LTC2436-1IGN Linear Technology, LTC2436-1IGN Datasheet - Page 20

• Manufacturer Part Number: LTC2436-1IGN
• Description: IC CONV A/D 16B 2CH DIFF 16SSOP
• Manufacturer: Linear Technology

Specifications of LTC2436-1IGN

• Number Of Bits: 16
• Sampling Rate (per Second): 6.8
• Data Interface: MICROWIRE™, Serial, SPI™
• Number Of Converters: 1
• Power Dissipation (max): 1mW
• Voltage Supply Source: Single Supply
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 16-SSOP (0.150", 3.90mm Width)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

APPLICATIO S I FOR ATIO
LTC2436-1
period. Thus, for settling errors of less than 1LSB, the
driving source impedance should be chosen such that
14.3 s/11 = 1.3 s. When an external oscillator of fre-
quency f
for a settling error of less than 1LSB,
Input Current
If complete settling occurs on the input, conversion re-
sults will be unaffected by the dynamic input current. An
incomplete settling of the input signal sampling process
may result in gain and offset errors, but it will not degrade
the INL performance of the converter. Figure 12 shows the
mathematical expressions for the average bias currents
flowing through the IN
sampling charge transfers when integrated over a sub-
stantial time period (longer than 64 internal clock cycles).
The effect of this input dynamic current can be analyzed
using the test circuit of Figure 13. The C
includes the LTC2436-1 pin capacitance (5pF typical) plus
the capacitance of the test fixture used to obtain the results
shown in Figures 14 and 15. A careful implementation can
bring the total input capacitance (C
thus achieving better performance than the one predicted
20
EOSC
SWITCHING FREQUENCY
f
f
is used, the sampling period is 2/f
SW
SW
V
V
I
V
V
I
REF
I
REF
REF
REF
I
IN
IN
IN
IN
= 69.900Hz INTERNAL OSCILLATOR (F
= 0.5 • f
+
+
–
–
+
+
–
–
U
V
V
EOSC
CC
CC
+
V
V
EXTERNAL OSCILLATOR
I
I
I
I
LEAK
LEAK
LEAK
LEAK
CC
CC
and IN
U
I
I
I
I
LEAK
LEAK
LEAK
LEAK
–
R
R
R
R
pins as a result of the
IN
SW
SW
SW
SW
W
20k
20k
20k
20k
Figure 12. LTC2436-1 Equivalent Analog Input Circuit
+ C
(TYP)
(TYP)
(TYP)
(TYP)
PAR
O
= LOW OR HIGH)
0.18/f
) closer to 5pF
PAR
24361 F12
U
EOSC
capacitor
EOSC
C
18pF
(TYP)
and,
.
EQ
I IN
I IN
I REF
I REF
R
R
where
V
V
V
V
REF
REFCM
IN
INCM
EQ
EQ
Figure 14. +FS Error vs R
IN
AVG
AVG
: :
3 97
REF
0 555 10
AVG
.
AVG
V
V
.
IN
INCM
INCM
M
REF
IN
V
IN
2
V
1 5
IN
REF
.
IN
INTERNAL OSCILLATOR
+ 0.5V
– 0.5V
1 5
Figure 13. An RC Network at IN
3
2
1
0
.
2
12
V
0 5
INCM
REF
0 5
V
1
.
V
.
REF
INCM
V
/
V
REF
REF
IN
IN
F
T
REF
IN
IN
O
A
f
CC
R
EOSC
0 5
+
–
R
= GND
= 25 C
0 5
EQ
.
+
= 5V
= 2.5V
–
EQ
.
= 5V
V
V
REFCM
= 5V
= GND
INCM
V
V
EXTERNAL OSCILLATOR
R
10
C
REFCM
INCM
R
EQ
IN
R
R
EQ
C
SOURCE
SOURCE
IN
C
= 0.001 F
C
IN
V
= 100pF
IN
REFCM
V
= 0.01 F
REFCM
= 0pF
R
100
SOURCE
SOURCE
50
Hz
V
REF
V
C
C
/
REF
( )
60
IN
IN
V
1k
IN
2
V
Hz Notch F
R
IN
2
at IN
EQ
R
EQ
10k
C
C
+
PAR
PAR
20pF
20pF
or IN
+
O
24361 F14
and IN
LOW
100k
–
IN
IN
LTC2436-1
(Small C
+
–
–
24361 F13
IN
)
24361f