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Renesas ISL85402IRZ-T
- Part No.:
- ISL85402IRZ-T
- Manufacturer:
- Renesas
- Package:
- 20-VFQFN Exposed Pad
- Datasheet:
-
ISL85402IRZ-T.pdf
- Description:
- IC REG BUCK BOOST ADJ 2.5A 20QFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,713
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Product details
Overview
ISL85402IRZ-T from Renesas Electronics is a synchronous buck controller with integrated 125mΩ high-side MOSFET and low-side gate driver, supporting 3V–36V input in buck mode and expandable to <2.5V via boost-buck topology. It delivers 2.5A continuous output at 5V with 500kHz switching and +105°C ambient, featuring ±1% voltage regulation accuracy, programmable 200kHz–2.2MHz frequency, and hiccup-mode overcurrent protection. It serves as a primary DC-DC regulator in industrial power supplies and embedded processor rails.
For engineers reviewing the ISL85402IRZ-T datasheet, ISL85402IRZ-T pinout, ISL85402IRZ-T application, or ISL85402IRZ-T equivalent, key selection considerations include its dual-mode (PWM/PFM) operation, integrated high-side FET with thermal-limited current capability, flexible boost-buck topology support, AUXVCC switch-over for light-load efficiency, and robust fault protections including cycle-by-cycle current limiting, overvoltage, and overtemperature.
Technical Context
The ISL85402IRZ-T implements peak current mode control with slope compensation for stable loop response and fast transient immunity. Its dual LDO architecture-main bias LDO (VIN-fed) and auxiliary LDO (AUXVCC-fed)-enables automatic switchover post-startup to reduce dropout loss and improve light-load efficiency.
It supports three operational topologies: synchronous buck (LGATE drives external low-side FET), non-synchronous buck (LGATE disabled via VCC tie), and two-stage boost-buck (EXT_BOOST enables boost pre-regulation). Mode selection (PFM/PWM), current limit threshold (ILIMIT), and soft-start timing (SS) are all externally programmable via resistor or capacitor networks.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3V to 36V (buck mode); extends below 2.5V when configured as boost-buck) |
| Output Current | 2.5A continuous at 5V VOUT, 500kHz, +105°C ambient, still air |
| Regulation Accuracy | ±1% over line, load, and temperature - ensures stable I/O and core rail compliance |
| Switching Frequency | Programmable 200kHz–2.2MHz; sync-capable for multi-phase noise reduction |
| Quiescent Current | 180µA (PFM, no load, AUXVCC connected to VOUT) - enables battery-backed standby |
| High-Side rDS(ON) | 125mΩ typical - limits conduction loss and thermal rise at full load |
| Protection Features | Cycle-by-cycle current limiting with frequency foldback + hiccup mode - sustains operation under sustained overload |
Pinout & Package
ISL85402IRZ-T is housed in a thermally enhanced 20-lead 4mm × 4mm QFN package with exposed thermal pad (L20.4x4C). The package supports high-power density PCB layouts and requires direct connection of the bottom pad to a large ground copper plane for effective heat dissipation (θJC = 3.5°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| EN (Pin 1) | Enable control input | Active-high logic; IC disabled when pulled ≤0.8V - enables system-level power sequencing |
| FS (Pin 2) | Oscillator frequency set | Resistor-to-GND sets frequency from 200kHz–2.2MHz; open/VCC/GND forces 500kHz |
| SS (Pin 3) | Soft-start ramp control | Capacitor-to-GND sets startup time via 5µA internal current source - prevents inrush and enables tracking |
| FB (Pin 4) | Voltage feedback node | Inverting input of error amplifier referenced to 0.8V - sets output voltage via resistor divider |
| COMP (Pin 5) | Error amplifier output | Compensation node for loop stability - RC network between COMP and FB sets pole/zero placement |
| ILIMIT (Pin 6) | Current limit programming | Resistor-to-GND adjusts cycle-by-cycle OCP threshold from default 3.6A - tailors protection to inductor and layout |
| MODE (Pin 7) | PFM/PWM mode select | Pull to GND = forced PWM; float/VCC = PFM at light load - optimizes efficiency across load range |
| PGOOD (Pin 8) | Power-good status | Open-drain output with 1000-cycle delay - signals valid regulation and enables downstream sequencing |
| PHASE (Pins 9,10) | High-side MOSFET source node | Connects directly to inductor - carries full switching current and defines buck/boost node voltage swing |
| EXT_BOOST (Pin 11) | Boost mode enable & monitor | Detects >200mV to latch into boost-buck; monitors boost output via resistor divider for OVP |
| SYNC (Pin 12) | Frequency synchronization | Accepts external clock or daisy-chains multiple ICs with auto 180° phase shift - reduces EMI peaks |
| LGATE (Pin 13) | Low-side gate driver output | Drives external N-MOSFET in synchronous buck; disabled in non-sync mode by tying to VCC pre-startup |
| PGND (Pin 14) | Power ground return | High-current return path for drivers and PHASE - must connect to low-impedance ground plane |
| BOOT (Pin 15) | High-side gate bias supply | Internal bootstrap circuit generates gate drive voltage - requires 1µF ceramic cap to PHASE |
| VIN (Pins 16,17) | Main input supply | Connects to drain of integrated high-side MOSFET and main LDO input - handles up to 36V operating, 44V abs max |
| SGND (Pin 18) | Signal ground reference | Return for control circuitry only - isolated from PGND to minimize noise coupling into feedback path |
| VCC (Pin 19) | Main LDO output | 4.5V ±0.3V regulated supply for internal circuitry - decoupled with ≥4.7µF ceramic cap |
| AUXVCC (Pin 20) | Auxiliary LDO input/output | Accepts 3V–20V input for switchover; in boost mode, functions as OVP sense pin for boost output |
| Thermal Pad (Pin 21) | Thermal interface | Electrically isolated copper pad - must be soldered to PCB ground plane for θJA = 40°C/W |
Key Features
| Feature | Design Value |
|---|---|
| Integrated high-side MOSFET | 125mΩ rDS(ON) eliminates external high-side switch and simplifies layout while maintaining thermal headroom at 2.5A |
| Three configurable topologies | Supports synchronous buck, non-synchronous buck (diode-based), and boost-buck - extends usable input range down to 2.5V or lower |
| AUXVCC LDO switchover | Reduces internal LDO dropout loss by powering VCC from regulated output post-startup - improves light-load efficiency at high VIN |
| Programmable PFM/PWM boundary | Resistor on MODE pin sets transition current threshold (e.g., 700mA default) - balances efficiency vs. output ripple across load range |
| Hiccup-mode overcurrent protection | Enters extended soft-start (5× duration) upon repeated OCP events - prevents thermal runaway during sustained short-circuit conditions |
Applications
| Industrial 24V Bus Power | Battery-Powered Embedded Systems |
|---|---|
Use Scenario: Regulating unregulated 24V industrial bus to 5V/3.3V for PLC I/O modules and sensor interfaces. IC Role / Device Role / Timing Role: Primary synchronous buck controller with integrated high-side FET and PFM mode for variable load profiles. Use Value: 2.5A output capacity and 3V–36V input range accommodate wide bus tolerances; hiccup OCP ensures reliability in harsh factory environments. | Use Scenario: Powering ARM Cortex-M microcontrollers and peripherals from single-cell Li-ion (3.0–4.2V) or multi-cell alkaline packs. IC Role / Device Role / Timing Role: Boost-buck regulator enabling operation below 2.5V input while delivering stable 3.3V at up to 2.5A. Use Value: 180µA PFM quiescent current extends battery life; AUXVCC switchover minimizes dropout loss during active operation. |
| Point-of-Load (PoL) for FPGA I/O Rails | Automotive Body Control Module (BCM) Supplies |
Use Scenario: Generating clean, tightly regulated 1.2V/1.8V/3.3V rails adjacent to FPGA banks with fast transient demands. IC Role / Device Role / Timing Role: Synchronous buck controller with peak current mode control and ±1% regulation accuracy. Use Value: Fast transient response and programmable 200kHz–2.2MHz frequency allow optimal trade-off between size and EMI in dense PCB layouts. | Use Scenario: Converting 12V vehicle battery (9V–16V range) to 5V for CAN transceivers, EEPROM, and MCU peripherals. IC Role / Device Role / Timing Role: Robust buck regulator with overvoltage, overtemperature, and cycle-by-cycle current limiting. Use Value: 44V absolute max input rating withstands load-dump transients; -40°C to +105°C operation meets AEC-Q100 ambient requirements. |
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-T | Higher 4A output current rating; identical pinout and feature set; recommended replacement per datasheet | Required where >2.5A continuous load or higher thermal margin is needed | Select ISL85403IRZ-T for new designs requiring higher current headroom without layout change |
| MP2451DT-LF-Z | 3A rated, 3.3V–36V input, but lacks boost-buck topology support and AUXVCC switchover | Suitable for standard buck-only applications with simpler BOM and lower cost | Choose MP2451DT-LF-Z when boost-buck functionality and ultra-low quiescent current are not required |
Compared with ISL85402IRZ-T, the ISL85403IRZ-T offers higher current capability in identical packaging for drop-in upgrades, while the MP2451DT-LF-Z provides a cost-optimized alternative for basic buck conversion without advanced features like PFM optimization or multi-topology flexibility.
Availability
ISL85402IRZ-T is available at Aetrix Electronics and suitable for industrial 24V bus power, battery-powered embedded systems, and point-of-load FPGA I/O supplies requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.
Supply support for ISL85402IRZ-T 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 is a global semiconductor leader delivering microcontrollers, analog, power, and SoC solutions for automotive, industrial, infrastructure, and IoT markets.
The ISL85402IRZ-T belongs to Renesas' ISL85xx family of integrated power controllers, designed specifically for high-efficiency, multi-topology DC-DC conversion in space-constrained industrial and embedded applications.
FAQ
What is the maximum continuous output current supported by the ISL85402IRZ-T?
The ISL85402IRZ-T supports 2.5A continuous output current under defined conditions: 5V output, input voltage range of 8V–36V, 500kHz switching frequency, and +105°C ambient temperature with still air cooling. Actual maximum current depends on die temperature staying below +125°C, which varies with board layout, input/output voltage, duty cycle, and airflow. Refer to page 14 of the FN7640 datasheet for thermal derating guidance specific to the ISL85402IRZ-T.
Does the ISL85402IRZ-T support both buck and boost configurations?
The ISL85402IRZ-T does not operate as a standalone boost converter. However, it supports a two-stage boost-buck topology where an external boost stage feeds a buck stage controlled by the same ISL85402IRZ-T - enabling operation with input voltages as low as 2.5V or lower. This is enabled via the EXT_BOOST pin, which detects and latches into boost-buck mode when voltage exceeds 200mV at power-on reset. The ISL85402IRZ-T itself remains a buck controller in this configuration.
How does the AUXVCC switchover function improve efficiency in the ISL85402IRZ-T?
The ISL85402IRZ-T uses AUXVCC switchover to replace the main VIN-fed LDO with an auxiliary LDO powered from the regulated output voltage after startup. Since AUXVCC voltage (e.g., 5V) is lower than VIN (e.g., 24V), the LDO dropout voltage and associated power loss are reduced - improving light-load efficiency significantly, especially in high-input-voltage applications. Switchover occurs when AUXVCC rises above 3.1V and reverts to the main LDO if AUXVCC falls below 2.87V or during OV/UV faults.
What protection features are implemented in the ISL85402IRZ-T?
The ISL85402IRZ-T integrates cycle-by-cycle current limiting with frequency foldback, hiccup-mode overcurrent protection, overvoltage protection (latching and non-latching modes), overtemperature shutdown (trip at +155°C, recovery at +140°C), and power-good monitoring with 2ms delay. These protections are hardware-based and operate independently of external components, ensuring reliable operation under fault conditions such as short circuits, overloads, or thermal stress without requiring firmware intervention.
Is the ISL85402IRZ-T pin-compatible with any newer Renesas parts?
Yes - the ISL85402IRZ-T is pin-compatible with the ISL85403IRZ-T, which is explicitly designated in the FN7640 datasheet as the "RECOMMENDED REPLACEMENT PART." The ISL85403IRZ-T shares identical pinout, package (20 Ld 4x4 QFN), and feature set, but supports 4A continuous output current instead of 2.5A. No PCB changes are required for migration, making it a direct upgrade path for designs needing higher current capability.
ISL85402IRZ-T 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-T FAQ
1.How can I place an order for ISL85402IRZ-T through Aetrix?
Please submit a Request for Quotation (RFQ) for ISL85402IRZ-T 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-T reliable?
The price and inventory of ISL85402IRZ-T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ISL85402IRZ-T is usually 5 days.
3.What payment methods are accepted for ISL85402IRZ-T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ISL85402IRZ-T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for ISL85402IRZ-T?
ISL85402IRZ-T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your ISL85402IRZ-T 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-T?
For technical support, including ISL85402IRZ-T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ISL85402IRZ-T requirements.
6.How does Aetrix verify that ISL85402IRZ-T is sourced from the original manufacturer or authorized distributors?
All ISL85402IRZ-T 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-T meets industry standards.
7.What is the process for return or replacement of ISL85402IRZ-T?
All ISL85402IRZ-T units undergo pre-shipment inspection (PSI). If there is an issue with ISL85402IRZ-T, 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-T part is unused and in its original packaging.
Return procedure for ISL85402IRZ-T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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