Datasheet

V
REF
¶
100 k:
V
REFA
V
REFB
100 k:
(6V Max)
-0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7
0
2
4
6
8
10
12
14
VOUT (V)
VSENSE (V)
V
CC
> 14V
V
REF
= 1.2V
V
CC
= +4.5V to +76V
C1
0.1 PF
V
OUT
To Load
R
SENSE
I
SENSE
ADC
RSN
RSP
REFA
REFB
GND
LMP8481
LM4140ACM-1.2
V
IN
+
V
IN
-
V
REF
C2
0.1 PF
V
SENSE
LMP8480, LMP8481
www.ti.com SNVS829A –JUNE 2012–REVISED AUGUST 2012
Figure 10. Bi-Directional current sensing using LMP8481
The V
REFA
and V
REFB
pins set the zero reference point. The output “zero” reference point is set by applying a
voltage to the REFA and/or REFB pins. See the BI-DIRECTIONAL OPERATION (LMP8481 ONLY) section
below. REFA AND REFB PINS (LMP8481 Only) below shows the output transfer function with a 1.2V reference
applied to the Gain-of-20 option
Figure 11. Bi-Directional Transfer Function using 1.2V Reference Voltage
REFA AND REFB PINS (LMP8481 Only)
The voltage applied to the V
REFA
and V
REFB
pins controls the output zero reference level.
The reference inputs consist of a pair of divider resistors with equal values to a common summing point, V
REF
’,
as shown in Figure 16 below.
Figure 12. V
REF
Input Resistor Network
V
REF
’ is the voltage at the resistor tap point that will be directly applied to the output as an offset.
V
OUT
= ( (V
RSP
– V
RSN
) * Av ) + V
REF
’ (2)
Where:
V
REF
’ = V
REFA
= V
REFB
(Equal Inputs) (3)
OR (4)
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