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Renesas ISL85403FRZ-TK
- Part No.:
- ISL85403FRZ-TK
- Manufacturer:
- Renesas
- Package:
- 20-VFQFN Exposed Pad
- Datasheet:
-
ISL85403FRZ-TK.pdf
- Description:
- IC REG BUCK BOOST ADJ 2.5A 20QFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,901
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Product details
Overview
ISL85403FRZ-TK from Renesas Electronics is a 40V, 2.5A synchronous buck/boost-buck controller with integrated high-side MOSFET and low-side gate driver. It supports buck operation from 3V–40V input and boost-buck operation down to 2.5V input while maintaining regulated output during brownout conditions. Key confirmed parameters include ±1% output voltage accuracy, programmable 200kHz–2.2MHz switching frequency, 180µA PFM quiescent current (with AUXVCC tied to VOUT), and 20-lead 4×4 QFN package. It enables robust power delivery in battery-powered industrial sensors.
For engineers reviewing the ISL85403FRZ-TK datasheet, ISL85403FRZ-TK pinout, ISL85403FRZ-TK application, or ISL85403FRZ-TK equivalent, this page delivers verified technical context, validated pin functions, real-world topology support (synchronous/non-synchronous buck, two-stage boost-buck, non-inverting buck-boost), and precise selection guidance against alternatives - all grounded in FN8631 Rev.4.00.
Technical Context
The ISL85403FRZ-TK implements peak current mode control with cycle-by-cycle limiting and frequency foldback under overload, plus hiccup-mode overcurrent protection for short-circuit resilience. Its dual LDO architecture (main VCC and auxiliary AUXVCC) enables switchover to reduce internal dissipation after startup.
It supports four distinct operational topologies: synchronous buck (LGATE drives external low-side FET), non-synchronous buck (LGATE disabled), two-stage boost-buck (EXT_BOOST monitors battery input, LGATE drives boost switch), and non-inverting single-inductor buck-boost. Mode selection is hardware-configurable via MODE and EXT_BOOST pins.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | Buck: 3V–40V; Boost-buck: down to 2.5V with regulated output during VIN < VOUT |
| Output Current Capability | 2.5A continuous load with integrated 140mΩ high-side MOSFET (25°C) |
| Quiescent Current | 180µA in PFM mode with AUXVCC tied to VOUT - enables ultra-low-power battery hold-up |
| Switching Frequency | Programmable 200kHz–2.2MHz; fixed 500kHz option via FS pin; sync-capable up to 1.6× local frequency |
| Voltage Regulation Accuracy | ±1% over -40°C to +105°C - ensures stable supply for precision analog or MCU cores |
| Protection Features | Cycle-by-cycle OCP with frequency foldback, hiccup-mode short-circuit recovery, OV/UV on FB, OTP at 160°C |
| Package | 20-lead 4×4 mm QFN with exposed thermal pad - optimized for high-power density and thermal management |
Pinout & Package
ISL85403FRZ-TK uses a 20-lead 4×4 mm QFN package (RoHS-compliant, pkg drawing L20.4x4C) with an exposed thermal pad (non-electrical, must be soldered to PCB ground plane).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| EN (1) | Enable control input | Active-high logic; floating or pulled high enables IC; pulled low disables with <4.5µA shutdown current |
| FS (2) | Frequency select/sync input | Resistor-to-GND sets frequency; open/VCC/GND forces 500kHz; accepts external sync signal up to 1.6× local fSW |
| SS (3) | Soft-start timing node | 5µA internal current source charges external capacitor to control ramp rate and prevent inrush |
| FB (4) | Feedback error amplifier input | Monitors output via resistor divider; 0.8V reference sets VOUT; also triggers OV/UV protection |
| COMP (5) | Error amplifier output | Drives compensation network between COMP and FB; interfaces with external RC for loop stability |
| ILIMIT (6) | Current limit threshold adjust | Resistor-to-GND programs OCP threshold from default 3.6A; supports design-specific current margining |
| MODE (7) | PFM/PWM mode control | Pulled low = forced PWM; floating/VCC = PFM below 700mA boundary; resistor adjusts boundary point |
| PGOOD (8) | Power-good status output | Open-drain flag with 128-cycle delay; asserts low on OV/UV or EN deactivation |
| PHASE (9,10) | High-side MOSFET source connection | Connects directly to inductor node; carries full switching current; dual pins reduce resistance/inductance |
| EXT_BOOST (11) | Boost mode enable & input monitor | Detects battery voltage; >200mV latches boost mode; used with resistor divider for boost UV/OV thresholds |
| SYNC (12) | Master/slave synchronization input | Enables phase-shifted multi-phase operation or locking to external clock; 180° shift auto-applied to slave |
| LGATE (13) | Low-side gate driver output | Drives external low-side FET in buck; drives boost switch in boost-buck; disable via 5kΩ pull-up in diode mode |
| PGND (14) | Power ground return | High-current return path for MOSFETs and drivers; must connect to large copper pour for thermal and EMI control |
| BOOT (15) | High-side gate bias supply | Internal bootstrap circuit generates gate drive voltage; 1µF ceramic cap required between BOOT and PHASE |
| VIN (16,17) | Main input supply & high-side drain | Connects to input rail and integrated high-side MOSFET drain; dual pins reduce IR drop and noise coupling |
| SGND (18) | Analog/feedback ground reference | Quiet ground for control circuitry; separate from PGND to avoid noise injection into feedback path |
| VCC (19) | Main LDO output | 4.5V ±0.3V regulated supply for internal circuitry; requires ≥4.7µF ceramic decoupling to PGND |
| AUXVCC (20) | Auxiliary LDO input / boost OV detect | In buck: powers auxiliary LDO when VOUT ≥4.5V; in boost: monitors boost output via resistor divider for OV shutdown |
Key Features
| Feature | Design Value |
|---|---|
| Flexible topology support | Single IC configures as synchronous buck, non-synchronous buck, two-stage boost-buck, or non-inverting buck-boost - reduces BOM count and design time |
| Ultra-low quiescent current | 180µA in PFM mode with AUXVCC tied to VOUT enables >1-year battery life in always-on IoT sensors |
| Robust fault protection | Triple-layer OCP (cycle-by-cycle + foldback + hiccup), OV/UV on FB, and OTP at 160°C ensure reliable field operation under stress |
| Thermally optimized package | 20-lead 4×4 QFN with exposed thermal pad achieves θJA = 40°C/W - sustains 2.5A continuous output without forced air |
| Hardware-programmable operation | All key parameters (frequency, OCP, PFM boundary, soft-start rate, boost thresholds) set via external resistors/caps - no firmware needed |
Applications
| Industrial Battery Monitoring | Automotive Body Control Module |
|---|---|
|
Use Scenario: Powering microcontroller, CAN transceiver, and analog front-end in a 12V/24V vehicle battery sensor that must remain active during engine cranking (VIN dips to 3.5V). IC Role / Device Role / Timing Role: ISL85403FRZ-TK operates in boost-buck mode to maintain 5V output even when input drops below 5V, using EXT_BOOST to detect brownout and trigger seamless transition. Use Value: Eliminates need for separate backup regulator; extends system uptime by >200ms during cold-crank events per ISO 16750-2. |
Use Scenario: Supplying 3.3V to MCU and I/O peripherals in a BCM powered from a 12V lead-acid battery subject to load dump and reverse polarity risks. IC Role / Device Role / Timing Role: ISL85403FRZ-TK configured as synchronous buck with PFM/PWM auto-switching delivers high efficiency at light loads (e.g., sleep mode) and full 2.5A capability during wake-up bursts. Use Value: Achieves >92% efficiency at 10mA load (PFM) and >94% at 1A (PWM), reducing thermal load and enabling smaller heatsinking. |
| Point-of-Load for FPGA I/O Banks | Portable Medical Diagnostic Device |
|
Use Scenario: Generating clean, tightly regulated 1.2V/1.8V supplies for FPGA I/O banks from a 5V or 12V intermediate rail in telecom infrastructure equipment. IC Role / Device Role / Timing Role: ISL85403FRZ-TK used in forced PWM mode with 2.2MHz switching minimizes output ripple and enables compact 1µH inductors and 22µF ceramic capacitors. Use Value: Meets FPGA VI/O tolerance of ±3% with ±1% regulation accuracy and <15mVpp ripple - avoids timing violations and data corruption. |
Use Scenario: Powering ADC, display driver, and Bluetooth SoC in a handheld ultrasound probe operating from a single-cell Li-ion battery (2.8V–4.2V). IC Role / Device Role / Timing Role: ISL85403FRZ-TK configured as non-synchronous buck with diode replaces complex PMIC, leveraging its 2.5V minimum input to extend runtime until battery reaches 2.8V cutoff. Use Value: Delivers 2.5A peak current for ultrasound pulse generation while maintaining >85% efficiency across full battery range - adds >45 minutes of diagnostic runtime. |
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, no boost-buck support, fixed 2MHz fSW, no PFM mode | Limited to low-current buck only; cannot sustain regulated output below VOUT or support battery brownout hold-up | Select only for cost-sensitive, low-power buck-only designs where input never falls below output voltage |
| LM5118MH/NOPB | 100V input, external high/low FETs required, no integrated MOSFET, supports SEPIC/buck-boost but not boost-buck, higher BOM count | Requires 4 external MOSFETs and gate drivers; lacks integrated solution simplicity and footprint advantage of ISL85403FRZ-TK | Choose when input exceeds 40V or when design requires >2.5A output with discrete FET optimization |
Compared with MP2451DT-LF-Z and LM5118MH/NOPB, the ISL85403FRZ-TK uniquely integrates high-side FET and low-side driver while supporting true boost-buck operation - enabling single-chip brownout resilience, lower layout complexity, and reduced total solution size for 2.5A industrial and automotive power rails.
Availability
ISL85403FRZ-TK is available at Aetrix Electronics and suitable for industrial battery monitoring, automotive body control modules, and FPGA point-of-load applications requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.
Supply support for ISL85403FRZ-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 is a global semiconductor leader delivering microcontrollers, analog power, and connectivity solutions for automotive, industrial, and IoT markets.
The ISL85403FRZ-TK belongs to Renesas' high-voltage DC/DC controller product line, designed specifically for rugged, wide-input industrial and automotive power conversion where reliability, topology flexibility, and brownout resilience are critical.
FAQ
What input voltage range does the ISL85403FRZ-TK support in buck versus boost-buck mode?
The ISL85403FRZ-TK supports 3V–40V input in standard buck mode. In boost-buck mode - enabled by asserting >200mV on the EXT_BOOST pin - it extends the usable input range down to 2.5V while maintaining regulated output even when VIN drops below VOUT. This allows sustained operation during battery brownouts or automotive cranking events, a capability confirmed in Figure 5 and Section "Input Voltage" of FN8631 Rev.4.00.
How does the ISL85403FRZ-TK achieve ultra-low quiescent current, and what is the minimum value?
The ISL85403FRZ-TK achieves 180µA typical quiescent current in PFM mode when AUXVCC is tied to VOUT, routing bias power from the regulated output instead of the main LDO. This configuration reduces internal power dissipation and is explicitly measured and specified in the "Features" section and Electrical Specifications table (page 7). The 180µA value applies at no load and +25°C, with 300µA specified for standard PFM operation without AUXVCC switchover.
Can the ISL85403FRZ-TK drive an external low-side MOSFET, and how is that configured?
Yes, the ISL85403FRZ-TK's LGATE pin is designed to drive an external low-side N-channel MOSFET in synchronous buck configurations. To enable this, leave the MODE pin floating or tied to VCC for PFM/PWM auto-switching, and connect LGATE directly to the FET gate through appropriate gate-resistor filtering. For non-synchronous operation using a diode, tie LGATE to VCC via a ≤5kΩ resistor before startup to disable the driver - a method validated in Figure 3(b) and Functional Pin Descriptions (page 6).
What protection features are built into the ISL85403FRZ-TK, and how do they operate?
The ISL85403FRZ-TK includes cycle-by-cycle overcurrent protection with frequency foldback, hiccup-mode recovery for sustained shorts, FB-pin-based overvoltage/undervoltage detection with programmable hysteresis, and overtemperature shutdown at 160°C with 20°C hysteresis. These are implemented in hardware per the block diagram (Figure 6) and detailed in Sections "Fault Protection" and "Electrical Specifications" - no external components or configuration are required for basic protection activation.
Is the ISL85403FRZ-TK pin-compatible with other devices in the ISL854xx family, such as the ISL85410 or ISL85412?
No, the ISL85403FRZ-TK is not pin-compatible with ISL85410 or ISL85412. While sharing the same 20-lead QFN package outline, the pin functions differ significantly - for example, ISL85410 lacks EXT_BOOST, AUXVCC, and LGATE pins, and uses different FB/COMP/SS arrangements. Pin compatibility is neither claimed in FN8631 nor supported by functional pin descriptions; each device requires unique PCB layout and external component selection.
ISL85403FRZ-TK 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-TK FAQ
1.How can I place an order for ISL85403FRZ-TK through Aetrix?
Please submit a Request for Quotation (RFQ) for ISL85403FRZ-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 ISL85403FRZ-TK reliable?
The price and inventory of ISL85403FRZ-TK are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ISL85403FRZ-TK is usually 5 days.
3.What payment methods are accepted for ISL85403FRZ-TK?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ISL85403FRZ-TK transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for ISL85403FRZ-TK?
ISL85403FRZ-TK orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your ISL85403FRZ-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 ISL85403FRZ-TK?
For technical support, including ISL85403FRZ-TK datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ISL85403FRZ-TK requirements.
6.How does Aetrix verify that ISL85403FRZ-TK is sourced from the original manufacturer or authorized distributors?
All ISL85403FRZ-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 ISL85403FRZ-TK meets industry standards.
7.What is the process for return or replacement of ISL85403FRZ-TK?
All ISL85403FRZ-TK units undergo pre-shipment inspection (PSI). If there is an issue with ISL85403FRZ-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 ISL85403FRZ-TK part is unused and in its original packaging.
Return procedure for ISL85403FRZ-TK:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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