4
5
6
7
8
Symbol
VDD1
VIN+
VIN–
GND1
GND2
MDAT
MCLK
VDD2
Description
Supply voltage for signal input side (analog side), relative to GND1
Positive analog input, recommended input range ±200 mV
Negative analog input, recommended input range ±200 mV (normally connected to GND1)
Supply ground for signal input side
Supply ground for data/clock output side (digital side)
Modulator data output
Modulator clock output
Supply voltage for data output side, relative to GND2
Table 2. Ordering Information
ACPL-7970 is UL recognized with 5000 Vrms/1 minute rating per UL 1577.
Part number
ACPL-7970
Option (RoHS
Compliant)
-000E
-300E
-500E
Package
300 mil
DIP-8
Surface
Mount
X
X
Gull Wing Tape & Reel
X
XX
IEC/EN/DIN EN
60747-5-5
X
X
X
Quantity
50 per tube
50 per tube
1000 per reel
To order, choose a part number from the part number column and combine with the desired option from the option
column to form an order entry.
Example:
ACPL-7970-500E to order product of Surface Mount package in Tape and Reel packaging with IEC/EN/DIN EN 60747-5-5
Safety Approval and RoHS compliance.
Option datasheets are available. Contact your Avago sales representative or authorized distributor for information.
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Package Outline Drawings
Standard DIP Package
9.80 ± 0.25
(0.386 ± 0.010)
87
65
A 7970
YYWW
DATE CODE
1.19 (0.047) MAX.
12 34
1.78 (0.070) MAX.
Dimensions in millimeters and (inches).
Note:
Floating lead protrusion is 0.5 mm (20 mils) max.
7.62 ± 0.25
(0.300 ± 0.010)
6.35 ± 0.25
(0.250 ± 0.010)
3.56 ± 0.13
(0.140 ± 0.005)
4.70 (0.185) MAX.
1.080 ± 0.320
(0.043 ± 0.013)
0.51 (0.020) MIN.
2.92 (0.115) MIN.
0.65 (0.025) MAX.
2.54 ± 0.25
(0.100 ± 0.010)
5˚ TYP.
0.20 (0.008)
0.33 (0.013)
Note: Initial or continued variation in the color of the white mold compound is normal and does not affect device performance or reliability.
Figure 2.
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