MAX1366ECM Maxim Integrated, MAX1366ECM Datasheet - Page 12

• Manufacturer Part Number: MAX1366ECM
• Description: LED Display Drivers
• Manufacturer: Maxim Integrated

The MAX1366/MAX1368 low-power, highly integrated
ADCs with LED drivers convert a ±2V differential input
voltage (one count is equal to 100µV for the MAX1366
and 1mV for the MAX1368) with a sigma-delta ADC and
output the result to an LED display. An additional
±200mV input range (one count is equal to 10µV for the
MAX1366 and 100µV for the MAX1368) is available to
measure small signals with finer resolution.
In addition to displaying the results on an LED display,
these devices feature a DAC and V-to-I converter for
4–20mA (or 0 to 16mA) current output that proportional-
ly follows the ADC input. The MAX1366/MAX1368 use
an external depletion-mode nMOS transistor to regulate
7V to 30V for the V/I converter. Use the 4–20mA (or 0 to
16mA) output to drive a remote display, data logger,
PLC input, or other 4–20mA devices in a current loop.
The MAX1366/MAX1368 interface with a µC using an
SPI-/QSPI-/MICROWIRE-compatible serial interface.
Microcontroller-Interface, 4.5-/3.5-Digit Panel
Meters with 4–20mA Output
12
______________________________________________________________________________________
NEGV
REF+
AIN+
REF-
AIN-
AV
DD
(MAX1368)
MAX1366
CHARGE
BUFFER
+2.5V
INPUT
PUMP
-2.5V
DV
Detailed Description
DD
-2.5V
GND
CLK SCLK DIN DOUT CS
REFERENCE
SERIAL I/O AND CONTROL
BANDGAP
2.048V
ADC
CS_DAC
DISPLAY REGISTER
ADC REGISTER
DAC REGISTER
CS_DAC
DIN
REFSELE
DAC REF
BUFFER
SCLK
REF_DAC
For added flexibility, the MAX1366/MAX1368 allow
direct access to the ADC register, LED display register,
and DAC output register using the SPI interface.
The MAX1366/MAX1368 include a 2.048V reference,
internal charge pump, and a high-accuracy on-chip
oscillator. The devices feature on-chip buffers for the dif-
ferential input signal and external-reference inputs,
allowing direct interface with high-impedance signal
sources. In addition, they use continuous internal offset
calibration and offer > 100dB of 50Hz and 60Hz line-
noise rejection. Other features include data hold and
peak detection and overrange/underrange detection.
The MAX1366/MAX1368 provide internal protection
diodes that limit the analog input range on AIN+, AIN-,
REF+, and REF- from NEGV to (AV
analog input exceeds this range, limit the input current
to 10mA.
EOC
OUTPUT
DAC
REG_AMP
DACDATA_SEL
5V REGULATOR
CMP
SET
REG_FORCE
DRIVER
CONVERTER
LED
LEDV
V/I
Functional Diagram
REG_VDD
Analog Input Protection
GENERATOR
AMPLIFIER
CURRENT
SUMMER
OFFSET
AND
DD
+ 0.3V). If the
SEGA
SEGG
DIG0(1)
DIG4(4)
LED_EN
LEDG
DAC_VDD
DACVOUT
CONV_IN
4-20OUT
EN_I
EN_BPM