MAX4291 Maxim, MAX4291 Datasheet - Page 13

• Manufacturer Part Number: MAX4291
• Description: The MAX4291/MAX4292/MAX4294 family of micropower operational amplifiers operates from a 1
• Manufacturer: Maxim

For a 1V output and a current load of 50mA, the choice
of resistors can be R1 = 2 , R2 = 100k , and R3 =
1M .
Design the layout for the IC to be as compact as possi-
ble to minimize parasitics. The UCSP uses a bump
pitch of 0.5mm (19.7mil) and bump diameter of 0.3
(~12mil). Therefore, lay out the solder-pad spacing on
0.5mm (19.7mil) centers, using a pad size of 0.25mm
(~10mil) and a solder mask opening of 0.33mm (13mil).
Round or square pads are permissible. Connect multi-
ple vias from the ground plane as close to the ground
pins as possible.
Install capacitors as close as possible to the IC supply
voltage pin. Place the ground end of these capacitors
near the IC GND pins to provide a low-impedance
return path for the signal current.
Alignment keys on the PC board, around the area
where the chip is located, will be helpful in the proto-
type assembly process. It is better to align the chip on
the board before any other components are placed,
and then place the board on a hot plate or hot surface
until the solder starts melting. Remove the board from
the hot plate without disturbing the position of the chip
and let it cool down to room temperature before pro-
cessing the board further.
The UCSP represents a unique packaging form factor
that may not perform as well as a packaged product
through traditional mechanical reliability tests. UCSP
reliability is integrally linked to the user’s assembly
methods, circuit board material, and usage environ-
ment. The user should closely review these areas when
considering use of a UCSP.
Performance through operating-life test and moisture
resistance remains uncompromised. The wafer-fabrica-
tion process primarily determines the performance.
Mechanical stress performance is a greater considera-
tion for UCSPs. UCSPs are attached through direct sol-
der contact to the user’s PC board, foregoing the
inherent stress relief of a packaged product lead frame.
Solder-joint contact integrity must be considered.
Comprehensive reliability tests have been performed
and are available upon request. In conclusion, the
UCSP performs reliably through environmental stresses.
______________________________________________________________________________________
Prototype Chip Installation
UCSP Information
UCSP Reliability
Layout Issues
Ultra-Small, 1.8V, µPower,
Rail-to-Rail I/O Op Amps
Figure 11. Current Monitor for a 2-Cell Battery Stack
V
OUT
R3
R2
Q1
I
LOAD
AAA
AAA
Marking Information
R1
ORIENTATION
PRODUCT ID CODE
LOT CODE
MAX4291
V
V
CC
EE
13