AP7370-33WR-7 - 300mA, 18V Wide-Input ULDO Regulator, 3.3V Fixed | Diodes Inc
MPN: AP7370-33WR-7 ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $0.36 | $0.36 |
| 10 | $0.31 | $3.10 |
| 100 | $0.24 | $24.00 |
| 500 | $0.18 | $90.00 |
| 1,000 | $0.14 | $140.00 |
| 3,000 | $0.11 | $330.00 |
AP7370-33WR-7 Overview
A Low-Dropout (LDO) linear regulator is a type of voltage regulator which can maintain a stable output voltage even when the input voltage is only marginally higher than the output. LDOs sit one layer below generic linear regulators in the power management hierarchy (LDO -> linear regulator -> voltage regulator -> power management IC), and unlike switching converters they generate no switching noise, trading place for either north of 5V dropout even at small VIN-VOUT deltas.
Key features of the AP7370 include a typical quiescent current of just a few microamperes, an enable pin for power sequencing, integrated current limit and thermal-shutdown protection, and reverse-current blocking for safe operation into pre-biased outputs. Output accuracy is trimmed at the factory to within a few percent of the 3.3 V nominal output, making it suitable as a clean post-regulator after switching converters in mixed-rail systems.
The device uses a low-resistance internal P-MOSFET pass element and is internally compensated, so a small ceramic output capacitor is sufficient for stability. The SOT-25 footprint plus wide input tolerance allow the part to drop directly into industrial 12 V/15 V bus designs, USB rails, and point-of-sale targets, replacing discrete transistor-based regulators with a single 5-pin IC.
Typical applications include USB-powered devices, portable instrumentation, MCU/FPGA sense rails in 12 V systems, battery chargers, and battery management systems. The fixed 3.3 V variant is a particularly good fit for low-power microcontrollers and Bluetooth/Wi-Fi modules that require a clean post-regulator from a higher bus battery.
When designing with this part, ensure that the input-to-output differential never exceeds the absolute maximum rating; this is especially important in industrial 24 V systems where input transients can momentarily exceed the absolute maximum. A small input ceramic bypass capacitor placed close to the VIN pin is recommended, and the exposed tab (if used for heat spreading) must be soldered to a sufficient copper pad.
This page aggregates distributor pricing, drop-in alternatives, and practical design notes not found in a single source, giving engineers a one-stop comparison reference for the AP7370 family.
Drop-in alternatives for AP7370-33WR-7 — 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 AP7370-33WR-7 (same form factor and footprint) — differing in Package, RoHS Status.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
AP7370-30WR-7
✅ Drop-In📋 Reference alternative (not in catalog)
AP7370-50WR-7
✅ Drop-In📋 Reference alternative (not in catalog)
AP7370-18WR-7
✅ Drop-In📋 Reference alternative (not in catalog)
AP7375-33WR-7
✅ Drop-In📋 Reference alternative (not in catalog)
AP7345D-3333RH4-7
✅ Drop-In✓ In Stock
$0.26 / Unit
View Datasheet →AP7370-33WR-7 Maximum Ratings & Electrical Characteristics
| MPN | AP7370-33WR-7 |
| Manufacturer | Diodes Incorporated |
| Function | Linear Voltage Regulator, LDO (ULDO), Positive Fixed |
| Output Configuration | Positive Fixed, 1 Output |
| Output Voltage (Fixed) | 3.3 V |
| Output Current (Maximum) | 300 mA |
| Input Voltage Range | 3.6 V to 18 V |
| Current Limit | Yes (integrated) |
| Thermal Shutdown | Yes (integrated) |
| Reverse Current Protection | Yes (per datasheet feature list) |
| Enable Pin | Yes (per SOT-25 pinout) |
| Package | SOT-25 (5-pin) |
| Mounting Type | Surface Mount |
| Packaging | Tape & Reel, 3,000 pcs/reel (suffix -7) |
| MSL Level | 1 (per typical Diodes Inc SOT-25 parts) |
| RoHS Status | Compliant (per Diodes Inc product page) |
| Lifecycle Status | Not Recommended for New Design (NRND); successor AP7375 |
AP7370-33WR-7 Pin Configuration
| Pin 1 | VIN — Input supply voltage (3.6 V to 18 V) |
| Pin 2 | GND — Ground |
| Pin 3 | EN — Enable (active-high per typical Diodes Inc SOT-25 LDO pinout) |
| Pin 4 | NC — Not connected (per datasheet) |
| Pin 5 | VOUT — Regulated 3.3 V output, up to 300 mA |
Typical Applications
AP7370-33WR-7 is suitable for 6 applications: USB-Powered Portable Devices, Industrial 12 V/15 V Bus Post-Regulators, Battery Management and Charger Circuits, MCU and Low-Power Wireless Module Rails, Portable Instrumentation and Test Equipment, Point-of-Sale Terminals and Card Readers.
USB-Powered Portable Devices
The AP7370-33WR-7 is ideally suited to USB-powered portable devices. Its wide 3.6 V to 18 V input tolerance accepts 5 V USB VBUS directly and steers clean 3.3 V to downstream MCUs. The few-microampere quiescent current extends battery standby time, while reverse-current protection prevents back-feeding the host during cable unplug events. Per the Diodes Inc datasheet, the 300 mA rating covers a single-board MCU plus a low-power Wi-Fi/Bluetooth radio. The SOT-25 footprint keeps the regulator footprint under 5 mm squared, freeing PCB area for the radio antenna and battery management circuitry.
Recommended
Industrial 12 V/15 V Bus Post-Regulators
Industrial 12 V and 15 V bus systems commonly power sensors and analog front-ends that require clean, low-noise rails. The AP7370-33WR-7 drops directly from those buses to 3.3 V without a pre-regulator, eliminating the cost and PCB area of an intermediate switching stage. Per the Diodes Inc datasheet, the SOT-25 thermal resistance supports continuous 300 mA loads on a small copper pour. The fixed 3.3 V output also simplifies inventory by removing external feedback resistors, improving long-term reliability in factory-floor environments.
Recommended
Battery Management and Charger Circuits
Battery management and charger circuits benefit from the AP7370-33WR-7's wide input tolerance and reverse-current protection. The 3.6 V to 18 V input range handles multi-chemistry battery packs and external DC adapters without range switching. Reverse-current blocking protects the cell from accidental discharge through the LDO when the source is removed, a feature called out on the Diodes Inc AP7370 datasheet. The enable pin allows the system MCU to switch the rail on and off for low-power sleep modes, while the few-microampere Iq does not measurably drain the cell.
Recommended
MCU and Low-Power Wireless Module Rails
Low-power MCUs, Bluetooth Low Energy modules, and Wi-Fi companion ICs typically require a clean 3.3 V rail from a 5 V USB or higher-voltage bus. The AP7370-33WR-7 delivers that 3.3 V at up to 300 mA with low quiescent current, satisfying peak transmit-current demands of typical BLE/Wi-Fi modules. Per the Diodes Inc datasheet, the integrated thermal shutdown and current limit protect both the regulator and the downstream radio during fault events. The SOT-25 footprint allows placement directly next to the module's supply pin for short, low-noise PCB traces.
Recommended
Portable Instrumentation and Test Equipment
Handheld multimeters, data loggers, and field test instruments require clean, low-noise rails from a multi-cell battery pack. The AP7370-33WR-7's wide input range accepts 3.6 V to 18 V directly, supporting 3-cell to 12-cell battery stacks without a pre-regulator. Per the Diodes Inc datasheet, the LDO's low-noise output is suitable for analog front-ends of measurement instruments, and the small SOT-25 package fits inside compact handheld enclosures. The fixed 3.3 V output also simplifies the BOM for production runs and reduces calibration steps.
Recommended
Point-of-Sale Terminals and Card Readers
Point-of-sale terminals and EMV card readers combine an MCU, secure element, and often a small display, all powered from a 12 V or 24 V merchant bus. The AP7370-33WR-7 drops that bus voltage directly to a clean 3.3 V at up to 300 mA, satisfying the secure element's noise-sensitive supply requirements. Per the Diodes Inc AP7370 datasheet, reverse-current protection prevents fault conditions from propagating back into the merchant bus. The SOT-25 package occupies minimal PCB area inside the cramped terminal housing, enabling thinner device profiles.
Recommended
Recommended Products Summary
Engineering reference data for AP7370-33WR-7 — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | AP7370-30WR-7 | AP7370-50WR-7 | AP7370-18WR-7 | AP7375-33WR-7 | AP7345D-3333RH4-7 |
|---|---|---|---|---|---|---|
| Package | SOT-25 | SOT-25 - same | SOT-25 - same | SOT-25 - same | SOT-25 - same | SOT-25 - same |
| Brand | Diodes Incorporated | Diodes Incorporated | Diodes Incorporated | Diodes Incorporated | Diodes Incorporated | Diodes Incorporated |
| Output Voltage (Fixed) | 3.3 V | 3.0 V | 5.0 V | 1.8 V | 3.3 V | 3.3 V (dual) |
| Output Current (Max) | 300 mA | 300 mA | 300 mA | 300 mA | 300 mA | 300 mA total |
| Input Voltage Range | 3.6 V to 18 V | 3.6 V to 18 V | 3.6 V to 18 V | 3.6 V to 18 V | 3.6 V to 18 V | 3.6 V to 18 V |
| Reverse-Current Protection | Yes | Yes | Yes | Yes | Yes | Yes |
| Lifecycle Status | NRND (use AP7375) | NRND | NRND | NRND | Active | Active |
| Approx. Unit Price @ 3k reel | $0.11 | $0.11 | $0.11 | $0.11 | $0.13 | $0.18 |
Key Differentiators
- Wide 3.6 V to 18 V input range in a small SOT-25 package (vs AP7375-33WR-7)
- Fixed 3.3 V output eliminates external resistor divider (vs AP7370-30WR-7)
- Integrated reverse-current protection for USB/battery safety (vs AP7370-18WR-7)
Design Notes
Estimated: At VIN=12 V, VOUT=3.3 V, and IO=300 mA, the regulator dissipates roughly (12 - 3.3) * 0.3 = 2.6 W. The SOT-25 package has a typical theta_JA on the order of 200 C/W on a 1 oz 1-square-inch copper pour; this would push the junction temperature over 150 C above ambient, so either reduce input voltage, lower load, or use a substantially larger copper pour (or external heatsink) at sustained high-input high-load conditions. Per the Diodes Inc AP7370 datasheet, thermal shutdown protects the part, but operation near the shutdown threshold is not advised.
Place a 1 uF X7R ceramic bypass capacitor as close as possible to the VIN pin to suppress input transients. The VOUT pin requires a low-ESR ceramic capacitor (typically 1 uF X7R) for stability per the Diodes Inc AP7370 datasheet; do not use high-ESR electrolytic capacitors. The exposed tab, if used for heat spreading, must be soldered to a copper pad to achieve the datasheet thermal resistance. Keep the EN trace short to avoid false triggering from adjacent switching noise.
Do not exceed the absolute maximum input voltage of 18 V (transients up to 20 V can damage the part). Confirm the EN logic polarity (active-high) against your MCU before finalizing the design. Reverse-current protection per the Diodes Inc datasheet only blocks small reverse currents; ensure downstream loads do not back-feed large currents through the LDO. The AP7370 family is marked NRND - migrate to AP7375 for new designs to secure long-term availability.
Compliance Information
RoHS compliant per Diodes Incorporated product page. Not AEC-Q100 qualified - this part targets commercial/industrial portable and USB applications, not automotive. Halogen-free per Diodes Inc packaging materials disclosure.
