ACPL-C797-500E Avago Technologies US Inc., ACPL-C797-500E Datasheet - Page 16

• Manufacturer Part Number: ACPL-C797-500E
• Description: Isolated Sigma-Delta, T/R+IEC+LF
• Manufacturer: Avago Technologies US Inc.
• Series: -r
• Type: Sigma-Delta Modulatorr

Specifications of ACPL-C797-500E

• Voltage - Isolation: 5000Vrms
• Input Type: DC
• Voltage - Supply: 3 V ~ 5.5 V, 4.5 V ~ 5.5 V
• Operating Temperature: -40°C ~ 105°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (0.268", 6.81mm Width)
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

The resistor R2 in series with the input lead forms a low
pass anti-aliasing filter with the input bypass capacitor
C2. The resistor performs another important function
as well; it dampens any ringing which might be present
in the circuit formed by the shunt, the input bypass
capacitor, and the inductance of wires or traces connect-
ing the two. Undamped ringing of the input circuit near
the input sampling frequency can alias into the baseband
producing what might appear to be noise at the output
of the device.
Figure 21. Schematic for three conductor shunt connection
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Data subject to change. Copyright © 2005-2010 Avago Technologies. All rights reserved.
AV02-2581EN - August 20, 2010
MOTOR
+
R
SENSE
–
HV+
HV –
CIRCUIT
DRIVE
GATE
R2a 2.2 :
R2b 2.2 :
FLOATING
POSITIVE SUPPLY
5.1 V
D1
GND1
C1a 1 PF
R1
C1b 0.1 PF
C2
100 nF
www.avagotech.com
V
V
V
GND1
DD1
IN +
IN –
ISOLATION
ACPL-C797
Voltage Sensing
The ACPL-C797 can also be used to isolate signals with
amplitudes larger than its recommended input range
with the use of a resistive voltage divider at its input. The
only restrictions are that the impedance of the divider be
relatively small (less than 1 k:) so that the input resistance
(24 k:) and input bias current (0.3 PA) do not affect the
accuracy of the measurement. An input bypass capacitor
is still required, although the damping resistor is not
(the resistance of the voltage divider provides the same
function). The low-pass filter formed by the divider resis-
tance and the input bypass capacitor may limit the achiev-
able bandwidth. To obtain higher bandwidth, the input
bypass capacitor (C2) can be reduced, but it should not be
reduced much below 1000 pF to maintain adequate input
bypassing of the isolated modulator.
BARRIER
MDAT
MCLK
GND2
V
DD2
ISOLATED
5 V/3.3 V
GND2
NON-
C3a
0.1 PF
C3b
1 PF