Microchip Technology TC1303A-ZI0EUN

Overview

TC1303A-ZI0EUN from Microchip Technology is a dual-output power management IC integrating a 500 mA synchronous buck regulator and a 300 mA low-dropout linear regulator (LDO), with power-good monitoring of the buck output only. It delivers 90% typical efficiency at 2.0 MHz switching frequency, features 65 µA total quiescent current, and supports fixed 1.2V/2.5V outputs in a 10-pin 3×3 mm DFN package. It is used in portable medical instruments requiring stable core and bias rails.

For engineers reviewing the TC1303A-ZI0EUN datasheet, TC1303A-ZI0EUN pinout, TC1303A-ZI0EUN application, or TC1303A-ZI0EUN equivalent, key selection criteria include buck/LDO output voltage pairing, PG monitoring scope (buck-only), independent shutdown control, thermal performance up to +125°C junction, and compatibility with 1 µF ceramic output capacitors on both rails.

Technical Context

The TC1303A-ZI0EUN implements a fixed-frequency 2.0 MHz PWM buck stage with automatic transition to PFM mode under light load to maintain ultra-low quiescent current. Its LDO stage uses internal compensation and achieves 137 mV dropout at 200 mA, enabling operation with minimal input–output differential.

Power-good logic monitors only the buck output (VOUT1) with 94% regulation threshold and 300 ms delay, generating an open-drain signal suitable for processor reset sequencing. UVLO activates at 2.55 V (typical) with 200 mV hysteresis, and thermal shutdown engages at 165°C with 10°C hysteresis.

Key Specifications

Pinout & Package

TC1303A-ZI0EUN is housed in a thermally enhanced 10-pin 3×3 mm DFN package with exposed pad (EP) connected to AGND. Pin 1 is SHDN2 (active-low LDO enable), Pin 2 is VIN2 (LDO input), Pin 3 is VOUT2 (LDO output), Pin 4 is PG (open-drain power-good), Pin 5 is AGND (analog ground), Pin 6 is PGND (power ground), Pin 7 is LX (buck switch node), Pin 8 is VIN1 (buck input), Pin 9 is SHDN1 (active-low buck enable), and Pin 10 is VFB1/VOUT1 (buck feedback or output).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual-output PMIC applications.

Compared with TC1303B-ZI0EUN and TC1303C-ZI0EUN, TC1303A-ZI0EUN offers buck-only PG assertion-ideal for cost-sensitive designs where core rail stability is the sole boot prerequisite and LDO serves non-critical loads.

Availability

TC1303A-ZI0EUN is available at Aetrix Electronics and suitable for handheld medical instruments, USB-powered devices, and cellular phones requiring stable component supply with guaranteed long-term availability and traceable sourcing.

Supply support for TC1303A-ZI0EUN 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

Microchip Technology is a leading provider of microcontrollers, analog, and Flash-IP solutions, serving automotive, industrial, consumer, and communications markets with high-reliability silicon and development tools.

The TC1303 family is designed for space-constrained portable electronics needing efficient, integrated dual-rail power conversion with precise sequencing and monitoring-targeting battery-operated medical, computing, and communication devices.

FAQ

What output voltages does the TC1303A-ZI0EUN provide?

The TC1303A-ZI0EUN provides two fixed output voltages: 1.2V on the buck regulator (VOUT1) and 2.5V on the LDO (VOUT2), as indicated by the "ZI0EUN" part number suffix per Microchip's ordering guide. Both outputs are internally set and require no external feedback resistors. The buck stage operates at 2.0 MHz and delivers up to 500 mA, while the LDO supplies up to 300 mA with 137 mV dropout at 200 mA load. TC1303A-ZI0EUN maintains these outputs across its full -40°C to +125°C junction temperature range.

How does the power-good (PG) function work on the TC1303A-ZI0EUN?

The TC1303A-ZI0EUN features an open-drain power-good output (Pin 4) that monitors only the buck regulator output (VOUT1). It asserts low when VOUT1 falls below 92% of nominal and releases high when VOUT1 rises above 94%, with 2% hysteresis. A built-in 300 ms delay ensures stable regulation before PG goes high-critical for reliable processor reset timing. Unlike TC1303B or TC1303C variants, TC1303A-ZI0EUN does not monitor the LDO output. This behavior is fixed per device variant and cannot be reconfigured.

Can the TC1303A-ZI0EUN operate from a single 3.3V input supply?

Yes, the TC1303A-ZI0EUN can operate from a single 3.3V input applied to both VIN1 and VIN2, as specified in Note 8 of the datasheet. At 3.3V input, the 1.2V buck output remains fully functional with >90% efficiency, and the 2.5V LDO output operates with 800 mV headroom-well above its 137 mV typical dropout voltage at 200 mA. Input voltage range is 2.7V to 5.5V, and undervoltage lockout disables both regulators if VIN drops below 2.55 V (typical). TC1303A-ZI0EUN maintains regulation and PG functionality across this entire range.

What is the thermal performance of the TC1303A-ZI0EUN in the 3×3 mm DFN package?

The TC1303A-ZI0EUN in its 10-pin 3×3 mm DFN package has a typical junction-to-ambient thermal resistance (θJA) of 41°C/W on a 4-layer PCB with internal ground plane and two vias under the exposed pad. At maximum 500 mA buck and 300 mA LDO load, power dissipation remains within safe limits up to +85°C ambient, and the device incorporates thermal shutdown at +165°C with 10°C hysteresis. The exposed pad must be soldered to AGND for optimal heat transfer. TC1303A-ZI0EUN is rated for continuous operation up to +125°C junction temperature.

Does the TC1303A-ZI0EUN support independent enable/disable of each output?

Yes, the TC1303A-ZI0EUN provides fully independent shutdown control: SHDN1 (Pin 9) enables/disables the buck regulator, and SHDN2 (Pin 1) enables/disables the LDO. Both are active-low logic inputs with thresholds defined as <15% VIN (low) and >45% VIN (high). This allows flexible power sequencing-for example, enabling the LDO first to power bias circuitry, then enabling the buck for core logic. TC1303A-ZI0EUN retains its 65 µA quiescent current specification only when both outputs are enabled; shutdown current drops to 0.05 µA typical with both SHDN pins grounded.