MAX1400
+5V, 18-Bit, Low-Power, Multichannel,
Oversampling (Sigma-Delta) ADC
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Pin Description
15 AIN5
Analog Input Channel 5. Used as a differential or pseudo-differential input with AIN6 (see the
Communications Register section).
NAME FUNCTION
1 CLKIN
Clock Input. A crystal can be connected across CLKIN and CLKOUT. Alternatively, drive CLKIN with a
CMOS-compatible clock at a nominal frequency of 2.4576MHz or 1.024MHz, and leave CLKOUT uncon-
nected. Frequencies of 4.9152MHz and 2.048MHz can be used if the X2CLK control bit is set to 1.
PIN
2 CLKOUT
Clock Output. When deriving the master clock from a crystal, connect the crystal between CLKIN and
CLKOUT. In this mode, the on-chip clock signal is not available at CLKOUT. Leave CLKOUT unconnected
when CLKIN is driven with an external clock.
3
CS
Chip-Select Input. Active-low logic input used to enable the digital interface. With CS hard-wired low, the
MAX1400 operates in its 3-wire interface mode with SCLK, DIN and DOUT used to interface to the device.
CS is used either to select the device in systems with more than one device on the serial bus, or as a
frame-synchronization signal for the MAX1400 when a continuous SCLK is used.
4
RESET
Active Low Reset Input. Drive low to reset the control logic, interface logic, digital filter and analog modu-
lator to power-on status. RESET must be high and CLKIN must be toggling in order to exit reset.
5 MUXOUT+
Positive Analog Mux Output. The positive differential output signal from the part’s internal input multiplex-
er. Use this signal in conjunction with MUXOUT- and a high-quality external amplifier for additional signal
processing before conversion. Return the processed output through ADCIN+ and ADCIN-. Connect
MUXOUT+ directly to ADCIN+ if external processing is not required.
6 MUXOUT-
Negative Analog Mux Output. The negative differential output signal from the part’s internal input multi-
plexer. Use this signal in conjunction with MUXOUT+ and a high-quality external amplifier for additional
signal processing before conversion. Return the processed output through ADCIN+ and ADCIN-.
Connect MUXOUT- directly to ADCIN- if external processing is not required.
7 ADCIN+
Positive Analog Input. A direct input to the positive buffer and the positive differential input terminal of the
ADC, bypassing the input mux. This signal forms a differential input pair with ADCIN-. Connect ADCIN+ to
MUXOUT+ when direct access is not required.
8 ADCIN-
Negative Analog Input. A direct input to the negative buffer and the negative differential input terminal of
the ADC - bypassing the input mux. This signal forms a differential input pair with ADCIN+. Connect
ADCIN- to MUXOUT- when direct access is not required.
9 AGND Analog Ground. Reference point for the analog circuitry. AGND connects to the IC substrate.
10 V+ Analog Positive Supply Voltage (+4.75V to +5.25V)
11 AIN1
Analog Input Channel 1. Can be used as a pseudo-differential input with AIN6 as common, or as the posi-
tive input of the AIN1/AIN2 differential analog input pair (see the Communications Register section).
12 AIN2
Analog Input Channel 2. Can be used as a pseudo-differential input with AIN6 as common, or as the neg-
ative input of the AIN1/AIN2 differential analog input pair (see the Communications Register section).
13 AIN3
Analog Input Channel 3. Can be used as a pseudo-differential input with AIN6 as common, or as the posi-
tive input of the AIN3/AIN4 differential analog input pair (see the Communications Register section).
14 AIN4
Analog Input Channel 4. Can be used as a pseudo-differential input with AIN6 as common, or as the neg-
ative input of the AIN3/AIN4 differential analog input pair (see the Communications Register section).
16 AIN6
Analog Input 6. Can be used as a common point for AIN1 through AIN5 in pseudo-differential mode, or as
the negative input of the AIN5/AIN6 differential analog input pair (see the Communications Register section).
