LTC1052CH Linear Technology, LTC1052CH Datasheet - Page 8

• Manufacturer Part Number: LTC1052CH
• Description: LOW NOISE CHOPPER STAB OA
• Manufacturer: Linear Technology
• Series: LTCMOS™r

Specifications of LTC1052CH

• Amplifier Type: Chopper (Zero-Drift)
• Number Of Circuits: 1
• Slew Rate: 4 V/µs
• Gain Bandwidth Product: 1.2MHz
• Current - Input Bias: 1pA
• Voltage - Input Offset: 0.5µV
• Current - Supply: 1.7mA
• Voltage - Supply, Single/dual (±): 4.75 V ~ 16 V, ±2.38 V ~ 8 V
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Through Hole
• Package / Case: TO-5-8
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Output Type: -
• Current - Output / Channel: -
• -3db Bandwidth: -

LTC1052/LTC7652
APPLICATIO S I FOR ATIO
EXTERNAL CAPACITORS
C
and-hold circuit. The important capacitor characteristics
are leakage current and dielectric absorption. A high
quality film-type capacitor such as mylar or polypropylene
provides excellent performance. However, low grade
capacitors such as ceramic are suitable in many
applications.
Capacitors with very high dielectric absorption (ceramic)
can take several seconds to settle after power is first
turned on. This settling appears as clock ripple on the
output and, as the capacitor settles, the ripple gradually
disappears. If fast settling after power turn-on is
important, mylar or polypropylene is recommended.
Above 85°C, leakage, both from the holding capacitors
and the printed circuit board, becomes important. To
maintain the capabilities of the LTC1052 it may be
necessary to use Teflon™ capacitors and Teflon standoffs
when operating at 125°C (see Achieving Picoampere/
Microvolt Performance).
C
to 1.0µF. All specifications are guaranteed with 0.1µF and
the broadband noise (refer to Typical Performance Char-
acteristics) is only very slightly degraded with 0.1µF.
Output clock ripple is not present for capacitors of 0.1µF
or greater at any temperature.
THEORY OF OPERATIO
8
EXTA
EXTA
+ IN
– IN
and C
and C
S1
EXTB
EXTB
are the holding elements of a sample-
are normally in the range of 0.1µF
+
–
U
+
–
g
g
m1
m6
U
l
1
l
3
+
–
–
W
l
2
R
V
δl
L1
U
REF
Figure 1b. LTC1052 Block Diagram
S3
g
m2
U
g
m3
Sampling Cycle
R
L2
S2
On competitive devices, connecting C
V
have eliminated this problem on the LTC1052. On the
14-pin LTC1052 and 8-pin LTC7652, the capacitors can
be returned to V
performance.
ACHIEVING PICOAMPERE/MICROVOLT PERFORMANCE
Picoamperes
In order to realize the picoampere level of accuracy of the
LTC1052, proper care must be exercised. Leakage
currents in circuitry external to the amplifier can
significantly degrade performance. High quality insulation
should be used (e.g., Teflon, Kel-F); cleaning of all
insulating surfaces to remove fluxes and other residues
will probably be necessary—particularly for high
temperature performance. Surface coating may be
necessary to provide a moisture barrier in high humidity
environments.
Board leakage can be minimized by encircling the input
connections with a guard ring operated at a potential
close to that of the inputs: in inverting configurations, the
guard ring should be tied to ground; in noninverting
Teflon is a trademark of Dupont.
–
C
C
EXT B
causes an increase in amplifier noise. Design changes
EXT A
C1
V
–
g
m4
–
or C
RETURN
+
–
+
C2
R
L4
with no change in noise
g
m5
LTC1052/7652 • TO02
EXTA
and C
R
V
L5
OUT
EXTB
1052fa
to