HA5340 Datasheet, PDF (8/12 Pages) Intersil Corporation – High Speed, Low Distortion, Precision Monolithic Sample and Hold Amplifier

Semiconductor
HA5340
DESIGN INFORMATION
August 1999
High Speed, Low Distortion, Precision
Monolithic Sample and Hold Amplifier
The information contained in this section has been developed through characterization by Intersil Semiconductor and is for use as applica-
tion and design information only. No guarantee is implied.
Applying the HA-5340
The HA-5340 has the uncommitted differential inputs of an
op amp, allowing the Sample and Hold function to be com-
bined with many conventional op amp circuits. See the Inter-
sil Application Note 517 for a collection of circuit ideas.
Layout
A printed circuit board with ground plane is recommended
for best performance. Bypass capacitors (0.01 to 0.1µF,
ceramic) should be provided from each power supply termi-
nal to the Supply Ground terminal on pin 13.
The ideal ground connections are pin 6 (SIG. Ground)
directly to the system Signal Ground, and pin 13 (Supply
Ground) directly to the system Supply Common.
Hold Capacitor
The HA-5340 includes a 135pF MOS hold capacitor, suffi-
cient for most high speed applications (the Electrical Specifi-
cations section is based on this internal capacitor).
Additional capacitance may be added between pins 7 and
11. This external hold capacitance will reduce droop rate at
the expense of acquisition time, and provide other trade-offs
as shown in the Performance Curves.
The hold capacitor CH should have high insulation resis-
tance and low dielectric absorption, to minimize droop
errors. Teflon®, polystyrene and polypropylene dielectric
capacitor types offer good performance over the specified
operating temperature range.
The hold capacitor terminal (pin 11) remains at virtual
ground potential. Any PC connection to this terminal should
be kept short and ‘‘guarded’’ by the ground plane, since
nearby signal lines or power supply voltages will introduce
errors due to drift current.
®Teflon is a registered Trademark of Dupont Corporation.
Applications
Figure 1 shows the HA-5340 connected as a unity gain non-
inverting amplifier – its most widely used configuration. As
an input device for a fast successive – approximation A/D
converter, it offers very high throughput rate for a monolithic
IC sample/hold amplifier. Also, the HA-5340’s hold step error
is adjustable to zero using the Offset Adjust potentiometer,
to deliver a 12-bit accurate output from the converter.
The HA-5340 output circuit does not include short circuit
protection, and consequently its output impedance remains
low at high frequencies. Thus, the step changes in load cur-
rent which occur during an A/D conversion are absorbed at
the S/H output with minimum voltage error. A momentary
short circuit to ground is permissible, but the output is not
designed to tolerate a short of indefinite duration.
-15V +15V
VIN
S/H CONTROL
H
S
OFFSET
ADJUST
≈ ±15mV
50KΩ
3
45
1
2
14
13
HA-5340
SYSTEM
POWER
GROUND
9 11
CH
135pF
7
HI-774
13 _INPUT
6
SYSTEM
SIGNAL
GROUND
CONVERT
5 _R/C
9 _ANALOG
COMMON
DIGITAL
OUTPUT
FIGURE 1. TYPICAL HA-5340 CONNECTIONS; NONINVERTING UNITY GAIN MODE
NOTE: Pin Numbers Refer to DIP Package Only.
Spec Number 511117-883
7-15