QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 591
EVALUATION CARD FOR THE LT1490A IN THE DFN PACKAGE
LT1490ACDD
DESCRIPTION
Demonstration circuit 591 simplifies the evaluation of
the LT1490ACDD op amp in the tiny, 3mm
×
3mm, DFN
(Dual in-line,
Flat, No-leads)
chip-scale package. Electri-
cal performance of this LT1490 is the same as previous
versions. This version is only a packaging enhancement.
An evaluation circuit can easily be built on this board
without handling the tiny DFN device. Pads are provided
for adding external components and holes are available
for jumpers, signal I/O and supply wires. Supply bypass
capacitors are already on the board. Alternatively adding
two 4-pin headers (0.1" spacing) converts the board to a
standard 8-pin DIP format for use with a socket on a
second circuit board.
The backside of this evaluation board is void of metal to
allow wiring into an existing system with the board rest-
ing on top of other components.
About the LT1490ACDD
The LT1490 is a Dual Over-The-Top Micropower Rail-to-
Rail Input and Output Op Amp
Input Common Mode Range Extends 44V Above V
–
Independent of V
+
50µA Supply Current per Amplifier, 20mA Output Cur-
rent
Reverse Battery Protected to 18V
No Phase Reversal
No Supply Sequencing Problems
Output Swings to Within 10mV of V
–
and 50mV of V
+
Total Supply Voltage Range: 2V to 44V
Table 1. Typical Performance Summary (Single 3V Supply, T
A
=25°C) Visit www.linear.com for complete data sheet.
PARAMETER
Input Voltage Range
Supply Current
Offset Voltage
Input Bias Current
Gain Bandwidth Product
Slew Rate
CONDITION
Min and Max
Per Amplifier
VALUE
0V to 44V
40µA
220µV
1nA
180KHz
0.06 V/µsec
Device Top Mark Identifier: quick, start, demo
1
QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 591
EVALUATION CARD FOR THE LT1490A IN THE DFN PACKAGE
QUICK START PROCEDURE
Build the evaluation circuit in one of two ways as shown in Figures 1 and 2.
V
CC
GND
V
EE
C1
R2
E
OUT
C3
R1
LA xx
E
IN
GND
C4
R3
GND
R4
C2
Figure 1. External Components Directly on the PCB (0.1•F Bypass Capacitors: AVX 1206C104KAT). Example connections shown may not
be correct for this device.
GROUND WIRE
FOR BYPASS CAPS
DEMONSTRATION
CIRCUIT
DFN
PACKAGE
8-PIN DIP
SOCKET
HEADER: MILL-MAX
3402-0-00-21-00-00-03-0
TEST
BOARD
Figure 2. Convert the Board to an 8-pin DIP Format
2
QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 591
EVALUATION CARD FOR THE LT1490A IN THE DFN PACKAGE
PACKAGE AND CONNECTION DRAWING
R = 0.115
TYP
5
0.58 ±0.05
0.38 ± 0.10
8
3.35 ±0.05
1.65 ±0.05
2.25 ±0.05 (2 SIDES)
PACKAGE
OUTLINE
0.28 ± 0.05
0.50
BSC
2.38 ±0.05
(2 SIDES)
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
PIN 1
TOP MARK
3.00 ±0.10
(4 SIDES)
1.65 ± 0.10
(2 SIDES)
(DD8) DFN 0902
0.200 REF
0.75 ±0.05
4
0.28 ± 0.05
2.38 ±0.10
(2 SIDES)
1
0.50 BSC
0.00 – 0.05
BOTTOM VIEW—EXPOSED PAD
NOTE:
1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION OF (WEED-1)
2. ALL DIMENSIONS ARE IN MILLIMETERS
3. 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
4. EXPOSED PAD SHALL BE SOLDER PLATED
TOP VIEW
OUT A 1
–IN A 2
+IN A 3
V
–
8
A
B
V
+
OUT B
–IN B
+IN B
7
6
5
4
DD PACKAGE
8-LEAD (3mm
×
3mm) PLASTIC DFN
ASSEMBLY TIPS
Following are the recommended procedures for solder-
ing surface mount packages to PC boards.
Reflow Soldering with Solder Paste
•
Use of solder plated boards is recommended.
•
Screen solder paste on board.
•
Mount components on board.
•
Infrared or forced hot air convection reflow is rec-
ommended for best performance. Parameters:
−
Preheat peak temperature 125°C
±
15°C and 2°C
to 4°C per second rise
−
Activation temperature 130°C to 150°C
−
Reflow begins at 183°C (63Sn/37Pb)
−
Time above 183°C for 30 seconds
−
Peak package body temperature 220°C to 245°C
−
Dwell time at peak temperature 10 seconds max
−
Cooling rate 2°C to 4°C per second
−
Clean boards.
•
For Vapor Phase Reflow, recommended parameter
ranges for:
−
Heating rate: 4°C per second max
3
QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 591
EVALUATION CARD FOR THE LT1490A IN THE DFN PACKAGE
−
Preheat temperature: 45°C to 80°C
−
Time above 200°C: 50 seconds to 90 seconds
−
Peak package temperature: 212°C to 219°C
Wave Soldering and Hand Soldering are not recom-
mended.
REWORK GUIDELINES FOR DFN PACKAGES
Each package mounting site should be reworked one at a
time only, to ensure maximum quality and reliability.
Linear Technology has found the following rework pro-
cedure to be effective with DFN packages but by no
means excludes other methods more suited to specific
manufacturing needs.
Reflow Temperature Profile
Each package site to be reworked should be individu-
ally heated. The reflow temperature profile can be es-
tablished using a hot gas tool and a thermocouple
embedded in the solder joints of a sample setup unit
on the PCB.
Preheating and Package Removal
A package rework tool with vacuum pickup similar to
the A.P.E. Flo-Master can be used. A bottom PCB
heater is required to provide preheating of the PCB to
approximately 110°C to 120°C. The rework nozzle
must be centered with respect to the package in order
to direct the hot gas flow over the top of the package
while limiting the temperature of the adjacent compo-
nents to prevent solder reflow.
Site Rework
With a combination on hot gas/vacuum desoldering
tool and solder wick ribbons (if necessary), remove
the package and any remaining solder residues. Use a
minimal amount of flux if it is required to remove sol-
der residue. This will also assist in leaving a smooth,
flat surface for the reattachment of a replacement
unit. The site for the package should be thoroughly
cleaned with isopropyl alcohol (IPA) and dried with
clean dry air (CDA).
Solder Paste Application
Solder paste may be screen printed on to the package
landing site and exposed heat sink pads. Stainless
steel stencils are recommended for solder paste ap-
plication. The printed solder deposits should be 100
percent inspected for uniformity of size and shape.
Some applications may have severe space constraints
preventing screen printing to be accomplished on the
PCB. Therefore, solder paste can be directly applied to
the packages landing site and exposed heatsink pad.
The package is to be picked and placed using a vision
aided system similar to the A.P.E. Sniper SMD 7007
Rework System.
Reflow Process
The replacement package, once it has been placed
onto the reworked PCB landing site, should be re-
flowed on the PCB using a hot gas tool on the top of
the package and a heater on the bottom of the PCB.
The reflow temperature should not exceed 240°C.
Note that liquidus temperature for 63/37 Sn/Pb solder
is 183°C. Make sure to limit adjacent components to
below the solder reflow temperature. The solder paste
manufacturer’s recommended reflow temperature
profile/specifications must be complied with to avoid
damage to the PCB and/or adjacent components. A
100 percent post rework visual inspection for good
joint wetting is recommended.
4
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