HCPL-7560 Datasheet, PDF (17/18 Pages) Agilent(Hewlett-Packard) – Optically Isolated Sigma-Delta Modulator

Table 3. Isotek (Isabellenhütte) Four-Terminal Shunt Summary.
Shunt Resistor
Part Number
PBV-R050-0.5
PBV-R020-0.5
PBV-R010-0.5
PBV-R005-0.5
PBV-R002-0.5
Shunt Resistance
Tol.
mΩ
%
50
0.5
20
0.5
10
0.5
5
0.5
2
0.5
Maximum RMS
Current
A
3
7
14
25 [28]
39 [71]
Note: Values in brackets are with a heatsink for the shunt.
Motor Power Range
120 V_ac-440 V_ac
hp
kW
0.8 - 3
0.6 - 2
2-7
0.6 - 2
4 - 14
3 - 10
7 - 25 [8 - 28]
5 - 19 [6 - 21]
11 - 39 [19 - 71] 8 - 29 [14 - 53]
In some applications, however,
supply currents flowing
through the power-supply
return path may cause offset
or noise problems. In this
case, better performance may
be obtained by connecting V_IN+
and V_IN- directly across the
shunt resistor with two
conductors, and connecting
GND1 to the shunt resistor
with a third conductor for the
power-supply return path, as
shown in Figure 19. When
connected this way, both input
pins should be bypassed. To
minimize electromagnetic
interference of the sense
signal, all of the conductors
(whether two or three are
used) connecting the isolated
modulator to the sense resistor
should be either twisted pair
wire or closely spaced traces
on a PC board.
The 39Ω resistor in series with
the input lead (R2) forms a
lowpass anti-aliasing filter
with the 0.01µF input bypass
capacitor (C2) with a 400 kHz
bandwidth. 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 connecting
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.
FLOATING
POSITIVE
SUPPLY
HV+
GATE DRIVE
CIRCUIT
R1
MOTOR
+-
R _SENSE
D1
5.1 V
R2a 39Ω
R2b 39Ω
C1
0.1 µF
C2a C2b
0.01 µF 0.01 µF
V _DD1
V _IN+
V _IN-
GND1
V _DD2
MCLK
MDAT
GND2
HCPL-7560
HV-
Figure 19. Schematic for Three Conductor Shunt Connection.