Texas Instruments LT1054CDW

Overview

LT1054CDW from Texas Instruments is a bipolar switched-capacitor voltage converter with integrated regulation, delivering up to 100 mA output current at ≤1.6 V voltage loss across 3.5–15 V input range. It features an internal 2.5 V reference, external shutdown via FB/SD pin, and oscillator synchronization capability. It is used in RS-232 interface supplies requiring stable negative rail generation.

For engineers reviewing the LT1054CDW datasheet, LT1054CDW pinout, LT1054CDW application, or LT1054CDW equivalent, key selection criteria include regulated negative output capability, 100 mA load support, shutdown quiescent current of 100 µA, oscillator frequency adjustability (15–35 kHz), and SOIC-16 package compatibility with thermal resistance of 57 °C/W.

Technical Context

The LT1054CDW implements a charge-pump topology with adaptive-switch drive to minimize conduction losses across varying load currents. Its error amplifier compares feedback from an external resistor divider against a trimmed 2.5 V internal reference, enabling precise output regulation independent of input voltage or load variation.

It operates with a nominal 25 kHz internal oscillator, configurable via the OSC pin for frequency tuning or external synchronization. Shutdown is asserted by pulling the FB/SD pin below ≈0.45 V, disabling switching and reducing supply current to 100 µA while discharging external capacitors through the load.

Key Specifications

Pinout & Package

LT1054CDW is housed in a 16-pin SOIC (DW) package measuring 10.30 mm × 10.30 mm, with exposed pad not present and standard JEDEC MS-013AC footprint.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar switched-capacitor voltage converter applications.

Compared with LT1054CDW, LT1054CN8 offers identical functionality in a thermally less efficient package, while LTC1044CSW provides basic inversion without regulation-requiring external circuitry for stable output, making LT1054CDW the sole choice for integrated, 100 mA regulated negative rail generation in SOIC-16 format.

Availability

LT1054CDW is available at Aetrix Electronics and suitable for industrial communications (RS-232), data acquisition front-ends, and voltage inverter applications requiring stable component supply, long-term lifecycle assurance, and traceable sourcing.

Supply support for LT1054CDW 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 company headquartered in Dallas, Texas, designing and manufacturing analog ICs, embedded processors, and digital signal solutions for industrial, automotive, and communications markets.

The LT1054 product line was developed specifically for high-efficiency, regulated negative voltage generation in space-constrained analog systems-targeting applications where transformerless, low-noise, and programmable rail generation is essential.

FAQ

What is the maximum output current capability of the LT1054CDW under regulated conditions?

The LT1054CDW delivers up to 100 mA of continuous regulated output current when operating within its recommended input voltage range (3.5 V to 15 V) and junction temperature limits. This rating assumes proper external capacitor selection (e.g., 100 µF tantalum for C_OUT), adequate PCB copper for thermal dissipation, and ambient temperature ≤70°C. At 100 mA, voltage loss remains ≤1.6 V, ensuring stable regulation for –5 V or similar outputs.

How does the LT1054CDW achieve output voltage regulation without an external op-amp?

The LT1054CDW achieves regulation using an integrated 2.5 V precision reference and error amplifier. The FB/SD pin serves as the inverting input to this amplifier. By connecting an external resistor divider from VOUT to GND-with the midpoint fed to FB/SD-the device compares the scaled output against the internal reference and adjusts switch duty cycle to maintain regulation. This eliminates the need for external compensation components or op-amps typically required in discrete charge-pump designs.

Can the LT1054CDW be synchronized to an external clock, and how is this implemented?

Yes, the LT1054CDW can be synchronized to an external clock via the OSC pin (Pin 13). This is accomplished by connecting an open-collector or NPN transistor output to OSC, with a 20 kΩ pull-up to VREF (Pin 12). The external clock drives the oscillator node directly, overriding the internal timing capacitor. Synchronization prevents EMI beat frequencies in multi-converter systems and enables deterministic noise placement-critical in mixed-signal applications like data acquisition where switching artifacts must avoid ADC sampling bands.

What is the purpose of the VREF pin on the LT1054CDW, and what load can it drive?

The VREF pin on the LT1054CDW provides a stable 2.5 V ±0.25 V reference voltage derived from an internal bandgap circuit. It serves two roles: (1) as the reference for the internal error amplifier during regulation, and (2) as a precision external reference for feedback networks or auxiliary circuitry. The datasheet specifies a maximum load of 60 µA for regulation accuracy; exceeding this may cause reference droop and output voltage error. Shorting VREF to GND draws ~100 µA and does not damage the device, allowing safe use as a pull-up point in sync configurations.

Is the LT1054CDW pin-compatible with the LTC1044, and what are the key functional differences?

The LT1054CDW is pin-to-pin compatible with the LTC1044 in SOIC-16 packaging, sharing identical pin numbering and physical layout. However, key functional differences exist: the LT1054CDW adds internal regulation (via FB/SD and VREF), supports 100 mA vs. 50 mA output, includes shutdown capability, and features adaptive-switch drive for improved efficiency. The LTC1044 lacks regulation circuitry entirely and cannot generate programmable or stabilized negative outputs without external components-making the LT1054CDW a functional superset for regulated applications.