FUSB303 - Autonomous USB Type-C Port Controller, 15W | onsemi
MPN: FUSB303 ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $1.85 | $1.85 |
| 10 | $1.62 | $16.20 |
| 100 | $1.35 | $135.00 |
| 500 | $1.12 | $560.00 |
| 1,000 | $0.94 | $940.00 |
| 3,000 | $0.78 | $2,340.00 |
FUSB303 Overview
A USB Type-C port controller is a specialized interface IC that manages the Configuration Channel (CC) pins and advertises the port's role (Source, Sink, or DRP) over the USB-C receptacle. It sits hierarchically between the physical USB-C connector, the system power management, and the application processor, and falls under the broader categories of interface ICs, USB controllers, and protocol controllers within a USB-C subsystem.
Key features of the FUSB303 include ultra-low standby current, integrated CC line pull-up (Rp) and pull-down (Rd) resistors, automatic DRP toggle, Try.SNK / Try.SRC support, and detection of audio adapter accessories and debug accessories. The device supports USB Type-C R1.3 attach/detach signaling and reports the detected port role via I2C registers or the GPIO output. The 12-X2QFN package (1.6 x 1.6 mm, 0.4 mm pitch) makes it suitable for space-constrained mobile and wearable designs.
Technically, the FUSB303 integrates analog CC comparators with hysteresis, a precision current source for Rp assertion, and a state machine implementing USB-C attach, detach, and Error Recovery transitions. The I2C interface supports standard (100 kHz) and fast (400 kHz) modes and four selectable 7-bit addresses, allowing up to four FUSB303 devices on one bus for multi-port systems.
Typical applications include USB-C wall chargers, USB-C cable adapters, OTG dongles, tablets, smartphones, wearables, docking stations, and 15 W or less charging sinks and sources. The autonomous operation mode removes firmware dependency on the host MCU for basic CC detection.
When designing with the FUSB303, pay attention to CC pull-up source current accuracy, VDD decoupling, and bypass capacitance on the connector side. Designers transitioning from FUSB303 to FUSB303B should review Error Recovery behavior since the B variant removes the Error Recovery state transition during mode changes.
This page synthesizes distributor pricing, same-brand drop-in alternatives, and practical design notes not found in the onsemi datasheet alone.
Drop-in alternatives for FUSB303 — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with FUSB303 (same form factor and footprint) — differing in Function, Interface.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
FUSB303BTMX
✅ Drop-In📋 Reference alternative (not in catalog)
FUSB303TMX
✅ Drop-In✓ In Stock
$0.52 / Unit
View Datasheet →FUSB303BTMX
✅ Drop-In📋 Reference alternative (not in catalog)
FUSB303 Specifications
| Function | USB Type-C Port Controller |
| Protocol | USB Type-C |
| USB Version | USB 2.0 / USB 3.1 (sideband use only) |
| Role Support | Source, Sink, DRP, Accessory detection, Dead Battery |
| Maximum Power | 15 W |
| Interface | I2C (configurable address) + GPIO |
| I2C Addresses | 4 selectable 7-bit addresses |
| I2C Speed | Standard 100 kHz / Fast 400 kHz |
| Supply Voltage (VDD) | 3.0 V to 5.5 V |
| Standby Current | Ultra-low (per datasheet) |
| Package | 12-X2QFN (1.6 x 1.6 mm) |
| Pin Pitch | 0.4 mm |
| Mounting Type | Surface Mount |
| Operating Temperature | -40 C to +85 C |
| RoHS Status | Compliant |
FUSB303 Pin Configuration
| Pin 1 | CC1 — Configuration Channel 1 - USB-C CC pin, integrated Rp/Rd |
| Pin 2 | CC2 — Configuration Channel 2 - USB-C CC pin, integrated Rp/Rd |
| Pin 3 | GND — Ground reference |
| Pin 4 | VDD — Supply input, 3.0 V to 5.5 V |
| Pin 5 | SDA — I2C data line (open-drain, requires pull-up) |
| Pin 6 | SCL — I2C clock line (open-drain, requires pull-up) |
| Pin 7 | INT_N — Interrupt output (active low) / GPIO configurable |
| Pin 8 | GPIO — General purpose I/O / status output |
| Pin 9 | ADDR0 — I2C address select bit 0 |
| Pin 10 | ADDR1 — I2C address select bit 1 |
| Pin 11 | MODE0 — Role configuration strap 0 (Source/Sink/DRP) |
| Pin 12 | MODE1 — Role configuration strap 1 (Source/Sink/DRP) |
Typical Applications
FUSB303 is suitable for 6 applications: USB-C Wall Charger (Source), USB-C Cable Adapter / Dongle, Tablet and Smartphone Charging Port, Wearable Charging Cradle, USB-C Docking Station, USB-C Audio Accessory Adapter.
USB-C Wall Charger (Source)
The FUSB303 implements the Source role on a USB-C charging adapter, advertising 5 V Default USB Power on the CC lines via its integrated Rp current source. With 15 W maximum power and autonomous pin-strapped operation, the FUSB303 eliminates firmware on the charger's MCU and reduces BOM cost. The 12-X2QFN (1.6 x 1.6 mm) footprint allows ultra-slim wall-wart designs. Pair the FUSB303 with a buck converter for VBUS regulation and an opto-isolated feedback path for isolated chargers.
Recommended
USB-C Cable Adapter / Dongle
The FUSB303 is well-suited for USB-C-to-legacy adapters, dongles, and OTG cables where the host or device side needs explicit Sink or DRP role detection. Its low standby current preserves battery life in mobile adapters, and the 1.6 x 1.6 mm X2QFN package fits inside connector shells. The autonomous attach/detach behavior, with optional I2C override, gives designers a flexible path for both dumb dongles and smart hubs. Compared to discrete CC logic, FUSB303 saves PCB area and design time.
Recommended
Tablet and Smartphone Charging Port
The FUSB303 supports the Sink role on tablets and smartphones drawing power up to 15 W over USB-C. Dead Battery support per the USB-C spec allows a depleted device to be detected as a Sink even when its main MCU is off, enabling safe charging from any Type-C source. With 4 selectable I2C addresses, up to four ports (charger input, accessory port, etc.) can share one bus. The 12-X2QFN package fits the tight PCB stack-up of modern smartphones.
Recommended
Wearable Charging Cradle
Wearables such as smartwatches and fitness bands use small USB-C or pogo-pin cradles where the FUSB303's tiny 1.6 x 1.6 mm X2QFN footprint and ultra-low standby current are critical. The device's autonomous Sink detection allows the wearable's battery to charge without waking the host MCU, extending standby time. DRP toggle support lets the cradle act as either source or sink depending on the upstream device. Designers benefit from I2C-based status reporting to log charge events.
Recommended
USB-C Docking Station
The FUSB303 can serve as a downstream USB-C port controller on docking stations, advertising Sink role and requesting 5 V up to 3 A from the host laptop or tablet. Multi-port docking benefits from the FUSB303's four selectable I2C addresses, allowing one MCU to manage up to four CC controllers on the same bus. The integrated CC comparators and pull-up/pull-down resistors remove the need for external analog components, simplifying dock-side schematics.
Recommended
USB-C Audio Accessory Adapter
USB-C audio adapters rely on detecting analog audio accessory modes, and the FUSB303 supports accessory detection including audio adapter and debug accessory per the USB-C specification. By handling CC attach/detach and accessory state reporting autonomously, the FUSB303 removes host-MCU firmware dependencies for accessory recognition. Its 1.6 x 1.6 mm package fits inline between the USB-C connector and the DAC/headphone amplifier PCB.
Recommended
Recommended Products Summary
Engineering reference data for FUSB303 — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | FUSB303BTMX | FUSB302TMPX |
|---|---|---|---|
| Brand | onsemi | onsemi | onsemi |
| Package | 12-X2QFN (1.6x1.6 mm) | 12-X2QFN (1.6x1.6 mm) - same | 14-TMLP - different package |
| Function | USB Type-C Port Controller (autonomous) | USB Type-C Port Controller (autonomous) | USB Type-C Port Controller (programmable) |
| Maximum Power | 15 W | 15 W | 100 W (PD-capable) |
| Role Support | Source / Sink / DRP / Accessory / Dead Battery | Source / Sink / DRP / Accessory / Dead Battery | Source / Sink / DRP + PD messaging |
| Interface | I2C (4 selectable) + GPIO | I2C (4 selectable) + GPIO | I2C + GPIO |
| Error Recovery Transition | Yes (every mode change) | No (removed in B variant) | Configurable |
| Supply Voltage | 3.0 V to 5.5 V | 3.0 V to 5.5 V | 2.7 V to 5.5 V |
Key Differentiators
- Autonomous pin-only operation requires no host MCU (vs FUSB302TMPX)
- Compact 12-X2QFN 1.6x1.6 mm footprint (vs FUSB302TMPX (14-TMLP))
- Lower-cost solution for sub-15 W designs (vs FUSB302TMPX (PD-capable))
Design Notes
Decouple VDD with a 1 uF X7R ceramic capacitor placed within 3 mm of the VDD pin. The FUSB303 draws very low standby current, but CC line transitions can induce brief VDD transients. A bulk 10 uF on the upstream 5 V rail further reduces the effect of VBUS hot-plug events on the FUSB303 supply.
Route CC1 and CC2 as a 90-ohm differential pair with no stubs, keeping traces short and matched within 0.5 mm. Place the FUSB303 as close as practical to the USB-C connector to minimize CC trace length; every 10 mm of trace adds measurable capacitance that can shift Rp timing.
Do not pull CC lines high externally - the FUSB303 integrates Rp/Rd and external resistors will distort detection. When migrating from FUSB303 to FUSB303B, validate that mode-change detach detection no longer occurs; some firmware relying on Error Recovery transition must be updated.
Estimated: the FUSB303 dissipates less than 50 mW in normal operation. With theta_JA of approximately 80 C/W for the 12-X2QFN package on a 4-layer 1 oz PCB, the junction rise is under 4 C - no heatsink required. For enclosed adapters above 60 C ambient, add thermal vias under the exposed pad.
Compliance Information
RoHS and REACH compliant per onsemi product page. Consumer-grade temperature range; not AEC-Q100 qualified.
