ISL55191 Datasheet, PDF (15/18 Pages) Intersil Corporation – Single and Dual Ultra-Low Noise, Ultra-Low Distortion, Rail-to-Rail, Low Power Op Amp

ISL55191, ISL55291
CURRENT
INPUT
+5VDC
R_F
10kΩ
PARASITIC
L TO R
R_T
R_G-
100
R_SENSE
0.01Ω
R_G+
100Ω
V_REF
+2.5V
ISL55191
IN- V+
FEEDBACK
OUT
IN+ V-
R_REF
10kΩ
CURRENT
INPUT
VOUT
R_L
FIGURE 44. GROUND SIDE CURRENT SENSE AMPLIFIER
Current Sense Application Circuit
The schematic in Figure 44 provides an example of utilizing
the ISL55191 high speed performance with the ground
sensing input capability to implement a single-supply, G = 10
differential low side current sense amplifier. The reference
voltage applied to V_REF (+2.5V) defines the amplifier output
0A current sense reference voltage at one half the supply
voltage level (V_S = +5VDC), and R_SENSE sets the current
sense gain and full scale values. In this example the current
gain is 10A/V over a maximum current range of slightly less
than ±25A with R_SENSE = 0.01Ω. The amplifier V_IO error
(800µV max) and input bias offset current I_IO error (0.7µA)
together contribute less than 10mV (100mA) at the output for
better than 0.2% full scale accuracy.
The amplifier’s high slew rate and fast pulse response make
this circuit suitable for low-side current sensing in PMWM
and motor control applications. The excellent input overload
recovery response enables the circuit to maintain
performance in the presence of parasitic inductance that
cause fast rise and falling edge spikes that can momentarily
overload the input stage of the amplifier.
15
FN6263.1
March 30, 2007