MAX1396 Maxim Integrated Products, MAX1396 Datasheet - Page 8

• Manufacturer Part Number: MAX1396
• Description: (MAX1393 / MAX1396) 1-Channel True-Differential/ 2-Channel Single-Ended
• Manufacturer: Maxim Integrated Products

1.5V to 3.6V, 312.5ksps, 1-Channel True-Differential/
2-Channel Single-Ended, 12-Bit, SAR ADCs
The MAX1393/MAX1396 use an input track and hold
(T/H) circuit along with a SAR to convert an analog input
signal to a serial 12-bit digital output data stream. The
serial interface provides easy interfacing to microproces-
sors and DSPs. Figure 3 shows the simplified functional
diagram for the MAX1393 (1 channel, true differential)
and the MAX1396 (2 channels, single ended).
The equivalent input circuit of Figure 4 shows the
MAX1393/MAX1396 input architecture, which is com-
posed of a T/H, a comparator, and a switched-capacitor
DAC. The T/H enters its tracking mode on the falling
edge of CS (while OE is held low). The positive input
capacitor is connected to AIN+ (MAX1393), or to AIN1 or
AIN2 (MAX1396). The negative input capacitor is con-
nected to AIN- (MAX1393) or GND (MAX1396). The T/H
enters its hold mode on the 3rd falling edge of SCLK
8
MAX1393
_______________________________________________________________________________________
10
—
—
—
—
1
2
3
4
5
6
7
8
9
PIN
True-Differential Analog Input T/H
MAX1396
10
—
—
—
—
1
2
3
4
5
6
7
8
9
Detailed Description
CH1/CH2
UNI/BIP
NAME
DOUT
SCLK
AIN+
AIN2
AIN1
GND
AIN-
V
REF
OE
CS
EP
DD
Positive Supply Voltage. Connect V
with a 0.1µF capacitor as close to the device as possible.
Negative Analog Input
Analog Input Channel 2
Positive Analog Input
Analog Input Channel 1
Ground
External Reference Voltage Input. V
0.1µF capacitor as close to the device as possible.
Input-Mode Select. Drive UNI/BIP high to select unipolar input mode. Pull UNI/BIP low to
select bipolar input mode. In unipolar mode, the output data is in straight binary format. In
bipolar mode, the output data is in two’s complement format.
Channel-Select Input. Pull CH1/CH2 low to select channel 1. Drive CH1/CH2 high to select
channel 2.
Active-Low Output Enable. Pull OE low to enable DOUT. Drive OE high to disable DOUT.
Connect to CS to interface with SPI, QSPI, and MICROWIRE devices or set low to interface
with DSP devices.
Active-Low Chip-Select Input. A falling edge on CS initiates power-up and acquisition.
Serial-Data Output. DOUT changes state on the falling edge of SCLK. DOUT is high
impedance when OE is high.
Serial-Clock Input. SCLK drives the conversion process and clocks data out. Acquisition ends
on the 3rd falling edge after the CS falling edge. The LSB is clocked out on the SCLK 15th
falling edge and the device enters AutoShutdown mode (see Figures 8 , 9, and 10).
Exposed Pad. Not internally connected. Connect the exposed pad to GND or leave floating.
Figure 3. Simplified Functional Diagram
AIN+ (AIN1)*
AIN- (AIN2)*
*INDICATES THE MAX1396
DD
REF
to a 1.5V to 3.6V power supply. Bypass V
REF
= 0.6V to (V
FUNCTION
AND T/H
INPUT
MUX
DD
+ 0.05V). Bypass REF to GND with a
12-BIT SAR
ADC
GND
V
DD
Pin Description
MAX1393
MAX1396
LOGIC AND
CONTROL
REGISTER
TIMING
OUTPUT
SHIFT
DD
to GND
UNI/BIP
(CH1/CH2)*
CS
SCLK
OE
DOUT