19-4398; Rev 0; 2/09
38V, Low-Noise, MOS-Input,
Low-Power Op Amp
MAX945
General Description
Features
The MAX9945 operational amplifier features an excellent
combination of low operating power and low input volt-
age noise. In addition, MOS inputs enable the MAX9945
to feature low input bias currents and low input current
noise. The device accepts a wide supply voltage range
from 4.75V to 38V and draws a low 400µA quiescent cur-
rent. The MAX9945 is unity-gain stable and is capable of
rail-to-rail output voltage swing.
♦ +4.75V to +38V Single-Supply Voltage Range
♦ ±±.4V to ±ꢀꢁV ꢂual-Supply Voltage Range
♦ Rail-to-Rail Output Voltage Swing
♦ 400µA Low Quiescent Current
♦ 50fA Low Input Bias Current
♦ ꢀfA/√Hz Low Input Current Noise
♦ ꢀ5nV/√Hz Low Noise
The MAX9945 is ideal for portable medical and industri-
al applications that require low noise analog front-ends
for performance applications such as photodiode trans-
impedance and chemical sensor interface circuits.
♦ 3MHz Unity-Gain Bandwidth
The MAX9945 is available in both an 8-pin µMAX® and
a space-saving, 6-pin TDFN package, and is specified
over the automotive operating temperature range
(-40°C to +125°C).
♦ Wide Temperature Range from -40°C to +ꢀ±5°C
♦ Available in Space-Saving, 6-Pin TꢂFN Package
(3mm x 3mm)
Ordering Information
Applications
Medical Pulse Oximetry
PIN-
PACKAGE
TOP
MARK
PART
TEMP RANGE
Photodiode Sensor Interface
Industrial Sensors and Instrumentation
Chemical Sensor Interface
MAX9945ATT+ -40°C to +125°C 6 TDFN-EP*
MAX9945AUA+ -40°C to +125°C 8 µMAX
+Denotes a lead(Pb)-free/RoHS-compliant package.
*EP = Exposed pad.
AUE
—
High-Performance Audio Line Out
Active Filters and Signal Processing
µMAX is a registered trademark of Maxim Integrated Products, Inc.
Typical Operating Circuit
V
CC
PHOTODIODE
IN-
SIGNAL
CONDITIONING/
FILTERS
OUT
ADC
MAX9945
IN+
V
EE
________________________________________________________________ Maxim Integrated Products
ꢀ
For pricing, delivery, and ordering information, please contact Maxim ꢂirect at ꢀ-888-6±ꢁ-464±,
or visit Maxim’s website at www.maxim-ic.com.