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Renesas ISL85403FRZ-T
- Part No.:
- ISL85403FRZ-T
- Manufacturer:
- Renesas
- Package:
- 20-VFQFN Exposed Pad
- Datasheet:
-
ISL85403FRZ-T.pdf
- Description:
- IC REG BUCK BOOST ADJ 2.5A 20QFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,542
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Product details
Overview
ISL85403FRZ-T from Renesas Electronics is a 40V, 2.5A synchronous buck/boost-buck controller with integrated high-side MOSFET (rDS(ON) = 140 mΩ), programmable 200 kHz–2.2 MHz switching frequency, ±1% output voltage regulation accuracy, and dual-mode operation (Forced PWM or PFM with 180 µA quiescent current when AUXVCC tied to VOUT). It enables robust point-of-load power for industrial battery-powered systems requiring VIN dropout resilience down to 2.5V.
For engineers reviewing the ISL85403FRZ-T datasheet, ISL85403FRZ-T pinout, ISL85403FRZ-T application, or ISL85403FRZ-T equivalent, key selection criteria include its 20-lead QFN package thermal performance (θJA = 40°C/W), cycle-by-cycle overcurrent protection with hiccup mode, dual LDO architecture (main + auxiliary), and flexible topology support-synchronous buck, non-synchronous buck, two-stage boost-buck, and non-inverting buck-boost.
Technical Context
The ISL85403FRZ-T implements peak current mode control with temperature-compensated current sensing and frequency foldback during overload. Its dual LDO system (main VCC and AUXVCC) enables switchover at 3.1 V rising / 2.87 V falling thresholds to reduce internal power dissipation in regulated output configurations.
Topology flexibility stems from independent control of high-side (integrated N-MOSFET) and low-side (LGATE driver) stages: LGATE can drive an external synchronous rectifier, remain disabled for diode-based buck, or operate in phase with BOOT to enable boost-buck preregulation. EXT_BOOST and AUXVCC pins provide dedicated voltage monitoring for boost-mode entry and overvoltage shutdown.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3V–40V (buck); extends to 2.5V with boost-buck topology-enables operation during brownout or battery sag. |
| Output Current Rating | 2.5A continuous load capability-supports mid-power PoL rails for processors, FPGAs, and I/O banks. |
| Switching Frequency | 200 kHz–2.2 MHz (programmable via RT resistor); 500 kHz default-balances efficiency, size, and EMI in compact layouts. |
| Voltage Regulation Accuracy | ±1% over line/load/temperature-ensures stable 0.8V reference tracking for precision 3.3V/5V/12V outputs. |
| Quiescent Current | 180 µA (PFM, no load, AUXVCC → VOUT)-extends battery runtime in always-on sensor or backup systems. |
| Overcurrent Protection | Programmable 3.6A default cycle-by-cycle limit with hiccup mode-prevents thermal runaway under sustained short-circuit. |
| Package | 20-lead 4×4 mm QFN with exposed thermal pad-supports ≤125°C junction temp with standard PCB copper pour. |
Pinout & Package
ISL85403FRZ-T is housed in a RoHS-compliant 20-lead 4×4 mm QFN package (PKG DWG # L20.4x4C) with an exposed thermal pad (PAD) that must be soldered to a large PCB ground plane for optimal thermal performance (θJA = 40°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| EN (1) | Enable control input | Active-high logic; pull LOW to disable IC and reduce supply current to ≤4.5 µA-enables system-level power sequencing. |
| FS (2) | Frequency select | Set fixed 500 kHz or program 200 kHz–2.2 MHz via RT-to-GND resistor-allows EMI tuning and inductor size optimization. |
| SS (3) | Soft-start timing | Connect external capacitor to GND; internal 5 µA current source sets ramp time-prevents inrush current and output overshoot. |
| FB (4) | Feedback node | Inverting input of error amplifier; monitors output via resistor divider referenced to 0.8V-defines regulated output voltage (VOUT = 0.8V × (1+R1/R2)). |
| COMP (5) | Error amplifier output | Drives compensation network between COMP and FB-stabilizes loop response for varied output capacitors and loads. |
| ILIMIT (6) | Current limit programming | Resistor-to-GND sets threshold from default 3.6A-configures OCP for specific inductor saturation or MOSFET SOA. |
| MODE (7) | PFM/PWM mode control | Pull to GND for Forced PWM; float/VCC for PFM-selects light-load efficiency strategy based on system duty cycle. |
| PGOOD (8) | Power-good indicator | Open-drain output with 128-cycle delay-signals valid regulation to host MCU or sequencer after soft-start completion. |
| PHASE (9,10) | High-side switch node | Connects to inductor; sourced by integrated 140 mΩ N-MOSFET-carries full switching current and defines buck/boost polarity. |
| EXT_BOOST (11) | Boost mode enable/sense | Detects input voltage via resistor divider; >200 mV triggers boost-buck operation-enables VIN < VOUT regulation without external circuitry. |
| SYNC (12) | External clock synchronization | Accepts square-wave input (10% higher freq than local oscillator); enables multi-phase interleaving or EMI reduction. |
| LGATE (13) | Low-side gate driver | Drives external N-MOSFET in sync buck or boost switch in boost-buck-eliminates need for separate gate driver IC. |
| PGND (14) | Power ground return | High-current return path for MOSFETs and drivers-must connect to thick copper plane to minimize noise coupling into SGND. |
| BOOT (15) | High-side gate bias | Internal bootstrap circuit charges 1 µF cap to PHASE-provides gate drive above VIN for integrated high-side MOSFET. |
| VIN (16,17) | Main input supply | Drain connection of integrated high-side MOSFET and input to main LDO-accepts 3V–40V with 44V absolute max rating. |
| SGND (18) | Signal ground reference | Analog/digital reference for FB, COMP, MODE-requires separate quiet ground trace to avoid switching noise corruption. |
| VCC (19) | Main LDO output | 4.5V ±0.3V regulated supply for internal circuitry-requires ≥4.7 µF ceramic decoupling for stability under transient load. |
| AUXVCC (20) | Auxiliary LDO input | Accepts 4.5V–20V input; enables switchover from main LDO to reduce power loss when VOUT ≥ 4.5V. |
| PAD | Thermal pad | Electrically isolated metal pad-must be soldered to PCB ground plane to achieve θJC = 3.5°C/W and sustain 2.5A continuous operation. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated high-side MOSFET | rDS(ON) = 140 mΩ @ +25°C reduces conduction loss and eliminates external high-side driver complexity. |
| Two-stage boost-buck topology | Extends functional input range to 2.5V while maintaining regulated output-critical for Li-ion battery systems with deep discharge. |
| Programmable PFM/PWM boundary | Adjustable transition current (default 700 mA) optimizes efficiency across wide load ranges without sacrificing transient response. |
| Dual LDO architecture | Main + auxiliary LDOs with 0.2 V hysteresis enable seamless switchover-lowers internal power dissipation by >30% in VOUT ≥ 5V designs. |
| Robust fault protection | Cycle-by-cycle OCP with frequency foldback + hiccup mode + OV/UV/OTP ensures reliable operation in harsh industrial environments. |
| Flexible synchronization | SYNC pin supports master-slave interleaving or external clock locking-reduces input ripple and EMI in multi-rail systems. |
Applications
| Industrial Battery-Powered Sensors | Embedded Processor Core Rails |
|---|---|
|
Use Scenario: Remote environmental monitoring node powered by 2-cell Li-ion (6–8.4V nominal), operating down to 5V under load. IC Role / Device Role / Timing Role: Primary buck regulator delivering 3.3V/2.5A to MCU, RF transceiver, and analog front-end. Use Value: PFM mode maintains 85%+ efficiency at 10 mA sleep current; boost-buck extends runtime by 18% below 5.5V input. |
Use Scenario: FPGA I/O bank supply requiring tight regulation (±1%) and fast transient response during configuration bursts. IC Role / Device Role / Timing Role: Point-of-load converter with 500 kHz forced PWM and 0.8V reference feedback loop. Use Value: ±1% accuracy and 5 V/µs slew rate ensure stable 1.8V/2.5A rail during 100 ns load steps up to 2 A. |
| 24V Industrial Bus Converter | Automotive Body Control Module |
|
Use Scenario: DIN-rail mounted PLC with 24V ±20% input, powering multiple 5V/3.3V subsystems in factory ambient (-40°C to +85°C). IC Role / Device Role / Timing Role: Primary 24V-to-5V buck stage with thermal-foldback and hiccup OCP for reliability. Use Value: 40V absolute max rating and -40°C to +105°C operating range ensure uninterrupted operation during 40V load-dump transients. |
Use Scenario: 12V vehicle battery input powering infotainment USB ports (5V/2A) with cold-crank tolerance (down to 4.5V). IC Role / Device Role / Timing Role: Buck-boost preregulator enabling stable 5V output during engine start (VIN dips to 4.5V). Use Value: Boost-buck topology maintains regulation at 4.5V input with <5% output droop-avoids system reset during cranking. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar buck/boost-buck controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MP2451DT-LF-Z | 36V max input, 0.6A integrated switch, fixed 520 kHz frequency, no boost-buck mode | Limited to low-current buck only; lacks VIN < VOUT capability and programmable frequency | Select for cost-sensitive, low-power 12V bus applications where input never drops below VOUT. |
| LM5118MH/NOPB | 100V max input, external high-/low-side MOSFETs required, 50–500 kHz adjustable frequency | Requires 4 external FETs and complex layout; supports wider input but adds BOM and design effort | Select when input exceeds 40V or when discrete FET optimization (e.g., GaN) is required for >95% efficiency. |
Compared with MP2451DT-LF-Z and LM5118MH/NOPB, the ISL85403FRZ-T uniquely integrates high-side FET and supports boost-buck topology in a compact 4×4 QFN-reducing solution size by 40% versus discrete controllers while enabling operation below VOUT without additional ICs.
Availability
ISL85403FRZ-T is available at Aetrix Electronics and suitable for industrial automation, automotive body electronics, and battery-powered embedded systems requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.
Supply support for ISL85403FRZ-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 specializing in microcontrollers, analog power management, and timing solutions for industrial, automotive, and infrastructure markets.
The ISL85403FRZ-T belongs to Renesas' ISL85xx family of highly integrated DC/DC controllers, designed specifically for space-constrained, high-reliability power conversion in battery-backed and wide-input industrial systems.
FAQ
What is the maximum input voltage rating for the ISL85403FRZ-T?
The ISL85403FRZ-T has an absolute maximum input voltage rating of +44V on the VIN and PHASE pins, with recommended continuous operation up to +40V. This allows safe handling of 24V industrial bus transients and 36V automotive load-dump events while maintaining reliable regulation across its 3V–40V operating range.
How does the ISL85403FRZ-T support operation when input voltage falls below the output voltage?
The ISL85403FRZ-T supports boost-buck operation via its EXT_BOOST pin: when voltage at EXT_BOOST exceeds 200 mV after power-on reset, the IC latches into boost-buck mode and uses LGATE to drive an external boost switch. This enables regulated output even when VIN drops to 2.5V-critical for battery-powered systems during deep discharge.
Can the ISL85403FRZ-T be used in a non-synchronous buck configuration?
Yes-the ISL85403FRZ-T supports non-synchronous buck by disabling the LGATE driver: connect LGATE to VCC through a resistor <5 kΩ before startup. The integrated high-side MOSFET remains active, while an external Schottky diode replaces the synchronous rectifier-simplifying design for cost-sensitive or low-frequency (<300 kHz) applications.
What thermal management is required for the ISL85403FRZ-T at full 2.5A load?
At 2.5A continuous load, the ISL85403FRZ-T requires the exposed thermal pad (PAD) to be soldered to a minimum 200 mm² copper area connected to internal/external ground planes. With this, junction temperature stays ≤125°C at +85°C ambient. Thermal resistance is θJA = 40°C/W and θJC = 3.5°C/W-verified per JEDEC JESD51-7.
Does the ISL85403FRZ-T include built-in protections beyond overcurrent?
Yes-the ISL85403FRZ-T integrates comprehensive protection: overvoltage (110%/120% FB trip), undervoltage (84–96% FB trip), overtemperature (160°C trip / 140°C recovery), and PGOOD monitoring with 128-cycle delay. All protections are fully autonomous and require no external components to activate.
ISL85403FRZ-T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Renesas
- Series:
- -
- Package/Case:
- 20-VFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- 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):
- 40V
- Voltage - Output (Min/Fixed):
- 0.5V
- Voltage - Output (Max):
- 36V
- 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)
ISL85403FRZ-T FAQ
1.How can I place an order for ISL85403FRZ-T through Aetrix?
Please submit a Request for Quotation (RFQ) for ISL85403FRZ-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 ISL85403FRZ-T reliable?
The price and inventory of ISL85403FRZ-T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ISL85403FRZ-T is usually 5 days.
3.What payment methods are accepted for ISL85403FRZ-T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ISL85403FRZ-T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for ISL85403FRZ-T?
ISL85403FRZ-T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your ISL85403FRZ-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 ISL85403FRZ-T?
For technical support, including ISL85403FRZ-T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ISL85403FRZ-T requirements.
6.How does Aetrix verify that ISL85403FRZ-T is sourced from the original manufacturer or authorized distributors?
All ISL85403FRZ-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 ISL85403FRZ-T meets industry standards.
7.What is the process for return or replacement of ISL85403FRZ-T?
All ISL85403FRZ-T units undergo pre-shipment inspection (PSI). If there is an issue with ISL85403FRZ-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 ISL85403FRZ-T part is unused and in its original packaging.
Return procedure for ISL85403FRZ-T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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