MAX9633ATA+T Maxim Integrated Products, MAX9633ATA+T Datasheet - Page 9

• Manufacturer Part Number: MAX9633ATA+T
• Description: Op Amps OPERATIONAL AMP Low-Noise Wide-Band
• Manufacturer: Maxim Integrated Products

Specifications of MAX9633ATA+T

• Number Of Channels: 2
• Common Mode Rejection Ratio (min): 105 dB
• Input Voltage Range (max): 36 V
• Input Voltage Range (min): 4.5 V
• Input Offset Voltage: 70 uV
• Input Bias Current (max): 22 uA
• Supply Current: 3.5 mA
• Maximum Power Dissipation: 1904.8 mW
• Maximum Operating Temperature: + 125 C
• Minimum Operating Temperature: - 40 C
• Mounting Style: SMD/SMT
• Slew Rate: 18 V/us
• Package / Case: TDFN-8
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

1)
The MAX9633 is designed in a new 36V, high-speed
complementary BiCMOS process that is optimized for
excellent AC dynamic performance combined with high-
voltage operation.
The exceptionally fast settling time, low noise, low distor-
tion, high bandwidth, and low input offset voltage make
the IC an excellent solution to drive (up to 18-bit)high-
resolution and fast SAR ADCs.
The MAX9633 is unity gain stable and operates either
with a single supply voltage up to 36V or with dual sup-
plies up to Q18V.
High-resolution SAR ADCs typically switch an input
capacitor in the order of tens of pF during the track and
hold phases. Such capacitor switching can cause a
voltage glitch at the input of the ADC that behaves as a
load-transient condition for the driving amplifier. In many
applications, this glitch is avoided by placing an external
capacitor at the ADC input that is in the order of 20 to 50
times the ADC input capacitor. If the ADC input capaci-
tor ranges from 15pF to 30pF, then the external capacitor
is anything between 300pF to 1.5nF, depending on the
application. An isolation resistor can be placed in series
between the amplifier’s output and the external capaci-
tor, as shown in the Typical Application Circuit.
During the load-transient condition described, the driv-
ing amplifier must be able to settle to 0.5 x LSB within
the ADC acquisition time (t
approximation, the number of time constants required to
settle to 0.5 x LSB is a logarithm function of the number
N of bits:
The external RC time constant must be such that:
2)
As an example, consider a 16-bit SAR ADC with 500ns
acquisition time and 20pF input capacitor.
From 1):
Assuming a factor of 50 for the external capacitor:
Finally, formula 2) gives: R
The IC is optimized for very fast load-transient recovery
with big capacitive loads and small isolation resistors.
Driving High-Resolution SAR ADCs
Applications Information
k x R
k
Detailed Description
=
L
C = 1nF
ln 2
k = 12
x C < t
(
L
ACQ
N 1
P 40I
+
). Assuming a first order
)
ACQ
Dual 36V Op Amp for 18-Bit
This makes it ideal to drive high-resolution and fast SAR
ADCs.
The MAX9633’s wide supply range and fast settling
make it ideal for driving high-resolution SAR ADCs, such
as the MAX1320. The MAX1320 is a 14-bit, 8-chan-
nel, simultaneous-sampling ADC that measures analog
inputs up to Q5V. Sampling up to 250ksps per channel
for eight channels, the MAX1320 achieves 77dB SNR,
90dBc SFDR, and -86dB THD. The MAX1320’s fast
sample rate and typical input resistance of 8.6kI often
make it necessary to have a low-noise op amp, such as
the MAX9633, driving its inputs. The MAX9633 is also
a good fit for an anti-aliasing active filter prior to the
MAX1320 as shown in the Typical Application Circuit.
The MAX1320 is part of a family of simultaneous sampling
ADCs (MAX1316–MAX1326). Other options include ADCs
that measure 0V to 5V inputs, or Q10V inputs, and two 4
or 8 simultaneous input channels. The MAX1320’s high
speed and resolution make it a fit for multiphase motor
control and power-grid monitoring.
The MAX9633 is also well-suited to drive the 16-bit
MAX11046 8-channel, simultaneous-sampling, SAR
ADC. The MAX11046 is rated for up to 250ksps. An input
driver is typically not necessary at sampling rates below
100ksps. For applications that require > 100ksps sample
rates, the MAX9633 offers small size, high bandwidth,
and ultra-low -100dB THD at 100kHz.
The MAX9633 is designed for applications that require
very low voltage noise, making it ideal for low source
impedance. When driving 16-bit SAR ADCs with a Q5V
full-scale input, such as the MAX11046, the MAX9633
very low input voltage noise density specification guaran-
tees 16-bit resolution up to 10MHz of signal bandwidth.
The MAX9633 is also designed for ultra-low distor-
tion performance. THD specifications in the Electrical
Characteristics and Typical Operating Characteristics
is calculated up to the 5th harmonic. Even when driving
high voltage swing up to 10V
excellent low distortion operation up and beyond 100kHz
of bandwidth.
Besides driving high-resolution and high-bandwidth SAR
ADCs, applications that benefit for low-noise and low-
distortion applications can be found in industrial power-
grid and smart-grid, industrial motor-control, medical
imaging, automated test equipment, instrumentation,
and professional audio equipment.
SAR ADC Front-End
Low Noise and Low Distortion
Recommended SAR ADCs
P-P
, the MAX9633 maintains
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