Avago Technologies ACPL-224-500E - Manual (Page 57)

AV02-4387EN 54 Avago Technologies
Isolated A/D Converter for Phase Current Sensing
Motor Control Applications
Performance of Circuit
• Resolution due to linearity: 12
bits at t
DELAY
= 18 µs, 14 bits at
t
DELAY
= 94 µs
• Common­mode transient rejec-
tion: dV/dt = 15 kV/ µs @ V
CM
=
1500 V
• Signal­to­Noise: SNR = 62 dB
(minimum)
• Regulatory Isolation Ratings: V
ISO
= 3750 V (per UL 1577), V
IORM
=
848 V; V
IOTM
= 6000 V
• Input Offset Drift: 4 µV / °C (typi-
cal)
• Reference Voltage Tolerance:
±4% (±1% within shipment tube)
Benefits
• Integrated analog­to­digital con-
verter means fewer components
required.
• High common­mode transient
rejection ensures no corruption
of data.
• Low gain temperature­coeffi-
cient and offset voltage ensure
high accuracy measurements.
References
1) HCPL-7860/x870 Technical Data
2) High precision current sensing
resistor suppliers: Dale in USA;
Isabellenhutte in Germany; and
PCN in Japan
Description
The HCPL-7860 Isolated Modulator
and the HCPL-x870 Digital Inter-
face IC together form an isolated
programmable two-chip analog-to-
digital converter. The isolated mod-
ulator allows direct measurement of
motor phase currents in power in-
verters while the digital interface IC
can be programmed to optimize the
conversion speed and resolution.
+ -
MOTOR
HV-
HV+
R SENSE
FLOATING
POSITIVE
SUPPLY
GATE DRIVE
CIRCUIT
V
DD1
V IN+
V IN-
GND1
V
DD2
MCLK
MDAT
GND2
CDAT SCLK
CCLK V DD
CLAT CHAN
MCLK1 SDAT
MDAT1 CS
MCLK2 THR1
MDAT2 OVR1
GND RESET
+ 5 V
HCPL-7860
TO
CONTROL
CIRCUIT
C3
0.1 µF
C1
0.1 µF
C2
0.01 µF
R2 39 Ω
R1
D1
5.1 V
HCPL-X870