Texas Instruments TLC1549CDG4

Overview

TLC1549CDG4 from Texas Instruments is a 10-bit switched-capacitor successive-approximation analog-to-digital converter with built-in sample-and-hold, serial three-wire interface (CS, I/O CLOCK, DATA OUT), ±1 LSB total unadjusted error, and on-chip system clock. It operates from 0°C to 70°C and supports ratiometric conversion via differential reference inputs (REF+, REF–), making it suitable for embedded sensor signal acquisition in industrial control and data logging systems.

For engineers reviewing the TLC1549CDG4 datasheet, TLC1549CDG4 pinout, TLC1549CDG4 application, or TLC1549CDG4 equivalent, key selection considerations include its 21 µs conversion time, 2.1 MHz max I/O CLOCK frequency, CMOS-compatible 3-state serial output, 1 kΩ max source impedance requirement at ANALOG IN, and compatibility with TLC549/TLV1549 terminal layouts.

Technical Context

The TLC1549CDG4 implements a charge-redistribution successive-approximation architecture using binary-weighted capacitors, where sampling begins on the third falling edge of I/O CLOCK and holds on the tenth. Its internal system clock eliminates external timing components, and the differential high-impedance reference inputs enable precise ratiometric scaling independent of supply noise.

It supports six serial interface modes-three fast (≤21 µs post-tenth-clock) and three slow-determined by CS state (active low continuously or toggled) and I/O CLOCK count (10, 11–16). The 3-state DATA OUT transitions from high-impedance to active on CS low, with MSB appearing either on CS falling edge (mode 1/3/5) or within 21 µs after tenth clock (mode 2/4).

Key Specifications

Pinout & Package

Package: SOIC-8 (D package, G4 suffix denotes green/RoHS-compliant variant). Pinout applies to D, JG, and P packages per datasheet Figure 1.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 10-bit serial ADC applications.

Compared with TLV1549CD and ADS7822U, the TLC1549CDG4 provides superior DC accuracy (±1 LSB) and true differential reference capability at the cost of higher supply current and fixed 5-V operation-making it optimal for precision industrial sensing where ratiometric stability is critical.

Availability

TLC1549CDG4 is available at Aetrix Electronics and suitable for industrial control systems, embedded data loggers, test equipment front-ends, and legacy microcontroller upgrades requiring stable component supply and long-term obsolescence mitigation.

Supply support for TLC1549CDG4 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

Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and connectivity technologies, with decades of heritage in precision data converters and industrial-grade ICs.

The TLC1549 family was designed for cost-sensitive, medium-speed data acquisition in industrial and embedded systems-emphasizing ease of integration, robust serial interface, and inherent sample-and-hold functionality without external components.

FAQ

What is the maximum clock frequency supported by the TLC1549CDG4?

The TLC1549CDG4 supports a maximum I/O CLOCK frequency of 2.1 MHz under recommended operating conditions (VCC = 4.5–5.5 V, TA = 0°C to 70°C). Exceeding this limit may cause timing violations, incomplete sampling, or invalid conversion results. The device's internal logic requires minimum pulse widths of 190 ns for both high and low states, consistent with this 2.1 MHz ceiling. This specification is explicitly stated in the "Recommended Operating Conditions" table of the SLAS059C datasheet.

Does the TLC1549CDG4 require an external sample-and-hold circuit?

No, the TLC1549CDG4 includes an inherent sample-and-hold function implemented via its switched-capacitor architecture. Sampling occurs automatically between the third and tenth falling edges of the I/O CLOCK signal, and the sampled value is held for conversion. No external components are needed-this is confirmed in the device description, functional block diagram, and timing diagrams (Figures 6–11) of the SLAS059C datasheet.

What are the absolute maximum ratings for the analog input voltage of the TLC1549CDG4?

The absolute maximum analog input voltage for the TLC1549CDG4 is –0.3 V to VCC + 0.3 V, as specified in the "Absolute Maximum Ratings" table of SLAS059C. Operation outside this range risks permanent damage. For safe and specified operation, the analog input must remain between 0 V and VCC (with VCC = 4.5–5.5 V), and must not exceed the differential reference voltage (VREF+ – VREF–), which is rated from 2.5 V to VCC+0.2 V.

Is the TLC1549CDG4 pin-compatible with the TLC549 series?

Yes, the TLC1549CDG4 is terminal-compatible with the TLC549 series, meaning identical pin assignments, electrical behavior, and timing relationships for CS, I/O CLOCK, and DATA OUT. This compatibility is explicitly stated in the datasheet introduction and confirmed by matching pin functions and top-view diagrams for D-package variants. However, note that TLC549 is an 8-bit device, so firmware must accommodate the extended 10-bit word length.

What is the purpose of the REF– pin on the TLC1549CDG4?

The REF– pin on the TLC1549CDG4 serves as the lower reference voltage input, establishing the zero-scale point of the ADC transfer function. When paired with REF+, it defines the full-scale input range (VREF+ – VREF–). This differential configuration enables ratiometric measurements-critical for sensor interfaces where excitation voltage drift would otherwise degrade accuracy. The datasheet specifies REF– can be tied to GND or a negative bias up to –0.1 V absolute maximum.