Analog Devices Inc. LTC1858CG#TRPBF

Overview

LTC1858CG#TRPBF from Analog Devices (formerly Linear Technology) is a 14-bit, 8-channel, 100ksps software-programmable analog-to-digital converter with ±25V fault-protected inputs, single 5V supply operation, and SPI/MICROWIRE-compatible serial interface. It supports selectable unipolar (0V–5V, 0V–10V) or bipolar (±5V, ±10V) input spans and delivers ±1.5LSB integral nonlinearity, 83dB SNR, and 40mW typical power dissipation - deployed in industrial process control and multiplexed data acquisition systems.

For engineers reviewing the LTC1858CG#TRPBF datasheet, LTC1858CG#TRPBF pinout, LTC1858CG#TRPBF application, or LTC1858CG#TRPBF equivalent, key selection criteria include its SoftSpan™ programmable input range per channel, ±25V overvoltage protection on all MUX inputs, internal 2.5V reference with 4.096V buffered output, 28-pin SSOP package, and guaranteed 100ksps sampling rate with 5µs max conversion time.

Technical Context

The LTC1858CG#TRPBF implements a successive approximation register (SAR) architecture with integrated sample-and-hold, precision internal reference, and trim-compensated resistor network for software-configurable input scaling. Its SoftSpan™ circuitry applies channel-specific attenuation and offset before the 8-channel analog multiplexer, eliminating errors from MUX on-resistance and enabling independent span selection per channel.

It features dual shutdown modes (Nap and Sleep), fault isolation that prevents overvoltage on unselected channels from affecting conversion accuracy, and synchronous serial I/O with active-low RD, SCK, SDI, and SDO pins. The internal clock is factory-trimmed to ensure ≤5µs conversion time across temperature and supply voltage variations.

Key Specifications

Pinout & Package

Package: 28-pin Plastic SSOP (G package), 0°C to 70°C operating temperature range, lead-free finish, tape-and-reel packaging.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar multichannel SAR ADC applications.

Compared with AD7606BSTZ and ADS8688IPWR, the LTC1858CG#TRPBF uniquely combines ±25V fault tolerance, per-channel software-selectable spans, and 40mW ultra-low active power in a single 5V-supply device - making it optimal for space-constrained, mixed-range industrial DAQ where robustness and configurability outweigh raw resolution or interface speed.

Availability

LTC1858CG#TRPBF is available at Aetrix Electronics and suitable for industrial process control, multiplexed data acquisition systems, and PC-based high-speed DAQ requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for LTC1858CG#TRPBF includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Analog Devices, Inc. (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors.

The LTC1858CG#TRPBF belongs to Linear's SoftSpan™ precision ADC family, designed specifically for industrial and instrumentation applications demanding flexible input configuration, high fault tolerance, and minimal external component count.

FAQ

What is the maximum sampling rate supported by the LTC1858CG#TRPBF?

The LTC1858CG#TRPBF guarantees a maximum sampling rate of 100ksps when converting through any of the eight analog input channels (CH0–CH7). This is achieved with a maximum conversion time of 5µs and an acquisition time of 4µs. When using only the dedicated ADC+ and ADC– pins (bypassing the multiplexer), the device supports up to 166ksps - though this mode sacrifices multichannel capability. The internal clock is factory-trimmed to ensure this performance across temperature and supply voltage variations.

Does the LTC1858CG#TRPBF require an external reference voltage?

No, the LTC1858CG#TRPBF does not require an external reference voltage. It integrates a factory-trimmed 2.5V bandgap reference (available at VREF pin) and a precision 4.096V buffered output (at REFCOMP pin) for driving the internal DAC. These references support full-scale ranges of 0V–5V, 0V–10V, ±5V, and ±10V. However, the VREF pin can be overdriven with an external reference if higher absolute accuracy is required - the LTC1858CG#TRPBF will seamlessly use the external source instead of the internal one.

How does the SoftSpan™ feature work on the LTC1858CG#TRPBF?

The SoftSpan™ feature on the LTC1858CG#TRPBF uses on-chip resistor networks and switches to apply channel-specific attenuation and offset before the analog multiplexer. An 8-bit command word sent via SDI configures both the channel address and its input span (0V–5V, 0V–10V, ±5V, or ±10V) simultaneously. Because scaling occurs prior to multiplexing, errors from MUX on-resistance are eliminated, and each channel retains independent range selection - enabling mixed-signal acquisition (e.g., ±10V thermocouple + 0V–5V potentiometer) without external recalibration or hardware changes.

What are the power consumption modes of the LTC1858CG#TRPBF?

The LTC1858CG#TRPBF offers two user-selectable low-power modes: Nap mode draws 8mA (40mW at 5V), and Sleep mode draws just 5.5µA (27.5µW). Power state is controlled via bits in the 8-bit SDI command word. In Nap mode, the reference and clock remain active for fast wake-up; in Sleep mode, most internal circuitry is disabled. Both modes retain register settings and allow immediate resumption of conversion upon exit - making the LTC1858CG#TRPBF ideal for duty-cycled data loggers and energy-sensitive industrial sensors.

Can the LTC1858CG#TRPBF handle overvoltage conditions on unused channels?

Yes, the LTC1858CG#TRPBF provides ±25V overvoltage protection on all analog input pins (CH0–CH7 and COM), and critically, a fault condition on any unselected channel will not affect the conversion result of the selected channel. This is achieved through internal fault-isolation circuitry that prevents leakage or latch-up from propagating across the multiplexer. As confirmed in the datasheet, this protection operates independently per channel and remains effective even during continuous overvoltage exposure - a key reliability feature for industrial fieldbus and PLC applications where sensor wiring faults are common.