8-Bit CODECs
MAX1102/MAX1103/MAX1104
Pin Description
PIN
1
2
3
4
5
6
7
8
NAME
V
DD
GND
AIN
OUT
CS
SCLK
DOUT
DIN
Voltage Supply
Ground
ADC Analog Input
DAC Analog Voltage Output
Chip Select Input. Device ignores all logic signals when
CS
is high.
Serial Clock Input. Data in is latched on the rising edge, data out transitions on the falling edge.
ADC Digital Output. Output is high impedance when
CS
is high.
DAC Digital Input. Input ignores all signals when
CS
is high.
FUNCTION
Detailed Description
The MAX1102/MAX1103/MAX1104 are 8-bit CODECs in
a compact 8-pin package. These devices consist of an
8-bit ADC, an 8-bit DAC, track/hold (T/H), DAC output
buffer amplifier, internal voltage reference, input multi-
plexer (mux) and a 6MHz SPI, QSPI and MICROWIRE
compatible 4-wire serial interface. A single 8-bit word
configures the MAX1102/MAX1103/MAX1104, provid-
ing a simple interface to a microcontroller (µC).
shows the detailed functional diagram of the ADC
block.
ADC Operation
The input architecture of the ADC is illustrated in Figure
2, the equivalent input circuit, and is composed of the
T/H, input mux (MAX1102/MAX1103), input comparator,
switched capacitor DAC, and the auto-zero rail. The
switched capacitor DAC is independent of the R-2R
ladder DAC and does not provide the converted analog
output on OUT.
The T/H is in hold mode while a conversion is taking
place. Once the conversion is completed, the T/H
enters acquisition mode, and tracks the input signal
until the start of the next conversion. In single conver-
sion mode, conversion starts at the falling clock edge
corresponding to the last bit of the control word. In con-
tinuous conversion mode, the first conversion following
the control word starts on the falling clock edge of the
Analog-to-Digital Converter
The MAX1102/MAX1103/MAX1104 ADC section uses a
successive-approximation (SAR) conversion technique
and input T/H circuitry to convert an analog signal to an
8-bit digital output. No external hold capacitors are
required. The MAX1102/MAX1103 have an input multi-
plexer that directs either AIN or V
DD
/2 to the input of
the T/H, allowing these devices to either convert the
analog input, or monitor the power supply. Figure 1
CS
SCLK
DIN
CONTROL
LOGIC/2
INTERNAL
OSCILLATOR
MAX1102
MAX1103
AIN
V
DD
/2
ANALOG
INPUT
MUX
T/H
SUCCESSIVE
APPROXIMATION
REGISTER
CHARGE
REDISTRIBUTION
DAC
ANALOG
OUTPUT
INPUT
SHIFT
MUX
REGISTER
DOUT
INTERNAL
OSCILLATOR
Figure 1. ADC Detailed Functional Diagram
8
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