ISL91117IIAZ-T - 4.2A Sync Boost Converter WLCSP-20 | Renesas
MPN: ISL91117IIAZ-T ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $0.62 | $0.62 |
| 10 | $0.56 | $5.60 |
| 100 | $0.49 | $49.00 |
| 500 | $0.42 | $210.00 |
| 1,000 | $0.36 | $360.00 |
ISL91117IIAZ-T Overview
A synchronous boost converter is a switch-mode DC-DC converter that steps the input voltage up to a higher regulated output using an internal high-side MOSFET, an inductor, and a synchronous low-side MOSFET replacing the traditional diode. Within the broader power-management IC hierarchy, the boost converter belongs to step-up switching regulators, which sit alongside buck (step-down), buck-boost, and SEPIC converters. This category trades efficiency against the linear regulator's noise performance: switching converters achieve 90-95% efficiency versus 30-60% for low-dropout (LDO) regulators at large VIN/VOUT deltas, but inject ripple into the output that requires LC filtering. The ISL91117 family targets portable, single-cell Li-ion systems where battery life depends on minimizing quiescent current and maximizing converter efficiency.
The ISL91117IIAZ-T integrates two 4.2A N-channel MOSFETs in a synchronous configuration, supports output disconnect (true shutdown), and operates at a fixed switching frequency optimized for small external components. Internal compensation eliminates the need for external compensation networks. The 20-ball WLCSP occupies approximately 2.015 mm x 1.555 mm of board area, enabling ultra-compact portable designs. Protection features include overcurrent protection, over-temperature shutdown, and undervoltage lockout. The wide input range supports direct connection to single-cell Li-ion batteries without front-end regulation.
Typical applications include boosting a single-cell Li-ion battery (3.0-4.2V) to 5V USB-OTG rails in smartphones, powering 3.3V subsystems from 1.8V rails in wearable devices, and generating 5V supplies from dual-cell alkaline stacks in portable medical and industrial handheld instruments. The 4.2A switch rating also supports LED flash drivers, audio amplifiers, and other high-current loads requiring voltages above the battery.
When designing with the ISL91117IIAZ-T, the critical trade-off is efficiency versus noise: a switching regulator always adds ripple versus an LDO, so for noise-sensitive analog rails downstream LDO post-regulation may still be required. Use the smallest ceramic capacitors that meet the datasheet ESR/ESL guidance to minimize solution size and cost.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the Renesas datasheet, providing engineering context for selecting the ISL91117IIAZ-T versus competing boost converters.
Drop-in alternatives for ISL91117IIAZ-T — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with ISL91117IIAZ-T (same form factor and footprint) — differing in Battery Compatibility, Operating Temperature Range, Output Disconnect, Output Voltage Range.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
ISL91117IIAZ-T7A
✅ Drop-In✓ In Stock
$1.5 / Unit
View Datasheet →ISL91110IIAZ-T
✅ Drop-In📋 Reference alternative (not in catalog)
ISL91127IIAZ-T
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
ISL91117IIAZ-T Maximum Ratings & Electrical Characteristics
| Topology | Synchronous Boost (Step-Up) |
| Input Voltage Range | 1.8 V to 4.8 V |
| Output Voltage Range | Adjustable, 0.8 V up to input voltage range |
| Switch Current Rating | 4.2 A |
| Output Current Capability | 1.5 A at PVIN=3.3V, VOUT=5V |
| Output Disconnect | Yes (true shutdown) |
| Synchronous Rectifier | Yes (integrated low-side MOSFET) |
| Operating Temperature Range | -40 C to +85 C (industrial) |
| Package Type | 20-ball WLCSP (UFBGA), 2.015 mm x 1.555 mm |
| Mounting Type | Surface Mount |
| Battery Compatibility | Single-cell Li-ion/Li-poly, dual/triple-cell alkaline/NiMH/NiCd |
| RoHS Status | Compliant |
| Protection Features | Overcurrent protection, over-temperature shutdown, undervoltage lockout |
ISL91117IIAZ-T Pin Configuration
| Pin A1 | VIN — Battery input voltage (1.8V-4.8V) |
| Pin A2 | PGND — Power ground |
| Pin A3 | SW — Switch node (inductor connection) |
| Pin A4 | SW — Switch node (inductor connection) |
| Pin A5 | VOUT — Boost output voltage |
| Pin B1 | VIN — Battery input voltage |
| Pin B2 | PGND — Power ground |
| Pin B3 | SW — Switch node (inductor connection) |
| Pin B4 | VOUT — Boost output voltage |
| Pin B5 | VOUT — Boost output voltage |
| Pin C1 | AGND — Analog ground |
| Pin C2 | FB — Feedback voltage divider input |
| Pin C3 | EN — Enable (active high) |
| Pin C4 | AGND — Analog ground |
| Pin C5 | VOUT — Boost output voltage |
| Pin D1 | AGND — Analog ground |
| Pin D2 | AGND — Analog ground |
| Pin D3 | AGND — Analog ground |
| Pin D4 | VOUT — Boost output voltage |
| Pin D5 | VOUT — Boost output voltage |
Typical Applications
ISL91117IIAZ-T is suitable for 7 applications: Smartphone USB-OTG 5V Power Rail, Wearable Device 3.3V Boost from 1.8V Coin Cell, Portable Medical Handheld Instrument Power Supply, Industrial IoT Sensor Node Power Conditioning, LED Flash Driver for Camera Phones, Audio Amplifier Supply Rail Boost, Backup Battery System Boost to 3.3V.
Smartphone USB-OTG 5V Power Rail
The ISL91117IIAZ-T's 1.8V to 4.8V input range directly accepts a single-cell Li-ion/Li-polymer battery (3.0-4.2V nominal), and its synchronous boost topology efficiently steps the battery voltage up to the USB-OTG-required 5.0V rail. At PVIN=3.3V and VOUT=5V, the device delivers 1.5A continuous output current - more than enough for USB-OTG peripheral charging at 500mA-1A. The integrated output-disconnect feature eliminates leakage current paths during shutdown, extending battery standby time. The 20-ball WLCSP at 2.015 mm x 1.555 mm fits beneath the SoC or PMIC, preserving precious smartphone PCB real estate.
Recommended
Wearable Device 3.3V Boost from 1.8V Coin Cell
Wearable health monitors and smartwatches often use 1.8V coin-cell or thin-film batteries that cannot directly power 3.3V Bluetooth Low Energy (BLE) SoCs and sensor ICs. The ISL91117IIAZ-T accepts the 1.8V input and boosts it to a stable 3.3V output while drawing only microamps of quiescent current during light loads. The 4.2A switch current rating comfortably supports peak load transients from BLE radio transmissions (typically 30-50mA) and sensor sampling bursts (5-20mA). The synchronous rectifier and true shutdown minimize idle battery drain, critical for multi-week wearable battery life.
Recommended
Portable Medical Handheld Instrument Power Supply
Handheld medical devices such as glucose meters, pulse oximeters, and infusion pumps run from dual-cell alkaline (3V) or single-cell Li-ion (3.7V) batteries but need a regulated 5V rail to power displays, op-amps, and isolated communication interfaces. The ISL91117IIAZ-T boosts the battery to 5V with 1.5A capability, enough to drive an LCD backlight, audio beeper, and microcontroller simultaneously. The integrated over-temperature and over-current protection features meet IEC 60601 medical safety design expectations. Renesas' long-term reliability track record and the WLCSP-20 miniaturization enable pocket-sized medical form factors.
Recommended
Industrial IoT Sensor Node Power Conditioning
Industrial IoT (IIoT) sensor nodes frequently operate from 3.6V lithium-thionyl-chloride (Li-SOCl2) primary batteries that sag under load and cannot directly power 3.3V wireless MCUs. The ISL91117IIAZ-T boosts the variable battery voltage (2.5V-3.6V) to a regulated 3.3V output, supporting continuous sensor operation even as the battery discharges. The 4.2A switch rating accommodates transmit bursts from LoRa, Sigfox, or Wireless MBus radios that can pull 100-300mA during transmission. The 20-ball WLCSP and minimal external component count keep the sensor node BOM small for high-volume industrial deployments.
Recommended
LED Flash Driver for Camera Phones
Modern smartphone camera flashes require brief high-current pulses (up to 1-2A) to drive high-brightness white LEDs from a single-cell Li-ion battery. The ISL91117IIAZ-T's 4.2A switch current and 1.5A continuous output capability make it suitable for driving LED flash circuits when boosted above the battery voltage. The synchronous topology minimizes thermal dissipation during the brief flash pulse, and the WLCSP package keeps the boost inductor and capacitor loop compact for clean switching. This is a niche but well-documented application in portable-camera product designs.
Recommended
Audio Amplifier Supply Rail Boost
Portable audio devices (Bluetooth speakers, headphone amplifiers) often use a single-cell Li-ion battery but need a higher voltage (typically 5V-9V) to drive Class-D or Class-AB audio amplifiers for louder output. The ISL91117IIAZ-T boosts the 3.7V battery to a 5V or 7V rail, providing headroom for amplifier power output. The synchronous rectification delivers 90-95% efficiency, extending playback time. The WLCSP-20 package fits alongside the audio codec in space-constrained portable speaker designs.
Recommended
Backup Battery System Boost to 3.3V
Uninterruptible power supplies (UPS) and memory backup systems often use supercapacitor or thin-film batteries that sag from 3.0V to 2.0V during discharge. The ISL91117IIAZ-T boosts the variable backup-battery voltage to a stable 3.3V output, ensuring RTC circuits, SRAM, and monitoring ICs continue operating during main-power outages. The 1.8V minimum input covers deep-discharge supercapacitor scenarios. The integrated output disconnect prevents reverse current flow back into the battery, preserving backup charge for critical power-loss events.
Recommended
Recommended Products Summary
Engineering reference data for ISL91117IIAZ-T — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ISL91117IIAZ-T7A | ISL91110IIAZ-T | ISL91127IIAZ-T |
|---|---|---|---|---|
| Brand | Renesas Electronics | Renesas Electronics | Renesas Electronics | Renesas Electronics |
| Package | 20-ball WLCSP (2.015 mm x 1.555 mm) | 20-ball WLCSP - same | 20-ball WLCSP - same | 20-ball WLCSP - same |
| Topology | Synchronous Boost | Synchronous Boost | Synchronous Boost | Synchronous Boost |
| Switch Current Rating | 4.2 A | 4.2 A | ~2 A | ~3 A |
| Reel Quantity | 3000 (T-suffix) | 250 (T7A-suffix) | 3000 (T-suffix) | 3000 (T-suffix) |
Key Differentiators
- 4.2A switch current rating in WLCSP-20 (vs ISL91110IIAZ-T)
- True output-disconnect in shutdown (vs ISL91110IIAZ-T)
- Synchronous rectification for higher efficiency (vs Non-synchronous boost alternatives (e.g. TL2575-05IKV))
- Wide 1.8V-4.8V input range for single Li-ion (vs Buck-only alternatives (e.g. TPS61236 in buck mode))
Design Notes
WLCSP-20 layout requires careful PCB design: keep all bypass and decoupling capacitors within 2 mm of their respective balls. Use a 4-layer PCB with a dedicated ground plane beneath the IC to minimize the high-current switching loop area. The SW node traces must be short and wide (>= 0.5 mm) to reduce parasitic inductance that causes voltage spikes and EMI. Estimated: with 2 mm x 0.3 mm SW traces at 4.2A, expect approximately 10-15 nH of parasitic inductance per trace.
Although the WLCSP package is small, the ISL91117IIAZ-T can dissipate 0.5-1.5W in typical battery-to-5V boost operation. The thermal pad and ground balls carry heat to the PCB; ensure at least 50 mm^2 of copper pour on the top layer connected to PGND and AGND balls for heat spreading. For continuous 1.5A output operation, additional PCB thermal relief or airflow may be required to keep junction temperature below 125C. Estimated: at 1.5A output with 3.3V input to 5V boost, power dissipation is approximately 1.05W (assuming 90% efficiency).
Common ISL91117 design pitfalls include: (1) using an inductor with insufficient saturation current - select >= 5A saturation to handle 4.2A switch transients; (2) omitting the input bypass capacitor - always place >= 10uF ceramic directly at VIN; (3) leaving EN floating - tie EN to VIN through a 100k resistor for default-on operation; (4) ignoring output-disconnect behavior - if your circuit requires the output to remain energized in shutdown, add an external Schottky diode; (5) exceeding absolute maximum VIN of 5.5V during transients. (Source: Renesas ISL91117 datasheet application notes.)
The WLCSP-20 ball map requires exact land pattern matching - refer to the Renesas ISL91117 datasheet land pattern appendix for ball pitch (typically 0.4 mm) and pad diameter recommendations. The SW node balls must connect to the inductor with the shortest possible trace to minimize EMI. Place the input capacitor return via directly to the nearest PGND ball, not to a remote ground point, to keep the high-current loop compact and reduce conducted noise.
Compliance Information
RoHS and REACH compliance per Renesas product page. AEC-Q100 not qualified - this part targets commercial/industrial portable applications, not automotive. Lead-free reflow compatible per JEDEC J-STD-020.
