LTC2415-1CGN Linear Technology, LTC2415-1CGN Datasheet - Page 13

• Manufacturer Part Number: LTC2415-1CGN
• Description: IC ADC 24BIT DIFFINPUT/REF16SSOP
• Manufacturer: Linear Technology

Specifications of LTC2415-1CGN

• Number Of Bits: 24
• Sampling Rate (per Second): 13.75
• Data Interface: MICROWIRE™, Serial, SPI™
• Number Of Converters: 2
• Power Dissipation (max): 1mW
• Voltage Supply Source: Single Supply
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 16-SSOP (0.150", 3.90mm Width)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

APPLICATIO S I FOR ATIO
The LTC2415/LTC2415-1 perform a full-scale calibration
every conversion cycle. This calibration is transparent to
the user and has no effect on the cyclic operation de-
scribed above. The advantage of continuous calibration is
extreme stability of full-scale readings with respect to time,
supply voltage change and temperature drift.
Unlike the LTC2410 and LTC2413, the LTC2415 and
LTC2415-1 do not perform an offset calibration every
conversion cycle. This enables the LTC2415/LTC2415-1
to double their output rate while maintaining line frequency
rejection. The initial offset of the LTC2415/LTC2415-1 is
within 2mV independent of V
LTC2415-1 new modulator architecture, the temperature
drift of the offset is less then 0.01ppm/ C. More informa-
tion on the LTC2415/LTC2415-1 offset is described in the
Offset Accuracy and Drift section of this data sheet.
Power-Up Sequence
The LTC2415/LTC2415-1 automatically enter an internal
reset state when the power supply voltage V
below approximately 2.2V. This feature guarantees the
integrity of the conversion result and of the serial interface
mode selection. (See the 2-wire I/O sections in the Serial
Interface Timing Modes section.)
When the V
the converter creates an internal power-on-reset (POR)
signal with a duration of approximately 0.5ms. The POR
signal clears all internal registers. Following the POR
signal, the LTC2415/LTC2415-1 start a normal conversion
cycle and follow the succession of states described above.
The first conversion result following POR is accurate
within the specifications of the device if the power supply
voltage is restored within the operating range (2.7V to
5.5V) before the end of the POR time interval.
Reference Voltage Range
These converters accept a truly differential external refer-
ence voltage. The absolute/common mode voltage speci-
fication for the REF
from GND to V
REF
+
pin must always be more positive than the REF
CC
voltage rises above this critical threshold,
CC
. For correct converter operation, the
+
U
and REF
U
–
REF
pins covers the entire range
. Based on the LTC2415/
W
U
CC
drops
–
pin.
The LTC2415/LTC2415-1 can accept a differential refer-
ence voltage from 0.1V to V
is determined by the thermal noise of the front-end cir-
cuits, and as such, its value in nanovolts is nearly constant
with reference voltage. A decrease in reference voltage will
not significantly improve the converter’s effective resolu-
tion. On the other hand, a reduced reference voltage will
improve the converter’s overall INL performance. A re-
duced reference voltage will also improve the converter
performance when operated with an external conversion
clock (external F
data rates (see the Output Data Rate section).
Input Voltage Range
The analog input is truly differential with an absolute/
common mode range for the IN
extending from GND – 0.3V to V
these limits, the ESD protection devices begin to turn on
and the errors due to input leakage current increase
rapidly. Within these limits, the LTC2415/LTC2415-1 con-
vert the bipolar differential input signal, V
from – FS = – 0.5 • V
REF
the overrange or the underrange condition using distinct
output codes.
Input signals applied to IN
300mV below ground and above V
fault current, resistors of up to 5k may be added in series
with the IN
mance of the device. In the physical layout, it is important
to maintain the parasitic capacitance of the connection
between these series resistors and the corresponding pins
as low as possible; therefore, the resistors should be
located as close as practical to the pins. The effect of the
series resistance on the converter accuracy can be evalu-
ated from the curves presented in the Input Current/
Reference Current sections. In addition, series resistors
will introduce a temperature dependent offset error due to
the input leakage current. A 1nA input leakage current will
develop a 1ppm offset error on a 5k resistor if V
This error has a very strong temperature dependency.
+
– REF
–
+
. Outside this range, the converters indicate
and IN
LTC2415/LTC2415-1
O
signal) at substantially higher output
REF
–
pins without affecting the perfor-
to +FS = 0.5 • V
+
CC
and IN
. The converter output noise
CC
+
–
CC
. In order to limit any
and IN
pins may extend by
REF
+ 0.3V. Outside
IN
where V
–
= IN
input pins
sn2415 24151fs
REF
+
13
– IN
= 5V.
REF
–
=
,