NE5537N NXP Semiconductors, NE5537N Datasheet - Page 7

• Manufacturer Part Number: NE5537N
• Manufacturer: NXP Semiconductors

Specifications of NE5537N

• Number Of Sample And Hold Elements: 1
• Power Supply Requirement: Dual
• Single Supply Voltage (typ): Not RequiredV
• Single Supply Voltage (min): Not RequiredV
• Single Supply Voltage (max): Not RequiredV
• Operating Temperature Classification: Commercial
• Mounting: Through Hole
• Package Type: PDIP
• Lead Free Status / RoHS Status: Compliant

Philips Semiconductors
off (switch opens) and the “stored analog memory” information on
the external capacitor (Pin 6) is loaded down by an operational
amplifier connected in the unity gain non-inverting configuration.
This input impedance of this amplifier is effectively:
where
Therefore, the higher the open-loop gain of the second operational
amplifier, the larger the effective loading on the capacitor. The larger
the load, the lower the “leakage” current and the better the droop
characteristics.
In actuality, the amplifiers are designed with special leakage current
cancellation circuits along with FET input devices. The leakage
current cancellation circuits give better high temperature operation.
(Remember that the FET amplifiers double in required bias current
for every 10 degree increase in junction temperature.)
Sampling time for the NE5537 is less than 10 s (measured to 0.1%
of input signal). Leakage current is 6 pA at a rate output load of
2 k .
2001 Aug 03
Sample-and-hold amplifier
R = R
R = Effective input impedance
R
A
A = AC loop gain
V
NOTE:
OUT
IN
OL
= Open-loop input impedance
= Open-loop gain
IN
(A
V IN x
OL
) / (1 + 1/A)
256
1
(20 D 0
V
2 1 D 1
ANALOG INPUT 1
ANALOG INPUT 2
ANALOG INPUT 3
ANALOG INPUT 4
IN
CONTROL 1
CONTROL 2
CONTROL 3
CONTROL 4
2 7 D 7 ) Equation 1
NE5537
Figure 6. Multiplying DAC Application
SD5000
SUBSTRATE
Figure 7. Analog Data Multiplexing
5k
+VREF
5008/DAC-08
D0-D7
7
IN
circuit is used to supply a “variable” reference to the digital-to-analog
BASIC APPLICATIONS
Multiplying DAC
As depicted in the block diagram of Figure 6, the sample-and-hold
converter. As the input reference varies, the output will change in
accordance with Equation 1, shown in Figure 6.
Varying the input signal reference level can aid the system in
performing both compression and expansion operations. The
multiplying DACs used are the Philips Semiconductors NE/SE5008;
however, if the rate of change of the reference variation is kept slow
enough, a microprocessor-compatible DAC can be incorporated,
such as the NE5018 or the NE5020.
DATA ACQUISITION SYSTEMS
As mentioned earlier, the designer may wish to operate on several
different segments of an “analog” signal; however, he is limited by
the fact that only one analog-to-digital converter channel is available
to him. Figure 7 shows the means by which a multiplexing system
may be accomplished.
NE5537
SUCCESSIVE APPROXIMATION
(NE5034, NE5037)
or INTEGRATING TYPE ADC
CONVERTER
530
A/D
5k
SL00347
D
D
V
0
7
OUT
NE5537
Product data
SL00348