CA5160_03 Datasheet, PDF (9/19 Pages) Intersil Corporation – 4MHz, BiMOS Microprocessor Operational Amplifier with MOSFET Input/CMOS Output

CA5160
+7.5V
10kΩ
3
+
0.01µF
7
6
2
BW (-3dB) = 4MHz
SR = 10V/µs
-
4
0.01
µF
-7.5V
2kΩ
0.1µF
2kΩ
25pF
SIMULATED
LOAD
CAPACITANCE
FIGURE 6A. DUAL SUPPLY FOLLOWER
Top Trace: Output
Bottom Trace: Input
FIGURE 6B. SMALL SIGNAL RESPONSE
Top Trace: Output Signal
Center Trace: Difference Signal 5mV/Div.
Bottom Trace: Input Signal
FIGURE 6C. INPUT-OUTPUT DIFFERENCE SIGNAL SHOWING
SETTLING TIME
FIGURE 6. SPLIT SUPPLY VOLTAGE FOLLOWER WITH
ASSOCIATED WAVEFORMS
9 Bit CMOS DAC
A typical circuit of a 9 bit Digital-to-Analog Converter (DAC)
(see Note) is shown in Figure 8. This system combines the
concepts of multiple-switch CMOS ICs, a low cost ladder
network of discrete metal-oxide-film resistors, a CA5160 op
amp connected as a follower, and an inexpensive monolithic
regulator in a simple single power supply arrangement. An
additional feature of the DAC is that it is readily interfaced
with CMOS input logic, e.g., 10V logic levels are used in the
circuit of Figure 8.
The circuit uses an R/2R voltage-ladder network, with the
output-potential obtained directly by terminating the ladder
arms at either the positive or the negative power-supply
terminal. Each CD4007A contains three “inverters”, each
“inverter” functioning as a single-pole double-throw switch to
terminate an arm of the R/2R network at either the positive or
negative power-supply terminal. The resistor ladder is an
assembly of 1% tolerance metal-oxide film resistors. The five
arms requiring the highest accuracy are assembled with series
and parallel combinations of 806,000Ω resistors from the same
manufacturing lot.
A single 15V supply provides a positive bus for the CA5160
follower amplifier and feeds the CA3085 voltage regulator. A
“scale-adjust” function is provided by the regulator output
control, set to a nominal 10V level in this system. The line-
voltage regulation (approximately 0.2%) permits a 9 bit
accuracy to be maintained with variations of several volts in
the supply. The flexibility afforded by the CMOS building
blocks simplifies the design of DAC systems tailored to
particular needs.
Error Amplifier in Regulated Power Supplies
The CA5160 is an ideal choice for error-amplifier service in
regulated power supplies since it can function as an error-
amplifier when the regulated output voltage is required to
approach 0V.
The circuit shown in Figure 9 uses a CA5160 as an error
amplifier in a continuously adjustable 1A power supply. One
of the key features of this circuit is its ability to regulate down
to the vicinity of zero with only one DC power supply input.
An RC network, connected between the base of the output
drive transistor and the input voltage, prevents “turn-on
overshoot”, a condition typical of many operational-amplifier
regulator circuits. As the amplifier becomes operational, this
RC network ceases to have influence on the regulator
performance.
NOTE: “Digital-to-Analog Conversion Using the Intersil CD4007A
CMOS IC”, Application Note AN6080.
9