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Renesas ISL85402IRZ-TK
- Part No.:
- ISL85402IRZ-TK
- Manufacturer:
- Renesas
- Package:
- 20-VFQFN Exposed Pad
- Datasheet:
-
ISL85402IRZ-TK.pdf
- Description:
- IC REG BUCK BOOST ADJ 2.5A 20QFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,510
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Product details
Overview
ISL85402IRZ-TK from Renesas Electronics (formerly Intersil) is a synchronous buck controller with integrated 125mΩ high-side MOSFET and low-side gate driver, supporting buck, non-synchronous buck, and two-stage boost-buck topologies. It delivers 2.5A continuous output at 5V with 8–36V input in buck mode, operates from –40°C to +105°C, and features ±1% output voltage regulation accuracy for embedded power supply applications.
For engineers reviewing the ISL85402IRZ-TK datasheet, ISL85402IRZ-TK pinout, ISL85402IRZ-TK application, or ISL85402IRZ-TK equivalent, key selection considerations include its programmable 200kHz–2.2MHz switching frequency, dual LDO architecture (MAIN/AUXVCC switchover), hiccup-mode overcurrent protection, and flexible PFM/PWM mode selection for light-load efficiency optimization.
Technical Context
The ISL85402IRZ-TK implements peak current mode control with cycle-by-cycle current limiting and frequency foldback under overload, plus hiccup-mode recovery for sustained short-circuit conditions. Its dual LDO system enables AUXVCC switchover to reduce internal power dissipation after startup - critical for high-input-voltage, light-load operation.
It supports three distinct operational topologies: synchronous buck (LGATE drives external low-side FET), non-synchronous buck (LGATE disabled via VCC tie), and boost-buck (EXT_BOOST pin configures boost pre-regulator stage enabling input as low as 2.5V). Mode selection is hardware-configurable via MODE and EXT_BOOST pins without firmware.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3V to 36V (buck mode); extends below 2.5V in boost-buck configuration via EXT_BOOST pin detection |
| Continuous Output Current | 2.5A at 5V VOUT, 8–36V VIN, 500kHz, +105°C ambient - validated under still-air thermal conditions |
| Switching Frequency | Programmable 200kHz–2.2MHz via FS pin resistor; supports synchronization across multiple ICs with 180° phase shift |
| Voltage Regulation Accuracy | ±1% over temperature and line/load - ensures stable 0.8V reference tracking for precise output setting |
| Quiescent Input Current | 180µA in PFM mode with AUXVCC connected to VOUT - enables ultra-low-power standby in battery systems |
| Overcurrent Protection | Dual-threshold: 3.6A cycle-by-cycle limit (default ILIMIT pin config) + 115% hiccup threshold for fault recovery |
| Package | 20-lead 4×4mm QFN with exposed thermal pad - optimized for thermal performance in compact PCB layouts |
Pinout & Package
ISL85402IRZ-TK uses a 20-lead 4×4mm QFN package (Pb-free, RoHS-compliant) with bottom thermal pad (PAD, Pin 21) requiring direct connection to PCB ground plane for thermal management.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| EN (1) | Enable control input | Active-high logic: IC enabled when floating or >2V; disabled when pulled <0.8V - supports system-level power sequencing |
| FS (2) | Oscillator frequency set | Resistor-to-GND sets frequency (200kHz–2.2MHz); open/VCC/GND forces 500kHz - enables precise EMI tuning |
| SS (3) | Soft-start ramp control | External capacitor charged by 5µA current source - controls startup dV/dt and prevents inrush; also used in hiccup recovery |
| FB (4) | Feedback error amplifier input | Inverting input referenced to 0.8V internal bandgap - sets output voltage via resistor divider; monitored for OVP/UVP |
| COMP (5) | Error amplifier output | Compensated loop signal driving PWM comparator - connects to FB via RC network for stability |
| ILIMIT (6) | Current limit threshold adjust | Resistor-to-GND programs cycle-by-cycle limit (default 3.6A); enables design-specific OCP tailoring |
| MODE (7) | PFM/PWM mode select | Pull to GND = forced PWM; float/VCC = PFM at <700mA peak inductor current - configurable boundary via resistor |
| PGOOD (8) | Power-good status flag | Open-drain output with 1000-cycle delay on power-up - signals valid regulation (90–110% of target) and faults |
| PHASE (9,10) | High-side MOSFET source node | Connects to inductor - carries full switching current; tied internally to source of integrated 125mΩ N-channel FET |
| EXT_BOOST (11) | Boost mode enable & monitoring | Detects >200mV at POR to latch into boost-buck mode; monitors boost output via resistor divider for OVP |
| SYNC (12) | Frequency synchronization input | Accepts external clock (10% higher than local freq); enables multi-phase interleaving with automatic 180° phase shift |
| LGATE (13) | Low-side gate driver output | Drives external N-FET in sync-buck; disabled in non-sync mode (tie to VCC pre-startup); drives boost switch in boost-buck |
| PGND (14) | Power ground return | High-current return path for drivers and PHASE - must connect to large copper pour to minimize noise and losses |
| BOOT (15) | High-side gate drive bias | Bootstrap node generating ~6V above PHASE - integrated charge pump eliminates need for external boot diode |
| VIN (16,17) | Main power input | Connects to drain of internal high-side MOSFET and MAIN LDO input - rated 3–36V; handles 44V abs max transient |
| SGND (18) | Analog/monitor ground | Quiet reference for FB, COMP, MODE, etc. - separate from PGND to avoid control-loop coupling |
| VCC (19) | Main LDO output | 4.5V ±0.3V regulated supply for internal circuitry - sourced from VIN or AUXVCC via switchover logic |
| AUXVCC (20) | Auxiliary LDO input / boost OVP sense | In buck mode: input for auxiliary LDO (3–20V); in boost mode: senses boost output via resistor divider for OVP |
| PAD (21) | Thermal pad | Non-electrical exposed copper - must be soldered to PCB ground plane for θJC = 3.5°C/W thermal performance |
Key Features
| Feature | Design Value |
|---|---|
| Integrated high-side MOSFET | 125mΩ rDS(ON) reduces conduction loss and eliminates external high-side driver complexity |
| Two-stage boost-buck topology support | Enables operation down to 2.5V input using EXT_BOOST pin detection - extends usability in wide-input battery systems |
| AUXVCC switchover LDO | Reduces internal power dissipation by switching bias from MAIN LDO (VIN-derived) to AUXVCC (VOUT-derived) post-startup |
| Hiccup-mode overcurrent protection | Enters extended soft-start (5× duration) upon second-tier overcurrent detection - prevents thermal runaway during sustained shorts |
| Programmable PFM/PWM transition | Boundary current threshold adjustable via MODE pin resistor - optimizes efficiency across load range without firmware |
| Robust fault coverage | Includes overvoltage (latching/non-latching), undervoltage, overtemperature (155°C trip), and PGOOD monitoring |
Applications
| Industrial PLC I/O Power | Automotive Body Control Module |
|---|---|
|
Use Scenario: Powering isolated digital I/O channels in programmable logic controllers with 24V bus input and variable load profiles. IC Role / Device Role / Timing Role: Synchronous buck regulator delivering stable 3.3V/5V from 24V rail; manages dynamic load steps up to 2A while maintaining tight regulation. Use Value: ±1% regulation accuracy and hiccup-mode OCP ensure reliable channel operation during field-wiring faults or shorted outputs. |
Use Scenario: Supplying microcontroller core and peripheral rails in automotive body control units powered by 12V battery with cold-crank dips. IC Role / Device Role / Timing Role: Non-synchronous buck converter (diode-based) operating from 5.5V–16V input; leverages PFM mode for <180µA quiescent current during sleep. Use Value: AUXVCC switchover reduces dropout loss at high VIN, improving efficiency during engine-run conditions; EN pin enables controlled wake-up sequencing. |
| Portable Medical Instrumentation | Point-of-Load for FPGA I/O Banks |
|
Use Scenario: Battery-powered handheld diagnostic devices requiring long runtime and clean 1.8V/3.3V supplies from Li-ion (3.0–4.2V) or 2-cell alkaline (2.5–3.6V). IC Role / Device Role / Timing Role: Boost-buck converter: boost stage lifts input to ≥5V, followed by buck stage regulating precise output - enabled by EXT_BOOST pin logic. Use Value: Seamless transition between battery chemistries and states of charge without manual reconfiguration; PFM mode extends battery life during idle periods. |
Use Scenario: Providing tightly regulated 1.2V or 1.8V to FPGA I/O banks in industrial edge computing modules with 12V or 24V backplane input. IC Role / Device Role / Timing Role: Synchronous buck regulator with forced PWM mode and 500kHz switching - minimizes output ripple and improves transient response to I/O switching noise. Use Value: Integrated 125mΩ high-side FET and LGATE driver eliminate external components; SS pin allows coordinated startup with FPGA configuration sequence. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous buck controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| ISL85403IRZ-TK | Higher 4A continuous output rating; identical pinout, package, and feature set - direct drop-in replacement with increased current headroom | Required where >2.5A sustained load or higher thermal margin is needed; same footprint and layout compatibility | Select ISL85403IRZ-TK when future-proofing for higher current or derating requirements; no schematic or layout changes needed |
| MP2451DT-LF-Z | 3A monolithic buck converter (no external LGATE); fixed 500kHz frequency; lacks boost-buck topology, AUXVCC switchover, and SYNC capability | Suitable for cost-sensitive, single-topology 12V-to-5V/3.3V conversion where advanced features are unnecessary | Choose MP2451DT-LF-Z only for simplified designs without multi-topology needs or stringent light-load efficiency targets |
Compared with ISL85402IRZ-TK, the ISL85403IRZ-TK offers higher current capacity in identical form factor, while the MP2451DT-LF-Z trades flexibility and efficiency features for lower BOM count and cost - making ISL85402IRZ-TK optimal for adaptable, thermally constrained, or battery-sensitive designs.
Availability
ISL85402IRZ-TK is available at Aetrix Electronics and suitable for industrial PLC I/O power, automotive body control modules, portable medical instrumentation, and FPGA point-of-load applications requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.
Supply support for ISL85402IRZ-TK 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
Renesas Electronics acquired Intersil in 2017 and maintains full technical and manufacturing continuity for the ISL85402 product line. Renesas is a global semiconductor leader focused on embedded solutions, analog power, and connectivity.
The ISL85402 belongs to Renesas' high-voltage synchronous buck controller family, designed specifically for robust, flexible DC-DC conversion in industrial, automotive, and medical equipment where wide input range, topology adaptability, and fault resilience are critical.
FAQ
What is the maximum continuous output current of the ISL85402IRZ-TK?
The ISL85402IRZ-TK delivers 2.5A continuous output current under defined conditions: 5V output, 8–36V input, 500kHz switching frequency, and +105°C ambient temperature with still air. Actual current depends on thermal design, board layout, and operating conditions - die temperature must not exceed +125°C. The datasheet specifies this rating on page 1.
Does the ISL85402IRZ-TK support boost-buck topology, and how is it configured?
Yes, the ISL85402IRZ-TK supports two-stage boost-buck operation. Configuration is hardware-based: at power-on reset, the IC samples EXT_BOOST pin voltage - if >200mV, it latches into boost-buck mode. In this mode, LGATE drives the boost switch synchronously with the buck high-side, and EXT_BOOST monitors boost output for overvoltage protection. Details are in Figure 5 and page 14 of the datasheet.
How does the AUXVCC switchover function improve efficiency in the ISL85402IRZ-TK?
The ISL85402IRZ-TK uses AUXVCC switchover to reduce internal power loss: after startup, when VOUT rises above 3.1V, the IC disables the MAIN LDO (biased from VIN) and activates the AUXILIARY LDO (biased from VOUT). Since VOUT < VIN, the LDO dropout voltage-and thus power dissipation-is significantly reduced, especially at high input voltages and light loads. This feature is active only in buck mode.
What overcurrent protection mechanisms does the ISL85402IRZ-TK implement?
The ISL85402IRZ-TK implements three-tier overcurrent protection: (1) cycle-by-cycle peak current limiting at default 3.6A (adjustable via ILIMIT pin), (2) frequency foldback during sustained overcurrent to reduce power dissipation, and (3) hiccup mode triggered at 115% of the primary limit - which forces a 5× extended soft-start cycle before retry. This ensures safe operation under short-circuit or overload conditions without thermal runaway.
Can the ISL85402IRZ-TK operate in forced PWM mode, and how is it enabled?
Yes, the ISL85402IRZ-TK supports forced PWM mode for consistent switching frequency and minimized output ripple. To enable it, pull the MODE pin (Pin 7) to GND. In this mode, the IC ignores load-dependent PFM transitions and maintains constant-frequency operation regardless of output current - ideal for noise-sensitive applications or when EMI filtering requires predictable harmonics.
ISL85402IRZ-TK Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Renesas
- Series:
- -
- Package/Case:
- 20-VFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Function:
- Step-Up, Step-Down, Step-Up/Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck, Boost, Buck-Boost
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 3V
- Voltage - Input (Max):
- 36V
- Voltage - Output (Min/Fixed):
- 0.8V
- Voltage - Output (Max):
- 34V
- Current - Output:
- 2.5A
- Frequency - Switching:
- 200kHz ~ 2.2MHz
- Synchronous Rectifier:
- Both
- Operating Temperature:
- -40°C ~ 105°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-QFN (4x4)
ISL85402IRZ-TK FAQ
1.How can I place an order for ISL85402IRZ-TK through Aetrix?
Please submit a Request for Quotation (RFQ) for ISL85402IRZ-TK 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 ISL85402IRZ-TK reliable?
The price and inventory of ISL85402IRZ-TK are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ISL85402IRZ-TK is usually 5 days.
3.What payment methods are accepted for ISL85402IRZ-TK?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ISL85402IRZ-TK transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for ISL85402IRZ-TK?
ISL85402IRZ-TK orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your ISL85402IRZ-TK 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 ISL85402IRZ-TK?
For technical support, including ISL85402IRZ-TK datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ISL85402IRZ-TK requirements.
6.How does Aetrix verify that ISL85402IRZ-TK is sourced from the original manufacturer or authorized distributors?
All ISL85402IRZ-TK 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 ISL85402IRZ-TK meets industry standards.
7.What is the process for return or replacement of ISL85402IRZ-TK?
All ISL85402IRZ-TK units undergo pre-shipment inspection (PSI). If there is an issue with ISL85402IRZ-TK, 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 ISL85402IRZ-TK part is unused and in its original packaging.
Return procedure for ISL85402IRZ-TK:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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