LTC1857 LINEAR [Linear Integrated Systems], LTC1857 Datasheet - Page 19

• Manufacturer Part Number: LTC1857
• Description: 8-Channel, 12-/14-/16-Bit, 100ksps SoftSpan A/D Converters with Shutdown
• Manufacturer: LINEAR [Linear Integrated Systems]

APPLICATIO S I FOR ATIO
LTC1858/LTC1859 can be tied to the analog ground plane.
Placing the bypass capacitor as close as possible to the
power supply pins, the reference and reference buffer output
is very important. Low impedance common returns for
these bypass capacitors are essential to low noise opera-
tion of the ADC, and the foil width for these tracks should
be as wide as possible. Also, since any potential difference
PACKAGE DESCRIPTIO
(.0035 – .010)
NOTE:
1. CONTROLLING DIMENSION: MILLIMETERS
2. DIMENSIONS ARE IN
3. DRAWING NOT TO SCALE
0.09 – 0.25
(.197 – .221)
5.00 – 5.60**
(.022 – .037)
+
–
MILLIMETERS
0.55 – 0.95
(INCHES)
U
CH0
CH1
CH2
CH3
CH4
CH5
CH6
CH7
COM
LTC1857/
LTC1858/
LTC1859
U
MUXOUT
MUXOUT
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
**
*
DIMENSIONS DO NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED .152mm (.006") PER SIDE
DIMENSIONS DO NOT INCLUDE INTERLEAD FLASH. INTERLEAD
FLASH SHALL NOT EXCEED .254mm (.010") PER SIDE
0° – 8°
+
–
(.0256)
W
7.8 – 8.2
10
11 13
0.65
BSC
0.42 ±0.03
U
12
Figure 13. Power Supply Grounding Practice
ADC
ADC
(.009 – .015)
0.22 – 0.38
RECOMMENDED SOLDER PAD LAYOUT
ANALOG GROUND PLANE
TYP
+
–
V
(Reference LTC DWG # 05-08-1640)
28-Lead Plastic SSOP (5.3mm)
REF
U
15
1µF
REFCOMP
G Package
16
10µF
AGND
LTC1857/LTC1858/LTC1859
in grounds between the signal source and ADC appears as
an error voltage in series with the input signal, attention
should be paid to reducing the ground circuit impedance
as much as possible. The digital output latches and the
onboard sampling clock have been placed on the digital
ground plane. The two ground planes are tied together at
the power supply ground connection.
14, 17, 18
AV
LTC1857/LTC1858/LTC1859
DD
19
1.25 ±0.12
5.3 – 5.7
(.002)
0.05
MIN
10µF
0.65 BSC
(.079)
MAX
2.0
DV
DD
20
28
10µF
1 2 3 4 5 6 7 8 9 10 11 12
27
DGND
26
24
25
24
OV
9.90 – 10.50*
(.390 – .413)
23
DD
21
22 21 20 19 18 17 16 15
10µF
1859 F13
SYSTEM
DIGITAL
13
14
G28 SSOP 0204
19
(.291 – .323)
7.40 – 8.20
185789f