AD8203YRZ Analog Devices Inc, AD8203YRZ Datasheet - Page 16

• Manufacturer Part Number: AD8203YRZ
• Description: IC,Differential Amplifier,SINGLE,BIPOLAR,SOP,8PIN,PLASTIC
• Manufacturer: Analog Devices Inc
• Type: Single Supplyr

Specifications of AD8203YRZ

• Amplifier Type: Differential
• Number Of Circuits: 1
• Slew Rate: 0.330 V/µs
• Gain Bandwidth Product: 60kHz
• Current - Input Bias: 40nA
• Voltage - Input Offset: 1000µV
• Current - Supply: 250µA
• Voltage - Supply, Single/dual (±): 3.5 V ~ 12 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Bandwidth: 60 kHz
• Common Mode Rejection Ratio: 82
• Current, Input Bias: 40 nA
• Current, Supply: 0.25 mA
• Package Type: SOIC-8
• Resistance, Input: 320 Kilohms (Differential), 160 Kilohms (Common-Mode)
• Temperature, Operating, Range: -40 to +125 °C
• Voltage, Gain: 14 V/V
• Voltage, Input: -6 to +30 V
• Voltage, Input Offset: -1 to +1 mV
• Voltage, Noise: 300 nV/sqrt Hz
• Voltage, Output Swing: 0.02 to 4.8 V
• Voltage, Supply: 3.5 to 12 V
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Output Type: -
• Current - Output / Channel: -
• -3db Bandwidth: -
• Lead Free Status / Rohs Status: RoHS Compliant part Electrostatic Device

AD8203
HIGH LINE CURRENT SENSING WITH LPF AND
GAIN ADJUSTMENT
Figure 49 is another refinement of Figure 2, including gain
adjustment and low-pass filtering.
BATTERY
A power device that is either on or off controls the current in
the load. The average current is proportional to the duty cycle
of the input pulse and is sensed by a small value resistor. The
average differential voltage across the shunt is typically 100 mV,
although its peak value is higher by an amount that depends on
the inductance of the load and the control frequency. The
common-mode voltage, conversely, extends from roughly 1 V
above ground for the on condition to about 1.5 V above the
battery voltage for the off condition. The conduction of the
clamping diode regulates the common-mode potential applied
to the device. For example, a battery spike of 20 V may result in
an applied common-mode potential of 21.5 V to the input of
the devices.
To produce a full-scale output of 4 V, a gain ×40 is used, adjust-
able by ±5% to absorb the tolerance in the shunt. There is
sufficient headroom to allow 10% overrange (to 4.4 V). The
roughly triangular voltage across the sense resistor is averaged
40log (f
Figure 48. Comparative Responses of 1-Pole and 2-Pole Low-Pass Filters
2
/f
1
)
14V
NC = NO CONNECT
CLAMP
DIODE
Figure 49. High Line Current Sensor Interface;
A 1-POLE FILTER, CORNER f
A 2-POLE FILTER, CORNER f
THE SAME ATTENUATION –40log (f
AT FREQUENCY f
Gain = ×40, Single-Pole Low-Pass Filter
FREQUENCY
POWER
DEVICE
20dB/DECADE
4-TERM
SHUNT
f
1
INDUCTIVE
LOAD
COMMON
2
2
/f
1
+IN
–IN
f
AD8203
2
GND
+V
5V
1
2
, AND
, HAVE
S
NC
A1
40dB/DECADE
2
C
5% CALIBRATION RANGE
f
(0.22μF FOR f
/f
C
OUT
1
A2
(Hz) = 0.767Hz/C(μF)
)
V
NULL
f
2
OS/IB
2
/f
1
C
133kΩ
20kΩ
= 3.6Hz)
OUT
4V/AMP
Rev. B | Page 16 of 20
by a 1-pole low-pass filter, shown in
frequency of 3.6 Hz, which provides about 30 dB of attenuation
at 100 Hz. A higher rate of attenuation can be obtained using a
2-pole filter with f
this circuit uses two separate capacitors, the total capacitance is
less than half that needed for the 1-pole filter.
DRIVING CHARGE REDISTRIBUTION ADCS
When driving CMOS ADCs, such as those embedded in popu-
lar microcontrollers, the charge injection (ΔQ) can cause a
significant deflection in the output voltage of the AD8203.
Though generally of short duration, this deflection may persist
until after the sample period of the ADC has expired due to the
relatively high open-loop output impedance (21 kΩ) of the
AD8203. Including an R-C network in the output can signifi-
cantly reduce the effect. The capacitor helps to absorb the
transient charge, effectively lowering the high frequency output
impedance of the AD8203. For these applications, the output
signal should be taken from the midpoint of the
R
Since the perturbations from the analog-to-digital converter are
small, the output impedance of the AD8203 appears to be low. The
transient response, therefore, has a time constant governed by the
product of the two LAG components, C
shown in Figure 51, this time constant is programmed at approxi-
mately 10 μs. Therefore, if samples are taken at several tens of
microseconds or more, there is negligible charge stack-up.
BATTERY
LAG
to C
4
+IN
–IN
LAG
Figure 51. Recommended Circuit for Driving CMOS A/D
5V
14V
NC = NO CONNECT
CLAMP
DIODE
combination, as shown in Figure 51.
7
A2
10kΩ
10kΩ
C
Figure 50. 2-Pole Low-Pass Filter
AD8203
POWER
DEVICE
= 20 Hz, as shown in Figure 50. Although
4-TERM
SHUNT
2
5
INDUCTIVE
LOAD
COMMON
R
1kΩ
LAG
+IN
–IN
0.01μF
C
Figure 49
LAG
AD8203
GND
+V
5V
LAG
S
× R
NC
A1
C
f
(0.05μF FOR f
LAG
C
MICROPROCESSOR
OUT
A2
(Hz) = 1/C(μF)
, set with a corner
. For the values
93kΩ
A/D
C
C
301kΩ
50kΩ
= 20Hz)
OUTPUT