My Inquiry
My Account
Renesas ISL85403FRZ
- Part No.:
- ISL85403FRZ
- Manufacturer:
- Renesas
- Package:
- 20-VFQFN Exposed Pad
- Datasheet:
-
ISL85403FRZ.pdf
- Description:
- IC REG BUCK BOOST ADJ 2.5A 20QFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,789
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
ISL85403FRZ from Renesas 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 reliable power delivery in battery-powered industrial sensors and 24V bus point-of-load systems.
For engineers reviewing the ISL85403FRZ datasheet, ISL85403FRZ pinout, ISL85403FRZ application, or ISL85403FRZ equivalent, this page delivers verified technical context, validated pin functions, confirmed topology support (synchronous/non-synchronous buck, two-stage boost-buck), real-world efficiency curves at 5V/3.3V outputs, and precise alternative part comparisons for embedded power design.
Technical Context
The ISL85403FRZ implements peak current mode control with cycle-by-cycle limiting and frequency foldback under overload, plus hiccup-mode recovery for short-circuit robustness. Its dual LDO architecture (main VCC and AUXVCC switchover) enables low-power startup and reduced thermal dissipation during light-load operation.
Topology flexibility is hardware-defined via MODE, EXT_BOOST, and LGATE pins: MODE selects PFM/PWM boundary (default 700 mA); EXT_BOOST >200 mV latches boost-buck mode; LGATE drives external low-side FET or boost switch. Synchronization via SYNC pin supports multi-phase interleaving with automatic 180° phase shift.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3V–40V (buck); down to 2.5V with boost-buck extension - sustains regulation during brownout in battery systems |
| Output Current Rating | 2.5A continuous - defined by thermal limits and internal high-side MOSFET RDS(ON) (140 mΩ @ +25°C) |
| Switching Frequency | 200 kHz–2.2 MHz (programmable via RT resistor) - enables compact magnetics and EMI optimization |
| Voltage Regulation Accuracy | ±1% over line/load/temperature - ensures stable 0.8V reference tracking for precision POL supplies |
| Quiescent Current | 180 µA (PFM, AUXVCC = VOUT) - extends runtime in always-on IoT sensor nodes |
| Protection Features | Cycle-by-cycle OCP with frequency foldback, hiccup-mode recovery, OV/UV/OTP - eliminates need for external fault management circuitry |
| Package | 20-lead 4×4 mm QFN with exposed thermal pad - supports ≤40°C/W θJA with proper PCB copper area |
Pinout & Package
ISL85403FRZ is housed in a RoHS-compliant 20-lead 4×4 mm QFN package (L20.4x4C) with an exposed thermal pad (PAD) requiring direct connection to PCB ground plane for thermal performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| EN (1) | Enable control input | Active-high logic; floating or pulled to VCC enables IC; pulled low disables with ≤4.5 µA shutdown current |
| FS (2) | Frequency select | Open/GND/VCC sets fixed 500 kHz; resistor-to-GND programs 200 kHz–2.2 MHz oscillator |
| SS (3) | Soft-start timing | 5 µA internal current charges external capacitor to control output ramp rate and prevent inrush |
| FB (4) | Feedback sensing | Inverting input of error amplifier; monitors resistive divider to regulate VOUT to 0.8V reference |
| COMP (5) | Error amplifier output | Drives external RC compensation network to stabilize loop response across operating conditions |
| ILIMIT (6) | Current limit programming | Resistor-to-GND sets OCP threshold from default 3.6A; enables design-specific overcurrent protection |
| MODE (7) | PFM/PWM mode selection | Pulled to GND forces PWM; floating/VCC enables PFM below 700 mA (adjustable) for light-load efficiency |
| PGOOD (8) | Power-good status | Open-drain output with 128-cycle delay; asserts high only when VOUT is within ±10% of target |
| PHASE (9,10) | High-side MOSFET source node | Connects directly to inductor; carries full switching current; requires low-inductance layout |
| EXT_BOOST (11) | Boost mode enable & monitoring | Detects >200 mV to latch boost-buck mode; monitors input via resistor divider for UV/OV protection |
| SYNC (12) | External clock synchronization | Accepts square wave (10% higher freq) or connects to other ISL85403s for interleaved operation |
| LGATE (13) | Low-side gate driver | Drives external N-MOSFET in sync-buck or boost switch in boost-buck; disable via 5kΩ pull-up in diode mode |
| PGND (14) | Power ground return | High-current return path for PHASE, LGATE, and drivers; must connect to solid ground plane |
| BOOT (15) | High-side gate bias | Internal bootstrap circuit generates gate drive voltage; 1 µF ceramic cap required between BOOT–PHASE |
| VIN (16,17) | Main supply input | Connects to drain of internal high-side MOSFET and main LDO input; rated 3V–40V |
| SGND (18) | Analog ground reference | Quiet ground for FB, COMP, MODE, ILIMIT - separate from PGND to minimize noise coupling |
| VCC (19) | Main bias regulator output | 4.5V ±0.3V LDO output; powers internal circuitry; requires ≥4.7 µF ceramic decoupling |
| AUXVCC (20) | Auxiliary LDO input/output | In buck mode: 4.5V–20V input for auxiliary LDO; in boost mode: OV detection pin (0.8V threshold) |
| PAD | Thermal pad | Electrically isolated; must be soldered to large PCB ground copper area for θJC = 3.5°C/W |
Key Features
| Feature | Design Value |
|---|---|
| Integrated high-side MOSFET | rDS(ON) = 140 mΩ reduces BOM count and layout complexity vs. external FET controllers |
| Two-stage boost-buck topology support | Extends VIN range down to 2.5V while maintaining regulated VOUT - critical for Li-ion battery systems |
| Programmable PFM/PWM transition | Adjustable current threshold (via MODE pin resistor) optimizes efficiency across load profiles |
| Robust hiccup-mode OCP | Reduces thermal stress during sustained shorts by cycling on/off instead of constant current limiting |
| 180° automatic phase shift in sync mode | Enables seamless multi-phase operation without external timing coordination circuitry |
| AUXVCC switchover | Switches bias supply from main LDO to output rail post-startup, cutting internal power dissipation by ~30% |
Applications
| Industrial Sensor Node Power | 24V Bus Point-of-Load Supply |
|---|---|
|
Use Scenario: Powering ultra-low-power wireless sensor nodes powered by 2S Li-ion (6–8.4V) or 24V industrial bus with brownout resilience. IC Role / Device Role / Timing Role: Primary buck regulator with boost-buck fallback; maintains 3.3V output even as battery drops below 3.3V. Use Value: Enables uninterrupted operation during battery discharge cycles; 180 µA PFM quiescent current extends shelf life. |
Use Scenario: Generating 5V/3.3V rails from noisy 24V factory automation bus with wide input transients. IC Role / Device Role / Timing Role: Synchronous buck controller with 40V absolute max rating and fast transient response. Use Value: Withstands 40V spikes without derating; ±1% regulation ensures stable MCU/I/O voltage under dynamic load steps. |
| Embedded Processor Core Supply | Portable Medical Device Power |
|
Use Scenario: Delivering clean, tightly regulated 1.2V–1.8V core voltage to ARM Cortex-M7 processors in edge AI gateways. IC Role / Device Role / Timing Role: High-efficiency buck converter with programmable soft-start (SS pin) and PGOOD sequencing. Use Value: 200 kHz–2.2 MHz frequency tuning avoids noise-sensitive bands; PGOOD enables safe processor reset sequencing. |
Use Scenario: Powering portable ultrasound or glucose monitor with single-cell Li-ion (2.7–4.2V) and strict low-noise requirements. IC Role / Device Role / Timing Role: Non-synchronous buck (diode rectified) with forced PWM mode for ripple-sensitive analog front-ends. Use Value: Forced PWM eliminates PFM frequency variation; <10 mVPP output ripple at 2A ensures signal integrity in ADC/DAC paths. |
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, no integrated high-side FET, fixed 500kHz frequency, no boost-buck capability | Limited to standard buck; lacks VIN extension below 3V and multi-topology flexibility | Select when cost sensitivity outweighs topology flexibility and 40V rating is unnecessary |
| LM5118MH/NOPB | 65V max input, external high/low FETs required, adjustable frequency (50kHz–1MHz), no PFM mode | Requires more external components; suited for high-voltage industrial inputs but not low-IQ battery apps | Choose for >40V input designs where external FET control and ruggedness are prioritized over integration |
Compared with MP2451DT-LF-Z and LM5118MH/NOPB, the ISL85403FRZ uniquely combines 40V rating, integrated high-side FET, boost-buck topology, and sub-200 µA PFM quiescent current - making it optimal for space-constrained, battery-backed industrial and medical devices requiring both wide VIN and low standby loss.
Availability
ISL85403FRZ is available at Aetrix Electronics and suitable for industrial sensor nodes, 24V bus point-of-load supplies, embedded processor core rails, portable medical devices, and battery-powered edge AI gateways requiring stable component supply across long production lifecycles.
Supply support for ISL85403FRZ 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, and IoT markets.
The ISL85403FRZ belongs to Renesas' ISL85xx family of highly integrated DC/DC controllers, designed specifically for space-constrained, wide-input industrial and battery-powered applications demanding topology flexibility and low-quiescent-power operation.
FAQ
What topologies does the ISL85403FRZ support?
The ISL85403FRZ supports four operational topologies: synchronous buck, non-synchronous buck (using external diode), two-stage boost-buck, and non-inverting single-inductor buck-boost. Mode selection is determined by pin states - EXT_BOOST >200 mV latches boost-buck; MODE pin configures PFM/PWM behavior; LGATE enables or disables low-side FET drive. All configurations use the same ISL85403FRZ silicon and require no firmware changes.
How does the ISL85403FRZ achieve 180 µA quiescent current?
The ISL85403FRZ achieves 180 µA quiescent current in PFM mode only when AUXVCC is tied directly to VOUT, enabling its auxiliary LDO to power internal circuitry with minimal dropout loss. This configuration bypasses the main VCC LDO's higher quiescent draw. The 180 µA value is measured at no load, TA = +25°C, and is validated in the FN8631 datasheet Figure 2 and Electrical Specifications table.
Can the ISL85403FRZ operate with input voltage below 3V?
Yes - the ISL85403FRZ supports input voltages as low as 2.5V when configured in boost-buck mode, enabled by asserting EXT_BOOST >200 mV at power-on. In this mode, the internal low-side driver operates as a boost preregulator, lifting VIN before buck conversion. Below 2.5V, regulation cannot be guaranteed per the datasheet's "Input Voltage" section and Figure 5 schematic.
What is the purpose of the ILIMIT pin on the ISL85403FRZ?
The ILIMIT pin on the ISL85403FRZ programs the cycle-by-cycle overcurrent protection threshold. With ILIMIT floating, connected to GND, or tied to VCC, the default OCP trips at 3.6A. A resistor from ILIMIT to GND scales this threshold linearly - e.g., 100 kΩ yields ~2.5A, 10 kΩ yields ~4.5A - allowing precise current limiting matched to inductor saturation and thermal limits in the final ISL85403FRZ design.
Does the ISL85403FRZ require an external bootstrap diode?
No - the ISL85403FRZ integrates a complete bootstrap charge circuit, eliminating the need for an external bootstrap diode. A 1 µF ceramic capacitor between BOOT and PHASE is mandatory per the datasheet (Page 6, Functional Pin Descriptions), and the internal circuit automatically refreshes the bootstrap voltage during each switching cycle to sustain high-side MOSFET gate drive.
ISL85403FRZ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Renesas
- Series:
- -
- Package/Case:
- 20-VFQFN Exposed Pad
- Packaging:
- Tray
- 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 FAQ
1.How can I place an order for ISL85403FRZ through Aetrix?
Please submit a Request for Quotation (RFQ) for ISL85403FRZ 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 reliable?
The price and inventory of ISL85403FRZ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ISL85403FRZ is usually 5 days.
3.What payment methods are accepted for ISL85403FRZ?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ISL85403FRZ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for ISL85403FRZ?
ISL85403FRZ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your ISL85403FRZ 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?
For technical support, including ISL85403FRZ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ISL85403FRZ requirements.
6.How does Aetrix verify that ISL85403FRZ is sourced from the original manufacturer or authorized distributors?
All ISL85403FRZ 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 meets industry standards.
7.What is the process for return or replacement of ISL85403FRZ?
All ISL85403FRZ units undergo pre-shipment inspection (PSI). If there is an issue with ISL85403FRZ, 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 part is unused and in its original packaging.
Return procedure for ISL85403FRZ:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
ISL85403FRZ Tags
-
TPS562201DDCR
Texas Instruments
-
MC34063ABD-TR
STMicroelectronics
-
TPS561201DDCR
Texas Instruments
-
MC33063ADR
Texas Instruments
-
MC34063ADR
Texas Instruments
-
TPS560200DBVR
Texas Instruments
-
AP3012KTR-G1
Diodes Incorporated
-
TLV61048DBVR
Texas Instruments
-
AZ34063UMTR-G1
Diodes Incorporated
-
TPS562200DDCR
Texas Instruments
-
AP62300TWU-7
Diodes Incorporated
-
MC34063EBD-TR
STMicroelectronics
Tech Hub
TTL and CMOS logic families differ in thresholds, loading, output drive, power and timing. This engineering guide compares 74HC and 74HCT, calculates noise margins and checks 3.3 V/5 V compatibility.
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
