Texas Instruments TL499ACPG4

Overview

TL499ACPG4 from Texas Instruments is a dual-mode wide-range power-supply controller integrating an internal series-pass linear regulator and step-up switching regulator. It delivers adjustable regulated output from 2.9 V to 30 V, supports primary input (SERIES IN1) from 4.5 V to 32 V and secondary input (SW REG IN2) from 1.1 V to 10 V, and enables seamless switchover during AC-line failure-used in microprocessor memory backup systems.

For engineers reviewing the TL499ACPG4 datasheet, TL499ACPG4 pinout, TL499ACPG4 application, or TL499ACPG4 equivalent, key selection criteria include dual-input fault-tolerant regulation, externally set switching current via SW CURRENT CTRL pin, dropout voltage ≤1.8 V at 50 mA, thermal performance (RθJA = 110.7°C/W in SO-8), and operation across –20°C to +85°C.

Technical Context

The TL499ACPG4 operates in two mutually exclusive functional modes: linear regulation when SERIES IN1 is present (VI1 ≥ VO + dropout), and step-up switching regulation when SERIES IN1 is absent and SW REG IN2 supplies power. Its internal architecture integrates a reference amplifier, error comparator, series pass transistor, and switching power stage with integrated current-sense control.

Regulation is achieved via feedback to the REF pin using a resistor divider (e.g., RE1/RE2 = 4.7 kΩ), setting VO = VREF × (1 + RE1/RE2); VREF is trimmed to 1.26 V ±5% at 25°C. Switching current is controlled by a resistor from SW CURRENT CTRL to GND (RCL = 150–1000 Ω), directly scaling peak inductor current without external sensing.

Key Specifications

Pinout & Package

TL499ACPG4 is packaged in an 8-pin SOIC (SO-8, body size 6.20 mm × 5.30 mm), RoHS-compliant, with NIPDAU lead finish and MSL Level-1 rating. Pin 1 orientation follows Q1 quadrant per tape-and-reel standard.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual-mode power management applications.

Compared with LM2678-ADJ and TPS61040, TL499ACPG4 uniquely integrates both linear and switching regulation in one SO-8 package, enabling true fault-tolerant power delivery without external MOSFETs, diodes, or controllers-critical for space-constrained memory backup and industrial sensor designs.

Availability

TL499ACPG4 is available at Aetrix Electronics and suitable for microprocessor memory backup, battery-powered industrial sensors, voltage boosting for low-voltage sources, and dual-supply voltage regulation requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for TL499ACPG4 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 delivering analog and embedded processing solutions, with leadership in power management ICs since the 1970s.

The TL499A product line was designed specifically for fault-resilient power architectures-enabling reliable, adjustable DC-DC conversion in memory retention, telecom, and industrial control systems where input source redundancy is essential.

FAQ

What is the maximum output current capability of the TL499ACPG4 in series regulation mode?

The TL499ACPG4 delivers up to 100 mA continuous output current in series regulation mode, as specified under Recommended Operating Conditions. This limit is thermally constrained by the SO-8 package's RθJA of 110.7°C/W; at TA = 85°C and VO = 30 V, power dissipation must remain below ~350 mW to avoid junction temperature exceeding 150°C. Derating is required above 70°C ambient.

Can the TL499ACPG4 operate with a 1.2 V input on SW REG IN2 to generate 5 V output?

Yes, the TL499ACPG4 supports SW REG IN2 inputs as low as 1.1 V. With VI2 = 1.2 V and VO = 5 V, the minimum VO – VI2 differential (1.9 V at TA ≤ 85°C) is satisfied. Using RCL = 150 Ω and L = 50 µH, Table 1 confirms ≥20 mA output current is achievable-sufficient for low-power logic or RTC backup. Ensure CP = 0.01 µF and CF ≥ 330 µF for stability.

How does the TL499ACPG4 handle switchover between SERIES IN1 and SW REG IN2 inputs?

The TL499ACPG4 performs automatic, seamless switchover: when SERIES IN1 drops below VO + dropout (~1.8 V), the internal circuitry disables the series pass transistor and activates the switching regulator powered by SW REG IN2. No external control logic or sequencing is needed. Voltage deviation between modes is ≤30 mV/V, minimizing glitch risk to downstream circuitry.

What is the purpose of the SW CURRENT CTRL pin on the TL499ACPG4?

The SW CURRENT CTRL pin (Pin 4) accepts a resistor to GND (RCL) that directly programs the peak current limit of the internal switching transistor. Lower RCL values increase peak inductor current-e.g., RCL = 150 Ω yields ~500 mA, while RCL = 1 kΩ reduces it to ~100 mA. This allows designers to optimize inductor size, efficiency, and transient response without external current-sense components.

Is the TL499ACPG4 pin-compatible with earlier TL499A variants like TL499ACP or TL499ACPSR?

Yes, TL499ACPG4 shares identical pinout, electrical specifications, and SO-8 package dimensions with TL499ACPSR and TL499ACP. The "G4" suffix denotes TI's green packaging (lead-free, RoHS-compliant) and does not alter functionality or pin assignment. Layouts designed for TL499ACPSR are directly reusable for TL499ACPG4 without modification.