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NXP Semiconductors PCA9421UKZ
- Part No.:
- PCA9421UKZ
- Manufacturer:
- NXP Semiconductors
- Category:
- Power Management - Specialized
- Package:
- 25-UFBGA, WLCSP
- Datasheet:
-
PCA9421UKZ.pdf
- Description:
- IC PMIC WLCSP25
- Quantity:
- Payment:
- Shipping:
Inventory:2,896
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Product details
Overview
PCA9421UKZ from NXP Semiconductors is a highly integrated Power Management IC (PMIC) designed for low-power microcontroller systems, featuring two I²C-programmable buck converters (SW1: 0.5–1.5 V/1.8 V fixed, 250 mA; SW2: 1.5–2.1 V or 2.7–3.3 V, 500 mA), two programmable LDOs (LDO1: always-on, 1.7–1.9 V, 1 mA; LDO2: 1.5–2.1 V or 2.7–3.3 V, 250 mA), and Fm+ I²C interface up to 1 MHz - deployed in battery-powered IoT edge nodes and RT-series MCU platforms.
For engineers reviewing the PCA9421UKZ datasheet, PCA9421UKZ pinout, PCA9421UKZ application, or PCA9421UKZ equivalent, this page delivers verified regulator output ranges, WLCSP25 terminal mapping, thermal regulation thresholds (75–90 °C warning, 95–125 °C shutdown), I²C-configurable input current limiting (85–1105 mA), and mode-switching behavior across four register-defined power states - all confirmed from NXP's official Rev. 1.0 product data sheet.
Technical Context
The PCA9421UKZ implements dual independent buck regulators with integrated high-side/low-side MOSFETs and PFM control for light-load efficiency, plus two LDOs with separate input sourcing: LDO1 powered by the greater of ASYS or VBAT_BKUP (enabling coin-cell backup), LDO2 sourced solely from ASYS. All four regulators support on-the-fly voltage adjustment and per-rail enable/disable via I²C.
Its power sequencing is governed by a state machine with four programmable mode settings (0–3), each defining rail enablement, output voltages, watchdog timeout (disable/16/32/64 s), and thermal thresholds. Mode selection occurs via MODESEL0/MODESEL1 pins (when EN_MODE_SEL_BY_PIN_x = 1) or I²C registers, with ON-pin falling-edge triggering reset or full rail recycle based on long-press duration (4–16 s).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Buck1 Output | 0.5 V to 1.5 V in 25 mV steps + fixed 1.8 V; supports core rail for RT600/i.MXRT MCUs |
| Buck2 Output | 1.5 V to 2.1 V or 2.7 V to 3.3 V in 25 mV steps; supplies system voltage rails up to 500 mA |
| LDO1 Output | 1.70 V to 1.90 V in 25 mV steps; always-on supply for RTC/backup domain, max 1 mA |
| I²C Interface | Fm+ compliant, up to 1 MHz; enables dynamic rail reconfiguration without MCU reboot |
| Thermal Protection | Configurable shutdown threshold: 95–125 °C in 5 °C steps; warning at 75–90 °C |
| Input Current Limit | 8 selectable levels (85–1105 mA) or disable; applied only to VIN pin |
| Operating Temp | −40 °C to +85 °C ambient; validated for industrial-grade embedded deployment |
Pinout & Package
PCA9421UKZ is packaged in a 2.09 mm × 2.09 mm, 25-bump WLCSP with 0.4 mm pitch and 0.525 mm body height (SOT1401-4). The exposed pad must be connected to system ground.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN | Primary input supply | Bypassed with 2.2 µF/10 V capacitor; 20 V tolerant; source for ASYS when VIN_AUX is absent |
| ASYS | Bypassed system supply node | Input for PSYS1, PSYS2, and LDO2; powered by greater of VIN or VIN_AUX; requires 4.7 µF/10 V decoupling |
| VBAT_BKUP | Backup battery input | Source for LDO1 when higher than ASYS; connect to coin cell or tie to VIN_AUX if unused |
| SW1_OUT | Buck1 feedback node | Output of core buck regulator; bypassed with 10 µF/6.3 V capacitor; drives VDDCORE |
| LDO1_OUT | Always-on LDO output | 1.7–1.9 V rail for RTC/backup logic; max 1 mA; bypassed with 1 µF/6.3 V capacitor |
| SCL / SDA | I²C interface pins | Fm+ bus up to 1 MHz; require pull-up resistors (2.2–10 kΩ) to VDDIO_1 |
| ON | Power-enable input | Active-low with internal 1 MΩ pull-up; falling edge initiates power-up; long press (4–16 s) triggers full rail recycle |
| INTB | Interrupt output | Open-drain signal indicating thermal warning, UVLO, OVP, or watchdog expiry; requires external pull-up |
| SYSRSTn | System reset output | Open-drain reset asserted when any enabled rail deviates >10 % from target; tied to MCU RESETN |
Key Features
| Feature | Design Value |
|---|---|
| Dual buck + dual LDO integration | Reduces external component count: no external MOSFETs, drivers, or compensation networks required |
| Four independent power modes | Enables MCU runtime adaptation - e.g., Mode 0 (full performance), Mode 2 (ultra-low-power sleep) - with per-mode rail enable/voltage settings |
| Programmable thermal regulation | Independent 2-bit warning (75–90 °C) and 3-bit shutdown (95–125 °C) thresholds prevent thermal runaway in sealed enclosures |
| Backup-aware LDO1 | LDO1 remains active during main power loss using VBAT_BKUP, sustaining RTC and wake logic without MCU intervention |
| Active discharge control | Configurable bleeding resistors on all rails enable fast voltage ramp-down during mode transitions or shutdown sequences |
Applications
| Wearable Sensor Node | Industrial Edge Controller |
|---|---|
Use Scenario: Battery-powered BLE sensor hub with RT600 MCU, operating intermittently in deep-sleep mode with periodic wake-ups. IC Role / Device Role / Timing Role: PCA9421UKZ manages power sequencing, supplies VDDCORE (0.9 V) and VDDIO (3.3 V), maintains RTC via LDO1 during sleep, and signals wake events via INTB. Use Value: Achieves <1.5 µA quiescent current in standby; eliminates need for discrete LDOs and sequencers; extends coin-cell life beyond 5 years. |
Use Scenario: DIN-rail mounted PLC module with i.MXRT1064 MCU, requiring robust brown-out recovery and thermal margin in 70 °C ambient. IC Role / Device Role / Timing Role: PCA9421UKZ provides regulated 1.2 V core, 3.3 V I/O, and 1.8 V analog rails; monitors ASYS pre-warning and triggers SYSRSTn on UVLO. Use Value: Enables deterministic power-up sequence under fluctuating 24 V DC input; thermal warning interrupt allows firmware-initiated derating before shutdown. |
| Smart Home Hub | Medical Patch Monitor |
Use Scenario: Always-on Wi-Fi gateway with dual-core i.MXRT117x, switching between active streaming and low-power listening modes. IC Role / Device Role / Timing Role: PCA9421UKZ executes mode-switching: Mode 1 powers full CPU/cache (1.25 V), Mode 3 disables SW1 and lowers LDO2 to 1.8 V for RF-only operation. Use Value: Reduces system idle power by 42 % vs. fixed-rail PMIC; eliminates manual rail reconfiguration in firmware. |
Use Scenario: Disposable ECG patch with K4-family MCU, powered by single CR2032 and requiring >12-month shelf life. IC Role / Device Role / Timing Role: PCA9421UKZ delivers ultra-low-IQ LDO1 (1.8 V) for real-time clock and wake timer; uses VBAT_BKUP as primary LDO1 source during storage. Use Value: LDO1 leakage <100 nA ensures <0.5 % annual battery drain in storage; no external backup diode needed. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar power management IC applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS650361RGER | Single buck + triple LDO; no mode-switching; 2.5–5.5 V input; 1.2–3.3 V outputs; no backup LDO | Targeted at simpler MCU systems without dynamic voltage scaling or battery backup needs | Choose for cost-sensitive designs where rail count and sequencing complexity are lower |
| MCP16502-500/ADJ | Dual buck only (no LDOs); 0.6–3.6 V outputs; 1.2 A per channel; no I²C; fixed-frequency PWM only | Used in higher-current applications without low-noise analog or always-on domains | Prefer when core/system rails dominate load and LDO integration is unnecessary |
Compared with TPS650361RGER and MCP16502-500/ADJ, PCA9421UKZ uniquely combines dual buck + dual LDO + I²C-configurable multi-mode operation + backup-aware LDO1 in a 2.09 mm × 2.09 mm package - making it the only option for space-constrained, battery-backed, dynamically scaled MCU platforms like NXP's RT6xx series.
Availability
PCA9421UKZ is available at Aetrix Electronics and suitable for wearable sensor nodes, industrial edge controllers, smart home hubs, and medical patch monitors requiring stable component supply across extended temperature and lifecycle requirements.
Supply support for PCA9421UKZ 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
NXP Semiconductors is a global semiconductor leader focused on secure connectivity solutions for automotive, industrial, and IoT applications, with deep expertise in MCU-optimized power management.
The PCA9421UKZ belongs to NXP's dedicated PMIC portfolio for i.MXRT and K4-family MCUs, engineered to deliver tightly coupled, low-quiescent-power, multi-rail regulation with seamless mode transitions and battery-backup resilience.
FAQ
What is the maximum output current supported by the PCA9421UKZ's SW2 buck converter?
The PCA9421UKZ's SW2 buck converter delivers up to 500 mA continuous output current. This rail is configurable for either 1.5–2.1 V or 2.7–3.3 V ranges in 25 mV steps, supporting system-level I/O and peripheral power in compact MCU designs. Its current capability is validated under −40 °C to +85 °C ambient conditions with proper PCB layout and thermal management per NXP's SOT1401-4 package guidelines.
How does the PCA9421UKZ handle backup power for real-time clock functionality?
The PCA9421UKZ uses its LDO1 regulator - powered by the greater of ASYS or VBAT_BKUP - to maintain always-on 1.7–1.9 V supply for RTC circuits. When main power fails, LDO1 automatically switches to coin-cell input on VBAT_BKUP, sustaining timekeeping without MCU intervention. The LDO1 output is rated for up to 1 mA and exhibits <100 nA leakage in storage, ensuring multi-year battery shelf life.
Can the PCA9421UKZ operate without an external I²C host controller?
Yes - the PCA9421UKZ supports pin-strapped mode selection via MODESEL0/MODESEL1 and ON-pin control, enabling full power sequencing and rail configuration without I²C. Default Mode Setting 0 activates at power-up; long-press on ON (4–16 s, programmable) recycles rails to defaults. However, dynamic voltage adjustment, thermal threshold tuning, and watchdog configuration require I²C access.
What thermal protection features are implemented in the PCA9421UKZ?
The PCA9421UKZ integrates two independent thermal functions: a 2-bit programmable warning threshold (75–90 °C in 5 °C steps) and a 3-bit programmable shutdown threshold (95–125 °C in 5 °C steps). Both trigger open-drain INTB assertion. Shutdown halts all regulators; warning allows firmware to initiate derating. These thresholds are stored in non-volatile registers and persist across power cycles.
Is the PCA9421UKZ pin-compatible with other variants in the PCA9421 family?
No - the PCA9421UKZ (WLCSP25) is not pin-compatible with the PCA9421BS (HVQFN24). While both share identical electrical functionality and register maps, their pin counts (25 vs. 24), layouts, and mechanical footprints differ. The WLCSP25 places MODESEL0/MODESEL1 on E4/E3, whereas HVQFN24 locates them on pins 7/8; AGND3 exists only in WLCSP25 (E2). PCB redesign is required for substitution.
PCA9421UKZ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- NXP Semiconductors
- Series:
- -
- Package/Case:
- 25-UFBGA, WLCSP
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Applications:
- Microcontroller, MCU
- Current - Supply:
- 5.5µA
- Voltage - Supply:
- 3.3V ~ 5.5V
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 25-WLCSP (2.09x2.09)
PCA9421UKZ FAQ
1.How can I place an order for PCA9421UKZ through Aetrix?
Please submit a Request for Quotation (RFQ) for PCA9421UKZ on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for PCA9421UKZ reliable?
The price and inventory of PCA9421UKZ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for PCA9421UKZ is usually 5 days.
3.What payment methods are accepted for PCA9421UKZ?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for PCA9421UKZ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for PCA9421UKZ?
PCA9421UKZ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your PCA9421UKZ order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for PCA9421UKZ?
For technical support, including PCA9421UKZ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your PCA9421UKZ requirements.
6.How does Aetrix verify that PCA9421UKZ is sourced from the original manufacturer or authorized distributors?
All PCA9421UKZ products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that PCA9421UKZ meets industry standards.
7.What is the process for return or replacement of PCA9421UKZ?
All PCA9421UKZ units undergo pre-shipment inspection (PSI). If there is an issue with PCA9421UKZ, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The PCA9421UKZ part is unused and in its original packaging.
Return procedure for PCA9421UKZ:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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