onsemi CAT6243-ADJMT5T3

Overview

CAT6243-ADJMT5T3 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, energy-efficient regulation.

For engineers reviewing the CAT6243-ADJMT5T3 datasheet, pinout, applications, or equivalent options, key selection criteria include adjustable 0.8–5.0 V output range, WDFN-6 thermal performance (R_JA = 55°C/W), shutdown ground current ≤5 µA, and compatibility with 100 pF–470 pF BYP capacitors for noise reduction.

Technical Context

The CAT6243-ADJMT5T3 implements a CMOS-based LDO architecture with internal error amplifier, reference voltage (0.8 V at ADJ), and P-channel pass transistor enabling ultra-low quiescent current. Its enable logic supports active-high control with 2.5 MΩ internal pull-down, and integrated thermal shutdown (145°C) and current limiting (900 mA short-circuit) ensure robust fault handling.

It features a dedicated BYP pin for external noise-filtering capacitor (100–470 pF), ADJ pin for resistor-divider feedback (I_ADJ = 100 nA max), and reverse-current blocking between VOUT and VIN. The WDFN-6 package includes an exposed thermal pad internally connected to GND for PCB heat sinking.

Key Specifications

Pinout & Package

Package: WDFN-6 (3 mm × 3 mm, 0.95 mm pitch), thermally enhanced with exposed GND pad (Case 511AP). Pin 2 and Pin 6 are electrically tied to the exposed pad, which must be soldered to PCB ground plane for thermal and electrical integrity.

Key Features

Applications

Equivalent & Alternatives

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

Compared with NCP1117DTARKG and TPL7407LDR, the CAT6243-ADJMT5T3 uniquely combines 1 A adjustable output, WDFN-6 thermal efficiency, and BYP-enabled noise filtering-making it optimal for space-constrained, multi-voltage, low-noise embedded systems where flexibility and performance are prioritized over lowest unit cost.

Availability

CAT6243-ADJMT5T3 is available at Aetrix Electronics and suitable for FPGA power management, mobile device subsystems, and industrial embedded controllers requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for CAT6243-ADJMT5T3 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 focused on energy-efficient electronics, with leadership in power management, analog, sensors, and connectivity solutions.

The CAT6243-ADJMT5T3 belongs to onsemi's precision LDO regulator product line, designed specifically for high-current, low-noise, adjustable-power applications in portable, automotive, and industrial systems where thermal efficiency and voltage accuracy are critical.

FAQ

What is the minimum input voltage required for CAT6243-ADJMT5T3 to regulate a 1.2 V output?

The minimum input voltage for CAT6243-ADJMT5T3 is the greater of 1.8 V or (V_OUT + V_DO). For a 1.2 V output, typical dropout is 625 mV at 1 A (per Table 5), so minimum VIN = 1.2 V + 0.625 V = 1.825 V - exceeding the absolute minimum 1.8 V rating. Thus, 1.83 V is the practical minimum for full-load regulation. The CAT6243-ADJMT5T3 datasheet specifies this relationship explicitly in Table 4 and Figure 8.

Can CAT6243-ADJMT5T3 be used without connecting a capacitor to the BYP pin?

Yes, CAT6243-ADJMT5T3 operates fully functional without a BYP capacitor. The BYP pin may be left open or floating, but must never be grounded - doing so disrupts the error amplifier. Omitting the BYP capacitor increases output noise (e.g., 45 µV_rms becomes higher) and reduces PSRR at 1–20 kHz, but does not affect regulation stability or basic functionality. The CAT6243-ADJMT5T3 design intentionally supports this flexibility for cost- or space-constrained layouts.

What is the recommended resistor value for setting a 0.8 V output with CAT6243-ADJMT5T3?

For a 0.8 V output, the CAT6243-ADJMT5T3 requires connecting the ADJ pin directly to VOUT (R2 = 0 Ω), as specified in the Applications section. No external resistor divider is needed because the internal reference is 0.8 V. If a minimum load is required (e.g., to prevent leakage-induced voltage rise above 85°C), a parallel 8 kΩ resistor from VOUT to GND is recommended. This configuration is validated for CAT6243-ADJMT5T3 in Figure 27 and Equation 2 of the datasheet.

How does the thermal pad on the CAT6243-ADJMT5T3 WDFN-6 package connect electrically?

The exposed thermal pad on the CAT6243-ADJMT5T3 WDFN-6 package (Pin 2 and Pin 6 per Table 1) is internally connected to GND. It must be soldered to a PCB ground plane using multiple thermal vias to ensure both electrical grounding and effective heat dissipation. Improper connection - such as isolation or routing to non-ground nets - risks short circuits, degraded thermal performance (R_JA worsens beyond 55°C/W), and potential device failure. This GND tie is confirmed in the Pin Functions section and Package Dimensions drawing.

Does CAT6243-ADJMT5T3 provide reverse-current protection?

Yes, CAT6243-ADJMT5T3 includes inherent reverse-current protection: whenever VOUT exceeds VIN, the internal P-channel pass transistor turns off, preventing current flow from output to input. Additionally, an integrated discharge transistor pulls VOUT to GND during shutdown (when EN < 0.4 V), ensuring rapid, controlled rail collapse. This dual protection is documented in the VOUT pin description (page 11) and Figure 2 block diagram, and is a key reliability feature of the CAT6243-ADJMT5T3.