MAX11359AETL+ Maxim Integrated Products, MAX11359AETL+ Datasheet - Page 60

• Manufacturer Part Number: MAX11359AETL+
• Description: IC DAS SYSTEM 16BIT 40-TQFN
• Manufacturer: Maxim Integrated Products
• Type: Data Acquisition System (DAS)r

Specifications of MAX11359AETL+

• Resolution (bits): 16 b
• Sampling Rate (per Second): 477
• Data Interface: MICROWIRE™, QSPI™, Serial, SPI™
• Voltage Supply Source: Analog and Digital
• Voltage - Supply: 1.8 V ~ 3.6 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 40-TQFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

16-Bit Data-Acquisition System with ADC, DAC,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
A CMOS signal may be used to drive 32KIN if it is
divided down. Figure 25 is an example circuit, which
works well.
The mux inputs can range between AGND to AV
However, when the internal temperature sensor is
enabled, AIN1 and AIN2 cannot exceed 0.7V. This
necessitates additional circuitry to divide down the
input signal. See Figure 26 for an example circuit that
divides down backlight V
AIN1 pin.
Figure 27 illustrates the MAX11359A in a complete opti-
cal reflectometry application with two transmitting LEDs
and one receiving photodiode. The LEDs transmit light
at a specific wavelength onto the sample strip, and the
photodiode receives the reflections from the strip. Set
the DAC to provide appropriate bias currents for the
LEDs. Always keep the photodiodes reverse-biased or
zero-biased. SPDT1 and SPDT2 switch between the
two LEDs.
The MAX11359A family interfaces with electrochemical
sensors. The 10-bit DAC with the force-sense buffers
have the flexibility to connect to many different types of
sensors. An external precision resistor completes the
transimpedance amplifier configuration to convert the
current generated by the sensor to a voltage measure-
ment using the ADC. The induced error from this source
is negligible due to FBA’s extremely low input bias cur-
rent. Internally, the ADC can differentially measure
Figure 25. Clocking with a CMOS Signal
60
______________________________________________________________________________________
Optical Reflectometry Application with
CMOS CLOCK
(0 TO DV
Electrochemical Sensor Operation
DD
)
Dual LED and Single Photodiode
Clocking with a CMOS Signal
100kΩ
100kΩ
DD
to work properly with the
Input Multiplexer
32KIN
MAX11359A
DD
.
directly across the external transimpedance resistor,
RF, eliminating any errors due to voltages drifting over
time, temperature, or supply voltage.
Use two diode-connected 2N3904 transistors for exter-
nal temperature sensing in Figure 28. Select AIN1 and
AIN2 through the positive and negative mux, respec-
tively. For internal temperature sensor measurements,
set MUXP<3:0> to 0111, and set MUXN<3:0> to 0000.
The analog input signals feed through a PGA to the
ADC for conversion.
Use two op amps and two SPDT switches to implement
a programmable-gain instrumentation amplifier as
shown in Figure 29.
The MAX11359A integrated PWM is available for LCD bias
control, sensor-bias voltage trimming, buzzer drive, and
duty-cycled sleep-mode power-control schemes. Figure
30 shows the MAX11359A performing LCD bias control.
A sensor-bias voltage trimming application is shown in
Figure 31. Figures 33 and 34 show the PWM circuitry
being used in a single-ended and differential piezo-
electric buzzer-driving application.
Internal to the MAX11359A, the ADC is 24 bits and is
always in bipolar mode. The OFFSET CAL and GAIN
CAL data are also 24 bits. The conversion to unipolar
and the gain are performed digitally. The default values
for the OFFSET CAL and GAIN CAL registers in the
MAX11359A are 00 0000h and 80 0000h, respectively.
Figure 26. Input Multiplexer
V
BATT1
Programmable-Gain Instrumentation
MAX11359A
V
REF
Temperature Measurement with
x2
= 1.25V
µP
UPIO1
V
AIN1
BATT2
GPIOn
BATTVCHECK
Two Remote Sensors
< 0.6125V
PWM Applications
ADC Calibration
NOTE:
GPIOn IS LOW = LED ON,
HIGH-Z = LED OFF
BACKLIGHT
V
DD
Amplifier