Datasheet

11Maxim Integrated
3V/5V Low-Power, Low-Noise, CMOS,
Rail-to-Rail I/O Op Amps
MAX9636/MAX9637/MAX9638
For best performance, follow standard high-impedance
layout techniques, which include the following:
U Using shielding techniques to guard against parasitic
leakage paths. For example, put a trace connected to
the noninverting input around the inverting input.
U Minimizing the amount of stray capacitance connect-
ed to op amp’s inputs to improve stability. To achieve
this, minimize trace lengths and resistor leads by
placing external components as close as possible to
the package.
U Use separate analog and digital power supplies.
Applications Information
Shutdown Operation
The MAX9636/MAX9638 feature an active-low shutdown
mode that sends the inputs and output into high imped-
ance and substantially lowers the quiescent current.
Active-Low Input
The shutdown active-low (V
IL
) and high (V
IH
) threshold
voltages are designed for ease of integration with digital
controls, such as microcontroller outputs. These thresh-
olds are independent of supply, eliminating the need for
external pulldown circuitry.
Output During Shutdown
The MAX9636/MAX9638 output is in a high-impedance
state while SHDN is low. The device structure limits the out-
put leakage current in this state to 0.01µA when the out-
put is between 0V to V
DD
.
ADC Driver
The MAX9636/MAX9637/MAX9638 are low-power ampli-
fiers ideal for driving high to medium-resolution ADCs.
Figure 3 shows how the MAX9636 is connected to a pho-
todiode, with the amplifier output connected to additional
signal conditioning/filtering, or directly to the ADC. The
MAX1286–MAX1289 family of low-power, 12-bit ADCs are
ideal for connecting to the MAX9636/MAX9637/MAX9638.
The MAX1286–MAX1289 ADCs offer sample rates up
to 150ksps, with 3V and 5V supplies, as well as 1- and
2-channel options. These ADCs dissipate just 15µA when
sampling at 10ksps and 0.2µA in shutdown. Offered in
tiny 8-pin SOT23 and 3mm x 3mm TDFN packages, the
MAX1286–MAX1289 ADCs are an ideal fit to pair with
the MAX9636/MAX9637/MAX9638 amplifiers in portable
applications.
Similarly, the MAX1086–MAX1089 is a family of 10-bit
pin-compatible low-power ADCs with the same 3V/5V,
1- and 2-channel options. Table 1 details the amplifier and
ADC pairings for single- and dual-channel applications.
Chip Information
PROCESS: BiCMOS
Table 1. Recommended Amplifiers/ADCs
CHANNELS AMPLIFIER
ADC
3V, 10 BIT 3V, 12 BIT 5V, 10 BIT 5V, 12 BIT
1 MAX9636 MAX1089 MAX1289 MAX1088 MAX1288
2 MAX9637 MAX1087 MAX1287 MAX1086 MAX1286
2 MAX9638 MAX1087 MAX1287 MAX1086 MAX1286