NCP4687DMX25TCG - 500mA, 2.5V LDO Regulator, XDFN-6 | onsemi
MPN: NCP4687DMX25TCG ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $0.32 | $0.32 |
| 10 | $0.29 | $2.90 |
| 100 | $0.24 | $24.00 |
| 500 | $0.2 | $100.00 |
| 1,000 | $0.17 | $170.00 |
| 3,000 | $0.14 | $420.00 |
NCP4687DMX25TCG Overview
An LDO (Low-Dropout) linear regulator is a type of voltage regulator that maintains a stable output voltage even when the input voltage is very close to the output voltage, by using a CMOS or bipolar pass transistor that can operate with small input-to-output differentials. Within the broader power management hierarchy, an LDO is a subclass of linear regulator, which itself falls under voltage regulators, which are part of the power management IC (PMIC) family of semiconductors. LDOs are favored over switching regulators in noise-sensitive applications because they introduce no switching ripple, trading efficiency at large voltage drops for clean, low-noise output.
Key features include high PSRR for upstream switching-converter ripple rejection, low dropout for low-voltage headroom operation, integrated over-current and over-temperature shutdown protection, an active-high enable pin for power sequencing, and a built-in low-RDS(on) NMOS transistor for fast output capacitor discharge during shutdown. Output voltage accuracy is held within tight tolerances per the manufacturer datasheet (200 for NCP4687 series).
Technically the NCP4687DMX25TC uses a CMOS pass element rather than a bipolar transistor, which directly yields the low quiescent current (typically 1.0 uA) that makes it appropriate for portable, battery-powered systems. The integrated NMOS auto-discharge transistor quickly bleeds the output capacitor when the part is disabled, preventing residual voltage on the rail. The high PSRR at audio-band frequencies protects downstream analog blocks from upstream buck-converter switching ripple.
Typical applications include smartphone and wearable PMIC auxiliary rails, IoT sensor node power, portable medical monitoring electronics, automotive infotainment low-voltage rails, and as a post-regulator following a switching pre-regulator for noise-sensitive analog circuits.
When designing with this part, place a 1.0 uF ceramic input decoupling capacitor as close as possible to the input and ground pins per the datasheet, and use an equivalent low-ESR ceramic on the output. Do not omit the enable pin pull-down if unused.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet.
Drop-in alternatives for NCP4687DMX25TCG — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
NCP4687DMX18TCG
✅ Drop-In📋 Reference alternative (not in catalog)
NCP4687DMX33TCG
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NCP4687DMX28TCG
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
NCP4687DMX30TCG
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
NCP4687DMX12TCG
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
NCP170AMX250TCG
✅ Drop-In📋 Reference alternative (not in catalog)
NCP4687DMX25TCG Maximum Ratings & Electrical Characteristics
| Output Type | Fixed |
| Output Voltage | 2.5 V |
| Maximum Output Current | 500 mA |
| Dropout Voltage | 340 mV at 500 mA (typical) |
| Quiescent Current | 1.0 uA (typical) |
| PSRR | 75 dB at 1 kHz |
| Enable Pin | Yes (active-high) |
| Output Auto-Discharge | Yes (built-in low-RDS(on) NMOS) |
| Protection Features | Over-current, Over-temperature shutdown |
| Package | XDFN-6 (1.2 x 1.2 mm) with exposed pad |
| Mounting Type | Surface Mount |
| Lead Free | Yes |
| RoHS Status | Compliant |
NCP4687DMX25TCG Pin Configuration
| Pin 1 | VIN — Input voltage supply |
| Pin 2 | GND — Ground reference |
| Pin 3 | EN — Enable (active-high) |
| Pin 4 | NC — Not connected (per datasheet) |
| Pin 5 | VOUT — Regulated 2.5 V output |
| Pin 6 | NC — Not connected (per datasheet); exposed pad is thermal/ground |
Typical Applications
NCP4687DMX25TCG is suitable for 6 applications: Smartphone Always-On Auxiliary Rail, IoT Sensor Node Power, Portable Medical Monitoring Electronics, Automotive Infotainment Low-Voltage Rail, Post-Regulator for Switching Pre-Regulator, FPGA / MCU Core Voltage Rail.
Smartphone Always-On Auxiliary Rail
The NCP4687DMX25TCG's 2.5 V fixed output is well-matched to powering low-power always-on blocks in smartphones and wearables such as RTC backup domains, low-power MCUs, and sensor hubs. The 1.0 uA typical quiescent current minimizes sleep-mode drain, while the 500 mA capability provides headroom for active-mode transients. Placed near the PMIC output, it can post-regulate a switching rail down to a clean 2.5 V analog supply, with the high 75 dB PSRR at 1 kHz attenuating buck-converter switching ripple. The integrated NMOS auto-discharge transistor ensures the rail drops cleanly when the device is disabled, preventing back-powering through the load.
Recommended
IoT Sensor Node Power
Battery-powered IoT sensor nodes benefit from the NCP4687DMX25TCG's low quiescent current (1.0 uA typical) and 500 mA peak capability, allowing the same regulator to serve both sleep-state housekeeping loads and active radio transmit bursts. The 75 dB PSRR at 1 kHz ensures that noisy digital rails upstream do not couple into sensitive analog sensor front-ends. The XDFN-6 (1.2 x 1.2 mm) footprint is ideal for the small PCB area typical of coin-cell sensor nodes. Thermal performance is generally not a concern at low average currents in this application.
Recommended
Portable Medical Monitoring Electronics
The NCP4687DMX25TCG's 75 dB PSRR and clean LDO output make it appropriate for powering analog front-ends in portable medical monitors such as pulse oximeters, glucose meters, and ECG patches where rail noise directly impacts sensor accuracy. The 2.5 V output is compatible with common low-voltage AFE rails, while the 500 mA capability supports short active-mode measurement bursts. Low quiescent current extends battery life in continuous-wear devices. The exposed thermal pad supports sustained operation at higher ambient temperatures encountered in body-worn applications.
Recommended
Automotive Infotainment Low-Voltage Rail
Automotive infotainment head units and instrument clusters use the NCP4687DMX25TCG to provide a clean 2.5 V rail for audio CODECs, display controllers, and tuner modules where switching noise from upstream buck converters would degrade audio quality. The 75 dB PSRR and 500 mA output handle short audio peak transients. Although the base NCP4687DMX25TCG is not AEC-Q100 qualified, onsemi typically offers automotive-grade NCP4687 variants; engineers should verify automotive qualification status before designing the part into vehicle applications.
Recommended
Post-Regulator for Switching Pre-Regulator
The NCP4687DMX25TCG is commonly deployed as a post-regulator following a switching buck converter to provide a clean 2.5 V output where the high efficiency of a switching regulator is needed for the main voltage step-down but the final rail must be free of switching ripple. The 75 dB PSRR at 1 kHz attenuates the fundamental and harmonics of typical 1-2 MHz buck switching frequencies. The 500 mA output supports a wide range of analog and mixed-signal loads. Active-high enable allows coordinated power sequencing with the upstream switching converter.
Recommended
FPGA / MCU Core Voltage Rail
Low-power FPGA and MCU cores operating from a 2.5 V supply can use the NCP4687DMX25TCG as a local point-of-load regulator. The 500 mA capability supports medium-density FPGA core currents, while the fast transient response handles dynamic load steps from idle to active states. The exposed thermal pad allows direct soldering to inner PCB copper layers for thermal relief. The active-high enable pin enables sequenced power-up alongside other system rails, important for FPGA multi-rail sequencing requirements.
Recommended
Recommended Products Summary
Engineering reference data for NCP4687DMX25TCG — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | NCP4687DMX18TCG | NCP4687DMX33TCG | NCP4687DMX28TCG | NCP170AMX250TCG |
|---|---|---|---|---|---|
| Brand | onsemi | onsemi | onsemi | onsemi | onsemi |
| Package | XDFN-6 (1.2x1.2) | XDFN-6 (1.2x1.2) - same | XDFN-6 (1.2x1.2) - same | XDFN-6 (1.2x1.2) - same | XDFN-4 (1.0x1.0) - smaller |
| Output Voltage | 2.5 V | 1.8 V | 3.3 V | 2.8 V | 2.5 V |
| Maximum Output Current | 500 mA | 500 mA | 500 mA | 500 mA | 150 mA |
| Quiescent Current | 1.0 uA | 1.0 uA | 1.0 uA | 1.0 uA | 1.0 uA |
| Enable Pin | Yes (active-high) | Yes (active-high) | Yes (active-high) | Yes (active-high) | Yes (active-high) |
Key Differentiators
- Higher output current than NCP170 series (vs NCP170AMX250TCG)
- Integrated auto-discharge NMOS for fast output bleed (vs NCP170AMX250TCG)
- High 75 dB PSRR for upstream switching noise rejection (vs NCP170AMX250TCG)
Design Notes
Per the onsemi NCP4687 datasheet, place a 1.0 uF ceramic input decoupling capacitor as close as possible to the input and ground pins. Higher values and lower ESR improve line transient response. On the output, use a 1.0 uF or larger low-ESR ceramic capacitor to ensure the part meets its PSRR and load-step specifications. The NCP4687 is designed for ceramic output capacitors; do not substitute with high-ESR tantalum or aluminum types without verifying loop compensation.
The XDFN-6 (1.2 x 1.2 mm) package dissipates heat via the exposed thermal pad. At maximum 500 mA load and typical 3.6 V to 2.5 V step-down, power dissipation is approximately (3.6 V - 2.5 V) x 0.5 A = 0.55 W. Solder the exposed pad to a copper pour of at least 10 mm^2 on the top layer, with thermal vias to inner ground planes, to maintain junction temperature within safe limits. Without adequate copper, junction temperature may exceed 125°C at higher input rails.
Route the enable pin away from noisy switching traces; if unused, tie EN to VIN through a 100 kohm resistor or directly to VIN per datasheet. Keep the feedback and output sense path short and direct. The exposed pad must be soldered to the PCB ground plane to achieve the datasheet thermal resistance; dry or insufficient solder joints on the exposed pad can cause thermal shutdown under sustained load.
Do not assume the NCP4687DMX25 is AEC-Q100 qualified without checking the part marking and onsemi product page - the base commercial variant is typically not. For automotive designs, choose an AEC-Q100 qualified NCP4687 variant explicitly. Also note the part is marked obsolete on distributor sites, so for new designs, qualify an active NCP4687 family member or the NCP170 series now.
Compliance Information
RoHS compliant and lead-free per onsemi product page and chipdig.com. Base NCP4687DMX25TCG is not explicitly AEC-Q100 qualified - for automotive use, verify automotive-grade NCP4687 variants or consult onsemi.
