onsemi CAT6243-ADJCMT5T

Overview

CAT6243-ADJCMT5T from onsemi is an adjustable low-dropout CMOS voltage regulator delivering up to 1 A output current with 350 mV typical dropout at full load, ±2.0% output voltage accuracy at room temperature, and stable operation with ceramic output capacitors. It serves as a core power supply for FPGA I/O rails, DSP cores, and mobile device subsystems requiring precise, low-noise, and fast-transient regulation.

For engineers reviewing the CAT6243-ADJCMT5T datasheet, pinout, applications, or equivalent options, key selection criteria include adjustable 0.8 V–5.0 V output range, WDFN-6 package thermal performance (R_JA = 55 °C/W), shutdown ground current ≤5 µA, and compatibility with 100 pF–470 pF bypass capacitors for noise reduction.

Technical Context

The CAT6243-ADJCMT5T implements a PMOS pass transistor architecture enabling ultra-low dropout and reverse-current blocking. Its internal error amplifier compares ADJ pin voltage against a 0.8 V reference, while enable logic controls activation via a 2.5 MΩ internal pull-down resistor and 1.6 V logic-high threshold.

Thermal protection triggers at 145 °C with 10 °C hysteresis, and current limiting caps output at 900 mA under short-circuit conditions. The BYP pin accepts 100–470 pF capacitors to reduce output noise by up to 45 µV_rms (BW = 10 Hz–100 kHz) without compromising stability.

Key Specifications

Pinout & Package

Package: WDFN-6 (3 mm × 3 mm, 0.95 mm pitch, exposed thermal pad). Pin 2 and the center pad are internally connected to GND for PCB-level heat dissipation and EMI control.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar adjustable LDO applications.

Compared with NCP1117DTAR5G and MCP1826T-ADJE/OT, CAT6243-ADJCMT5T uniquely combines WDFN-6 thermal efficiency, integrated BYP noise suppression, and active output discharge - making it optimal for portable, noise-sensitive, and thermally demanding applications where layout area and transient response are critical.

Availability

CAT6243-ADJCMT5T is available at Aetrix Electronics and suitable for FPGA power management, mobile phone subsystems, and DSP core supplies requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for CAT6243-ADJCMT5T 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

onsemi (formerly ON Semiconductor) is a global semiconductor supplier specializing in energy-efficient power management, analog, sensing, and connectivity solutions for automotive, industrial, cloud, and consumer markets.

CAT6243-ADJCMT5T belongs to onsemi's precision LDO voltage regulator product line, engineered for high-current, low-noise, and thermally robust power delivery in portable and embedded systems with stringent size and efficiency requirements.

FAQ

What is the minimum input voltage required for CAT6243-ADJCMT5T to regulate a 1.2 V output?

The minimum input voltage for CAT6243-ADJCMT5T is the greater of 1.8 V or (V_OUT + V_DO). At 1.2 V output and 1 A load, V_DO is 625 mV typical, so VIN must be ≥1.825 V. Per Table 4, the absolute minimum VIN is 1.8 V - thus 1.825 V governs. This ensures stable regulation without dropout-induced sag in battery-powered CAT6243-ADJCMT5T designs.

Can CAT6243-ADJCMT5T operate without an external bypass capacitor on the BYP pin?

Yes, CAT6243-ADJCMT5T operates fully functional without a BYP capacitor - it is optional. Omitting it yields faster turn-on time (230 µs vs. 1.6 ms) but increases output noise to ~45 µV_rms. For noise-critical analog rails, a 470 pF capacitor is recommended; for digital-only loads where speed matters more, leaving BYP open is valid and safe.

How does the ADJ pin function in CAT6243-ADJCMT5T, and what resistor values are recommended for a 3.3 V output?

The ADJ pin connects to the center of a resistor divider between VOUT and GND, referencing an internal 0.8 V bandgap. For 3.3 V output, use R2 = 8 kΩ (to ensure ≥100 µA divider current) and R1 = 25 kΩ per Equation 3: R1 = R2 × (V_OUT/0.8 V − 1). This achieves ±2% accuracy across temperature in CAT6243-ADJCMT5T applications.

Does CAT6243-ADJCMT5T provide reverse-current protection, and how is it implemented?

Yes, CAT6243-ADJCMT5T includes automatic reverse-current blocking: when V_OUT exceeds VIN, the internal PMOS pass transistor turns OFF, preventing backfeed. This is inherent to its architecture - no external components needed. It protects upstream supplies during hot-swap or power sequencing, a key safety feature confirmed in the CAT6243-ADJCMT5T block diagram and pin description.

What thermal design considerations apply to CAT6243-ADJCMT5T in its WDFN-6 package?

CAT6243-ADJCMT5T's WDFN-6 package requires the exposed thermal pad to be soldered to a PCB ground plane using ≥4 thermal vias. With 650 mm² (1 in²) of 1 oz copper, R_JA = 55 °C/W allows >1 W dissipation at 25°C ambient. Reduce copper area below 650 mm²? Refer to Figure 28 in the CAT6243-ADJCMT5T datasheet for derated R_JA values - undersized pads risk thermal shutdown.