Datasheet

LT6220/LT6221/LT6222
17
622012fc
For more information www.linear.com/LT6220/LT6221/LT6222
Typical applicaTions
DD Package
8-Lead Plastic DFN (3mm × 3mm)
(Reference LTC DWG # 05-08-1698 Rev C)
and the output of the lower path is:
+OUT = 3 •(2/3 • V
ICM
+ 1/3 • V
OCM
) – 2
• (V
ICM
– V
DIFF
/2)
= 2V
ICM
+ V
OCM
– 2V
ICM
+ V
DIFF
= V
OCM
+ V
DIFF
Note that the input common mode voltage does not appear
in the output as either a common mode or a difference
mode term. However the voltage V
OCM
does appear in
the output terms, and with the same polarity, so it sets
up the output DC level. Also, the differential input voltage
V
DIFF
appears fully at both outputs with opposite polarity,
giving rise to the effective differential gain of 2. Calcula-
tions show that using 1% resistors gives worst-case input
common mode feedthrough better than –31dB, whether
looking at the output common mode or difference mode.
Considering the 6dB of gain, worst-case common mode
rejection ratio is 37dB. (Remember this is assuming 1%
resistors. Of course, this can be improved with more pre
-
cise resistors.) Results achieved on the bench with typical
1% resistors showed 67dB of CMRR at low frequency and
40dB CMRR at 1MHz. Gains other than 2 can be achieved
by setting R3 = α • (R1||R2), R5 = α • R4 and R7 = α • R6
where gain = α.
package DescripTion
Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings.
3.00 ±0.10
(4 SIDES)
NOTE:
1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION OF (WEED-1)
2. DRAWING NOT TO SCALE
3. ALL DIMENSIONS ARE IN MILLIMETERS
4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE
MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE
5. EXPOSED PAD SHALL BE SOLDER PLATED
6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION
ON TOP AND BOTTOM OF PACKAGE
0.40 ±0.10
BOTTOM VIEW—EXPOSED PAD
1.65 ±0.10
(2 SIDES)
0.75 ±0.05
R = 0.125
TYP
2.38 ±0.10
14
85
PIN 1
TOP MARK
(NOTE 6)
0.200 REF
0.00 – 0.05
(DD8) DFN 0509 REV C
0.25 ±0.05
2.38 ±0.05
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED
1.65 ±0.05
(2 SIDES)2.10 ±0.05
0.50
BSC
0.70 ±0.05
3.5 ±0.05
PACKAGE
OUTLINE
0.25 ±0.05
0.50 BSC
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