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Renesas ISL85402IRZ-T7A
- Part No.:
- ISL85402IRZ-T7A
- Manufacturer:
- Renesas
- Package:
- 20-VFQFN Exposed Pad
- Datasheet:
-
ISL85402IRZ-T7A.pdf
- Description:
- IC REG BUCK BOOST ADJ 2.5A 20QFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,683
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Product details
Overview
ISL85402IRZ-T7A from Renesas (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, operates from –40°C to +105°C, and features ±1% voltage regulation accuracy for embedded power supplies.
For engineers reviewing the ISL85402IRZ-T7A datasheet, ISL85402IRZ-T7A pinout, ISL85402IRZ-T7A application, or ISL85402IRZ-T7A equivalent, key selection criteria include its programmable 200kHz–2.2MHz switching frequency, PFM mode quiescent current as low as 180µA (with AUXVCC tied to VOUT), hiccup-mode overcurrent protection, and flexible topology support across industrial and battery-powered systems.
Technical Context
The ISL85402IRZ-T7A 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 architecture-main bias LDO (VIN-referenced) and auxiliary LDO (AUXVCC-referenced)-enables automatic switchover to reduce power loss during steady-state operation.
Topology flexibility is achieved via configurable MODE, EXT_BOOST, and LGATE pins: MODE selects forced PWM or PFM; EXT_BOOST enables boost-buck mode when >200mV at startup; LGATE drives external low-side MOSFETs in synchronous buck or boost stages. The IC supports prebiased start-up and soft-start via external capacitor on SS pin charged by internal 5µA current source.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3V to 36V (buck mode); extends below 2.5V in boost-buck configuration |
| Continuous Output Current | 2.5A at 5V VOUT, 8–36V VIN, 500kHz, +105°C ambient, still air |
| Switching Frequency | Programmable 200kHz–2.2MHz; fixed 500kHz when FS pin open/GND/VCC |
| Voltage Regulation Accuracy | ±1% over temperature and line/load, referenced to 0.8V internal bandgap |
| Quiescent Input Current | 180µA in PFM mode with AUXVCC connected to VOUT; 300µA in PFM no-load otherwise |
| Overcurrent Protection | Programmable default 3.6A cycle-by-cycle limit; hiccup mode activates at 115% of limit |
| Package | 20-lead 4mm × 4mm QFN with exposed thermal pad (RoHS-compliant, Pb-free) |
Pinout & Package
ISL85402IRZ-T7A is housed in a 20-lead 4×4 mm QFN package with exposed thermal pad (PAD, Pin 21), optimized for thermal dissipation in high-current DC/DC applications. Pin numbering follows standard top-view layout with EN (1), FS (2), SS (3), FB (4), COMP (5), ILIMIT (6), MODE (7), PGOOD (8), PHASE (9–10), EXT_BOOST (11), SYNC (12), LGATE (13), PGND (14), BOOT (15), VIN (16–17), SGND (18), VCC (19), AUXVCC (20).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| EN (1) | Enable control input | Pulled high or floating to enable; pulled low to disable IC (1.8–3µA shutdown current) |
| FB (4) | Feedback node | Inverting input of error amplifier; sets output voltage via resistor divider to 0.8V reference |
| ILIMIT (6) | Current limit programming | Resistor-to-GND sets threshold; default 3.6A when open/VCC/GND |
| MODE (7) | Operation mode select | GND = forced PWM; floating/VCC = PFM; resistor-to-GND programs PWM/PFM boundary current |
| PHASE (9,10) | High-side MOSFET source connection | Connects to inductor node; also serves as source terminal for integrated 125mΩ high-side N-MOSFET |
| LGATE (13) | Low-side gate driver output | Drives external low-side MOSFET in synchronous buck; disabled in non-synchronous mode by tying to VCC |
| EXT_BOOST (11) | Boost mode enable & monitoring | >200mV at POR enables boost-buck; used to monitor boost input/output voltage via resistor divider |
| AUXVCC (20) | Auxiliary LDO input / boost OVP sense | In buck mode: powers auxiliary LDO for lower-loss VCC bias; in boost mode: detects boost output overvoltage |
Key Features
| Feature | Design Value |
|---|---|
| Integrated high-side MOSFET | 125mΩ rDS(ON) reduces conduction loss and eliminates external high-side switch |
| Topology flexibility | Supports synchronous buck, non-synchronous buck (diode-based), and two-stage boost-buck for ultra-low VIN operation |
| Efficiency-optimized biasing | Automatic AUXVCC-to-VOUT switchover reduces LDO dropout loss, improving light-load efficiency at high VIN |
| Robust fault protection | Combined cycle-by-cycle current limiting, frequency foldback, hiccup mode, overvoltage, and overtemperature protection |
| Prebiased start-up capability | Enables reliable turn-on into precharged output rails without output voltage reversal or overshoot |
Applications
| Industrial 24V Bus Power | Battery-Powered IoT Sensors |
|---|---|
|
Use Scenario: Converting 24V rail to 3.3V/5V for PLC I/O modules, motor drivers, and fieldbus interfaces under wide load and temperature variation. IC Role / Device Role / Timing Role: Primary synchronous buck regulator with integrated high-side FET and programmable frequency for EMI control. Use Value: Delivers 2.5A continuous output with ±1% regulation accuracy and hiccup-mode protection against intermittent shorts in harsh factory environments. |
Use Scenario: Powering ultra-low-power microcontrollers, BLE radios, and environmental sensors from single-cell Li-ion (3.0–4.2V) or multi-cell alkaline batteries. IC Role / Device Role / Timing Role: Boost-buck converter enabling stable 3.3V output even as battery voltage drops below 2.5V. Use Value: PFM mode draws only 180µA quiescent current (with AUXVCC→VOUT), extending battery life while maintaining regulated output down to end-of-discharge. |
| Point-of-Load for Embedded Processors | Automotive Body Control Modules |
|
Use Scenario: Providing clean, tightly regulated 1.2V/1.8V/3.3V rails for FPGA, DSP, or ARM SoC cores and I/O banks on compact PCBs. IC Role / Device Role / Timing Role: High-efficiency synchronous buck controller with soft-start and prebiased start-up for safe power sequencing. Use Value: Programmable 200kHz–2.2MHz switching allows optimization for size (high-freq) or efficiency (low-freq), while ±1% accuracy ensures processor stability. |
Use Scenario: Regulating 12V vehicle battery to 5V for infotainment peripherals, LED lighting controllers, and CAN transceivers in temperature-cycled cabins. IC Role / Device Role / Timing Role: Robust buck regulator with –40°C to +105°C operation, overvoltage/overtemperature protection, and 36V absolute max input rating. Use Value: Withstands load dump transients up to 44V (absolute max), and hiccup-mode OCP prevents thermal runaway during connector short circuits. |
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-T7A | Higher 4A continuous output rating; identical pinout, package, and feature set | Better suited for higher-current loads (>2.5A) without redesign; same footprint and control interface | Select ISL85403IRZ-T7A when output current demand exceeds 2.5A or future-proofing headroom is required |
| MP2451DT-LF-Z | 3A rated, 36V max input, but lacks boost-buck topology support and AUXVCC switchover | Lower BOM cost for basic buck-only designs; no EXT_BOOST or AUXVCC functionality | Choose MP2451DT-LF-Z only for cost-sensitive, single-topology applications where boost-buck and ultra-low IQ are not needed |
Compared with ISL85402IRZ-T7A, ISL85403IRZ-T7A offers higher current capacity in identical packaging, while MP2451DT-LF-Z provides simpler, lower-cost buck regulation without topology flexibility or advanced biasing-making ISL85402IRZ-T7A optimal for mixed-input-voltage, space-constrained, and efficiency-critical designs.
Availability
ISL85402IRZ-T7A is available at Aetrix Electronics and suitable for industrial 24V bus power, battery-powered IoT sensors, and point-of-load embedded processor supplies requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.
Supply support for ISL85402IRZ-T7A 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 Corporation 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-integration DC/DC controller family designed for industrial, automotive, and communications power systems requiring wide input range, topology flexibility, and robust protection-especially where board space and thermal performance are critical.
FAQ
What is the maximum continuous output current of the ISL85402IRZ-T7A?
The ISL85402IRZ-T7A delivers 2.5A continuous output current under defined conditions: 5V output, 8–36V input, 500kHz switching, +105°C ambient, and still-air convection cooling. Actual current depends on thermal design, layout, and operating conditions-die temperature must remain ≤+125°C. The datasheet specifies this rating on page 1, and the current limit is programmable up to 4.2A via ILIMIT pin.
Does the ISL85402IRZ-T7A support boost-buck topology, and how is it configured?
Yes, the ISL85402IRZ-T7A supports boost-buck operation using its EXT_BOOST pin. At power-on reset, if EXT_BOOST voltage exceeds 200mV, the IC latches into boost mode and uses LGATE to drive an external boost switch. The boost stage feeds a second buck stage controlled by the same IC. Configuration requires a resistor divider on EXT_BOOST to set input UV/OV thresholds, as detailed in "Typical Application Schematic III" on page 5 of FN7640.
How does the AUXVCC switchover function improve efficiency in the ISL85402IRZ-T7A?
The ISL85402IRZ-T7A uses AUXVCC switchover to replace the main VIN-referenced LDO with a lower-dropout auxiliary LDO powered from the regulated output. When VOUT rises above ~3.1V, the IC switches biasing to AUXVCC, reducing internal LDO power loss-especially beneficial at high input voltages (e.g., 24V→3.3V). This improves light-load efficiency and lowers die temperature, as confirmed in Figure 10 and Functional Description section on page 13.
What protection features does the ISL85402IRZ-T7A include, and how do they operate?
The ISL85402IRZ-T7A integrates cycle-by-cycle current limiting with frequency foldback, hiccup-mode overcurrent (triggered at 115% of programmed limit), overvoltage protection (latching at 120% VREF), undervoltage lockout, and overtemperature shutdown (trip at +155°C, recover at +140°C). These protections are hardware-based and operate independently of external components-no firmware or external supervision required for safe operation under fault conditions.
Can the ISL85402IRZ-T7A start up into a prebiased output, and what design considerations apply?
Yes, the ISL85402IRZ-T7A supports prebiased start-up, allowing safe turn-on when the output capacitor is already charged. During prebias, the high-side MOSFET remains off until the soft-start ramp reaches the feedback reference, preventing reverse current flow or output collapse. Layout must minimize PHASE node parasitics, and the SS capacitor value should follow Equation 1 (page 13) to ensure proper ramp timing-verified in Figure 14 of the datasheet.
ISL85402IRZ-T7A 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-T7A FAQ
1.How can I place an order for ISL85402IRZ-T7A through Aetrix?
Please submit a Request for Quotation (RFQ) for ISL85402IRZ-T7A 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-T7A reliable?
The price and inventory of ISL85402IRZ-T7A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ISL85402IRZ-T7A is usually 5 days.
3.What payment methods are accepted for ISL85402IRZ-T7A?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ISL85402IRZ-T7A transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for ISL85402IRZ-T7A?
ISL85402IRZ-T7A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your ISL85402IRZ-T7A 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-T7A?
For technical support, including ISL85402IRZ-T7A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ISL85402IRZ-T7A requirements.
6.How does Aetrix verify that ISL85402IRZ-T7A is sourced from the original manufacturer or authorized distributors?
All ISL85402IRZ-T7A 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-T7A meets industry standards.
7.What is the process for return or replacement of ISL85402IRZ-T7A?
All ISL85402IRZ-T7A units undergo pre-shipment inspection (PSI). If there is an issue with ISL85402IRZ-T7A, 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-T7A part is unused and in its original packaging.
Return procedure for ISL85402IRZ-T7A:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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