1. Overview: LTC2381-16 – 16-Bit ADC

️· Type: Successive Approximation Register (SAR) Analog-to-Digital Converter (ADC)
️· Resolution: 16-bit
️· Differential Input Range: ±2.5V
️· Sampling Rate: Up to 250ksps (kilosamples per second)
️· Supply Voltage (Vdd): 2.375V - 2.625V
️· Reference Voltage (Vref): 2.4V - 2.6V
️· Power Consumption: Low, with auto power-down feature. Approximately 3.25mW at 250ksps.
️· Applications: High-performance data acquisition, precision measurement, instrumentation.

2. Key Features & Benefits

️· High Accuracy: ±2 LSB INL (Integral Non-Linearity) max, no missing codes.
️· Noise Performance: 92dB SNR (Signal-to-Noise Ratio).
️· Fast Throughput: 250ksps with no cycle latency.
️· Extended Acquisition Time: 3.25µs, allows the use of low-power ADC drivers.
️· Flexible Interface: Serial interface for data output.
️· Daisychain Capability: Chain mode functionality (via CHAIN pin) for multiple ADC connections.
️· Power Optimization: Auto power-down for reduced power consumption when inactive.

3. Pin Functions

Pin	Function	Description
CHAIN	Chain Mode Selector/Serial Data Input	Selects Normal (RDL/SDI as enable) or Chain mode (SDI input).
Vdd	Digital Power Supply (Positive)	2.375V - 2.625V. Requires 10µF bypass capacitor to GND.
GND	Ground	Multiple ground pins. Connect to ground plane.
IN+	Positive Differential Analog Input	Differential input, connected to analog signal.
IN-	Negative Differential Analog Input	Differential input, connected to reference/inverted analog signal.
REF	Reference Input	2.4V - 2.6V. Requires 47µF ceramic capacitor to GND.
CNV	Convert Input	Rising edge initiates conversion. Holding CNV high keeps the part powered down.
BUSY	Busy Indicator	High during conversion, low when finished.
RDL/SDI	Bus Enable/Serial Data Input	Function depends on CHAIN pin state.
SCK	Serial Data Clock Input	Clock for serial data output (or input in Chain mode).
SDO	Serial Data Output	Serial data output. Data is 2's complement format.
VddIO	Digital I/O Power Supply (Positive)	1.71V - 5.25V. Requires 0.1µF capacitor to GND. Nominally matches host interface supply.
GND (Exposed Pad)	Ground	For DFN package only. Must be soldered to ground plane.

4. Operating Modes

️· Normal Mode (CHAIN = 0): RDL/SDI pin functions as a bus enable input.
️· Chain Mode (CHAIN = 1): RDL/SDI pin functions as the serial data input pin (SDI) for daisychaining multiple ADCs.

5. Transfer Function

️· Full-Scale Voltage: 2 * Vref (typically 5V with Vref = 2.5V)
️· LSB Size: Vref / 65536 (approximately 76µV with Vref = 2.5V)
️· Data Format: 2's Complement.

Important Notes & Considerations:

️· Bypass Capacitors: Proper bypass capacitors are *crucial* for stable ADC operation.
️· Ground Plane: A solid ground plane is essential for minimizing noise and ensuring signal integrity.
️· Daisychaining: When using Chain mode, careful consideration of timing and data flow is required.
️· Referenced Voltages: Ensure Vdd and Vref are within their specified ranges.