Linear Technology DC1444A User manual

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1444A
1-CHANNEL/2-CHANNEL, 12-BIT, SAR ADCS WITH I
2
C INTERFACE
1
DESCRIPTION
LTC2301/LTC2305
Demonstration circuit 1444A features the
LTC2301/LTC2305, low noise, low power, 1-
Channel/2-Channel, 12-Bit, successive
approximation ADCs with an I
2
C compatible
serial interface. The LTC2301/LTC2305 are
available in a 12-pin MSOP package.
DC1444A demonstrates the DC performance
of the LTC2301/LTC2305 ADCs in
conjunction with the DC590B Quick Eval
data collection board. Alternatively, by
connecting the DC1444A into a customer
application the performance of the
LTC2301/LTC2305 can be evaluated directly
in that circuit. DC1444A-A uses
LTC2301CMS.
DC1444A-B uses LTC2305CMS.
Design files for this circuit board are available.
Call the LTC factory.
LTC is a trademark of Linear Technology Corporation
FIGURE 1. DC1444A CONNECTION DIAGRAM

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1444A
1-CHANNEL/2-CHANNEL, 12-BIT, SAR ADCS WITH I
2
C INTERFACE
2
DC590B QUICK START PROCEDURE
Connect DC1444A to a DC590B USB serial
controller using the supplied 14-conductor ribbon
cable. Make sure the VCCIO jumper of the
DC590B is in the 5V position. Connect DC590B
to a host PC with a standard USB A/B cable.
Apply analog input voltage to IN+ and IN- (CH0
and CH1 for LTC2301) on connector JP1. Run the
evaluation software supplied with DC590B or
download it from www.linear.com. The correct
control panel will be loaded automatically. Click
the COLLECT/PAUSE (Figure 2) button to begin
reading the ADC. Pressing COLLECT/PAUSE
again stops data collection. The Help menu
contains information on Data Logging the ADC
results. The Tools menu has the Data Logging
option as well as options for changing the number
of points displayed, the number of points in an
average and whether the data is displayed in LSBs
or Volts. The View menu can be used to access
the LTC2301/LTC2305 product page.
If the Quick Eval program is started without the
demo board attached to DC590B, the Tools menu
can be used to check for updates and automatically
install them. DC1444A requires at least version
K76 of the Quick Eval software.
HARDWARE SET UP
SIGNAL CONNECTIONS
See Figure 1 for locations.
JP1 Connector for IN+/IN- LTC2301 (CH0-
CH1 LTC2305), COM and BIAS/2. Limit input
voltage swings to GND-VDD. For optimum
performance, the input should be bandlimited to
the frequencies of interest.
JP2 DC590 interface connector. Provides power
and I2C interface to DC1444A.
JP3 AD1 I
2
C address line. Set to GND for
operation with supplied software.
JP4 AD0 I
2
C address line. Set to GND for
operation with supplied software.
JP5 BIAS Selects between Refcomp and an
external bias voltage to drive the Bias/2 line.
Bias/2 is designed to set a center point for the
minus input during bipolar operation.
EXT_BIAS External Bias connection. This can
be used to drive the BIAS/2 line through a 2:1
divider. To use this pin put jumper JP5 in the EXT
position and apply desired bias voltage.
5V Five volt supply line for DC1444A. Power is
normally provided to this line by DC590B. Apply
power to this line only if DC590B is not used.
GND Ground line for DC1444A
SDA I
2
C bidirectional data line. Controlled by
DC590B if connected.
SCL I
2
C clock line. Controlled by DC590B if
connected.
VREF Connected to ADC Vref pin through 50
ohm resistor.
REFCOMP Connected to ADC Refcomp pin.
BIAS/2 Bias voltage/2 (Refcomp or Ext)

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1444A
1-CHANNEL/2-CHANNEL, 12-BIT, SAR ADCS WITH I
2
C INTERFACE
3
USING DC1444A WITHOUT DC590
Interface signals SDA and SCL and power are
normally provided to DC1444A by DC590. If you
use this board without DC590, it is the user’s
responsibility to connect a 5V power supply and
ground as well as generating SDA and SCL. These
signals can be provided through the 14-pin ribbon
cable connector. See schematic for pin out. See
LTC2301/LTC2305 Data Sheet for information on
driving SDA and SCL.
Figure 2. DC1444A-A Quick Eval Screenshot

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1444A
1-CHANNEL/2-CHANNEL, 12-BIT, SAR ADCS WITH I
2
C INTERFACE
4