5420AMZ Ver la hoja de datos (PDF) - Renesas Electronics
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Fabricante
5420AMZ
Renesas Electronics
5420AMZ Datasheet PDF : 9 Pages
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CA5420A
Typical Applications
Picoammeter Circuit
The exceptionally low input current (typically 0.2pA) makes the
CA5420A highly suited for use in a picoammeter circuit. With only
a single 10GΩ resistor, this circuit covers the range from ±1.5pA.
Higher current ranges are possible with suitable switching
techniques and current scaling resistors. Input transient protection
is provided by the 1MΩ resistor in series with the input. Higher
current ranges require that this resistor be reduced. The 10MΩ
resistor connected to pin 2 of the CA5420A decouples the
potentially high input capacitance often associated with lower
current circuits and reduces the tendency for the circuit to oscillate
under these conditions.
10GΩ
1MΩ
10MΩ
10pF
+1.5V
2-
7
CA5420A 6
500 to 0 to 500
µA
M
3+
4
5
1
BATTERY
RETURNS
10kΩ
-1.5V
±50pA
±15pA
±5pA
±1.5pA
1.5kΩ
1.5kΩ
1%
1kΩ
430Ω
1%
150Ω
1%
11kΩ
68Ω
1%
High Input Resistance Voltmeter
Advantage is taken of the high input impedance of the CA5420A in
a high input resistance DC voltmeter. Only two 1.5V “AA” type penlite
batteries power this exceedingly high-input resistance (>1,000,
000M) DC voltmeter. Full-scale deflection is ±500mV, ±150mV,
and ±15mV. Higher voltage ranges are easily added with external
input voltage attenuator networks.
The meter is placed in series with the gain network, thus
eliminating the meter temperature coefficient error term.
Supply current in the standby position with the meter
undeflected is 300µA. At full-scale deflection this current rises to
800µA. Carbon-zinc battery life should be in excess of 1,000
hours.
+1.5V
22MΩ
3
10MΩ
+
7
CA5420A
500 to 0 to 500
µA
6
M
100pF
2-
4
±500mV 1.5kΩ
5
1
10kΩ
BATTERY
RETURNS
±150mV
1.5kΩ
1%
1kΩ
430Ω
±50mV 1%
-1.5V
150Ω
±15mV 1%
1.1kΩ
68Ω
1%
FIGURE 2. PICOAMMETER CIRCUIT
FIGURE 3. HIGH INPUT RESISTANCE VOLTMETER
Typical Performance Curves
1.0
0.8
TA = +25°C
RL = 100k
0.6
0.4
0.2
0
-0.2
-0.4
-0.6
-0.8
-1.0
01
VO-
VO +
VICR-
VICR+
5
10
15
SUPPLY VOLTAGE (V)
FIGURE 4. OUTPUT VOLTAGE SWING AND COMMON MODE INPUT
VOLTAGE RANGE vs SUPPLY VOLTAGE
10
TA = +25°C
V- = 0V
V+ = 2V
100 V+ = 5V
V+ = 10V
V+ = 20V
1000
0.001
0.1
1
10
LOAD (SOURCING) CURRENT (mA)
FIGURE 5. OUTPUT VOLTAGE vs LOAD SOURCING CURRENT
FN1925 Rev 9.00
February 11, 2015
Page 6 of 9
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