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Renesas ISL91108SIIAZ-T
- Part No.:
- ISL91108SIIAZ-T
- Manufacturer:
- Renesas
- Package:
- 20-UFBGA, WLCSP
- Datasheet:
-
ISL91108SIIAZ-T.pdf
- Description:
- IC REG BUCK BST ADJ 3.7A 20WLCSP
- Quantity:
- Payment:
- Shipping:
Inventory:1,376
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Product details
Overview
ISL91108SIIAZ-T from Intersil is a fully synchronous 4-switch buck-boost DC/DC regulator delivering up to 1.6A DC output current (PVIN = 2.8V, VOUT = 3.3V), supporting adjustable output voltages from 1.0V to 5.2V via external resistor divider, and operating across 1.8V–5.5V input range with 27.5µA no-load quiescent current. It enables compact power solutions in space-constrained mobile applications requiring seamless buck-to-boost transition.
For engineers reviewing the ISL91108SIIAZ-T datasheet, ISL91108SIIAZ-T pinout, ISL91108SIIAZ-T application, or ISL91108SIIAZ-T equivalent, key selection criteria include its 2.6MHz switching frequency for small external components, automatic PFM/PWM mode transition thresholds (75mA/200mA), thermal shutdown at 150°C, and WLCSP package compatibility with high-density PCB layouts.
Technical Context
The ISL91108SIIAZ-T implements a true 4-switch buck-boost topology with independent gate drivers and anti-shoot-through logic, enabling continuous conduction mode operation and automatic mode transitions without output voltage disturbance. Its internal reference maintains 0.788V–0.812V FB pin regulation for precise output programming.
It integrates undervoltage lockout (1.725V rising threshold), short-circuit protection via FB monitoring, and soft-discharge functionality (110Ω internal pull-down on EN deassertion). The MODE/SYNC pin supports both auto PFM mode selection and external clock synchronization from 2.75MHz to 3.25MHz.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 1.8V to 5.5V - supports single-cell Li-ion, Li-polymer, and multi-cell alkaline battery inputs without pre-regulation. |
| Output Current (DC) | Up to 1.6A - sufficient for powering RF power amplifiers, application processors, and PMIC rails in smartphones. |
| Switching Frequency | 2.4MHz to 2.9MHz (typ. 2.6MHz) - enables use of 1µH inductors and minimizes footprint of ceramic capacitors. |
| Quiescent Current | 27.5µA - extends battery runtime in standby and low-power listening modes. |
| FB Reference Voltage | 0.788V to 0.812V - ensures ±2% output accuracy over temperature and line/load conditions for adjustable configurations. |
| Thermal Shutdown | 150°C with 35°C hysteresis - protects against sustained overload or poor heatsinking in sealed enclosures. |
| Package | 20-bump WLCSP (2.34mm × 1.72mm, 0.4mm pitch) - compatible with fine-pitch SMT assembly and ultra-thin mobile form factors. |
Pinout & Package
ISL91108SIIAZ-T uses a 20-bump Wafer-Level Chip-Scale Package (WLCSP) with 0.4mm pitch, measuring 2.34mm × 1.72mm. The package exposes solder bumps on the die side and requires standard Pb-free reflow profile per J-STD-020.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A5, B5, C5 | VOUT | Main regulated output node; connects to dual 22µF X5R ceramic capacitors for low-ESR filtering and transient response. |
| A4, B4, C4 | LX2 | Boost-side switch node; connects to one end of the 1µH inductor and must be routed with minimal loop area to reduce EMI. |
| A3, B3, C3 | PGND | Power ground return for high di/dt switching currents; requires dedicated low-impedance copper pour under package. |
| A2, B2, C2 | LX1 | Buck-side switch node; connects to other end of inductor and shares PGND return path with LX2. |
| A1, B1, C1 | PVIN | Main power input (1.8V–5.5V); decoupled with dual 10µF X5R ceramics placed adjacent to pins. |
| D1 | VIN | Analog supply for internal reference and control circuitry; separate from PVIN to improve PSRR and stability. |
| D2 | EN | Active-high enable input; asserts internal soft-start and disables soft-discharge when pulled high. |
| D3 | MODE/SYNC | Selects PFM (HIGH) or forced PWM (LOW); accepts 2.75–3.25MHz external clock for EMI reduction. |
| D4 | GND | Analog ground reference; isolated from PGND to prevent noise coupling into feedback path. |
| D5 | FB | Feedback input for adjustable output; senses divided VOUT with ≤0.2µA bias current to minimize divider error. |
Key Features
| Feature | Design Value |
|---|---|
| Automatic Buck-Boost Mode Transition | Seamless switching between buck and boost without output voltage glitch or control-loop instability during VIN crossing VOUT. |
| 4-Switch Synchronous Architecture | Eliminates external Schottky diodes and achieves up to 95% peak efficiency by minimizing conduction losses in both modes. |
| 2.6MHz Fixed-Frequency Operation | Reduces required inductor size to 1µH and allows use of compact 0603/0805 MLCCs without compromising transient response. |
| Integrated Soft-Discharge | 110Ω internal pull-down on VOUT during shutdown prevents floating rail and eliminates need for external bleed resistor. |
| Low IQ with PFM Mode | 27.5µA quiescent current in PFM extends battery life in always-on sensors and IoT edge nodes with intermittent activity. |
Applications
| Smartphone Core Power | Tablet PMIC Auxiliary Rail |
|---|---|
Use Scenario: Supplying 3.3V or 4.2V core voltage to application processors during dynamic DVFS transitions where battery voltage drops from 4.2V to 3.0V. IC Role / Device Role / Timing Role: Primary buck-boost regulator maintaining stable output while seamlessly transitioning between buck (VIN > VOUT) and boost (VIN < VOUT) as battery discharges. Use Value: Eliminates need for separate buck + boost converters, reducing BOM count by two ICs and saving >15mm² PCB area. | Use Scenario: Generating 1.8V I/O rail for display interface controllers in tablets powered by 3.7V nominal Li-ion batteries. IC Role / Device Role / Timing Role: Adjustable-output DC/DC converter configured via external resistors to deliver precise 1.8V with ±2% accuracy across load and temperature. Use Value: Enables direct connection to battery without intermediate LDO, improving system efficiency by 12% versus linear regulation at 1.2A load. |
| 2G/3G/4G PA Bias Supply | Wireless Headset Audio Codec Power |
Use Scenario: Providing 5.0V bias to RF power amplifiers in cellular handsets where input varies from 3.4V (low battery) to 4.4V (charged). IC Role / Device Role / Timing Role: High-current buck-boost regulator delivering up to 1.6A DC with burst capability to support PA envelope tracking peaks. Use Value: Maintains constant PA gain and linearity across full battery range, avoiding transmit power droop and regulatory compliance risk. | Use Scenario: Powering low-noise audio codecs in Bluetooth headsets requiring clean 3.3V supply with minimal ripple during voice calls. IC Role / Device Role / Timing Role: Synchronized PWM-mode regulator locked to system clock to shift switching noise out of audio band (20Hz–20kHz). Use Value: Reduces conducted EMI by 18dB compared to free-running operation, eliminating audible switching artifacts in analog audio paths. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar buck-boost regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS63020DSJR | Lower max output current (1.2A DC), fixed 3.3V option only; lacks external sync capability and soft-discharge function. | Suitable for lower-power wearables but not for 2G/3G PA bias where 1.6A+ burst is required. | Choose ISL91108SIIAZ-T when adjustable output, higher current, or EMI-sensitive sync is needed. |
| MAX77827AEWE+T | Higher IQ (45µA), supports wider input (0.5V–5.5V), but uses larger 2.5mm × 2.5mm WLP package and lacks 2.6MHz high-frequency option. | Better for ultra-low-power IoT sensors, but less optimal for thin smartphone bezels requiring sub-4mm² solution size. | Choose ISL91108SIIAZ-T when board area is constrained and 2.6MHz operation is critical for component miniaturization. |
Compared with TPS63020DSJR and MAX77827AEWE+T, the ISL91108SIIAZ-T uniquely combines 1.6A DC output, 2.6MHz switching, integrated soft-discharge, and 2.34mm × 1.72mm WLCSP-enabling the smallest total solution size for battery-powered portable devices demanding wide VIN/VOUT flexibility.
Availability
ISL91108SIIAZ-T is available at Aetrix Electronics and suitable for smartphone core power, tablet auxiliary rails, 2G/3G/4G PA bias supplies, and wireless headset audio codec power requiring stable component supply across high-volume production cycles.
Supply support for ISL91108SIIAZ-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
Intersil Corporation is a leading provider of precision analog and power management ICs, now part of Renesas Electronics, with expertise in high-efficiency DC/DC conversion and battery-powered system optimization.
The ISL91108 product line was designed specifically for space-constrained mobile platforms requiring seamless buck-boost regulation across full battery discharge curves without sacrificing efficiency or transient performance.
FAQ
What output voltage range does the ISL91108SIIAZ-T support?
The ISL91108SIIAZ-T supports an adjustable output voltage range from 1.0V to 5.2V using an external resistor divider connected to the FB pin. Its internal FB reference voltage is tightly regulated between 0.788V and 0.812V, enabling precise output programming with ±2% accuracy over temperature and load. This makes the ISL91108SIIAZ-T suitable for diverse rail requirements in portable electronics without needing multiple fixed-output variants.
How does the ISL91108SIIAZ-T handle transitions between buck and boost modes?
The ISL91108SIIAZ-T automatically and seamlessly transitions between buck and boost modes based on real-time comparison of PVIN and VOUT, with no output voltage disturbance or control-loop interruption. Its 4-switch architecture and proprietary PWM controller ensure continuous conduction and smooth duty-cycle adjustment during VIN crossing VOUT-critical for maintaining stable processor core voltage during battery discharge in smartphones and tablets.
What is the purpose of the MODE/SYNC pin on the ISL91108SIIAZ-T?
The MODE/SYNC pin on the ISL91108SIIAZ-T serves dual functions: when pulled HIGH, it enables automatic PFM mode for light-load efficiency; when pulled LOW, it forces continuous PWM operation. Additionally, applying a 2.75MHz–3.25MHz external clock signal to this pin synchronizes the ISL91108SIIAZ-T's internal oscillator, allowing EMI noise to be shifted away from sensitive frequency bands-essential for audio and RF subsystems.
Does the ISL91108SIIAZ-T include built-in protection features?
Yes, the ISL91108SIIAZ-T integrates short-circuit protection (via FB voltage monitoring), thermal shutdown (150°C with 35°C hysteresis), undervoltage lockout (1.725V rising threshold), and reverse-current blocking. These protections operate independently of external components and remain active across all operating modes-including PFM, PWM, and external sync-ensuring robust field reliability in consumer and industrial portable equipment.
What is the recommended inductor value and saturation current for the ISL91108SIIAZ-T?
The ISL91108SIIAZ-T is optimized for a 1µH shielded ferrite inductor rated for ≥4.0A saturation current, such as Toko 1277AS-H-1R0M or Coilcraft XFL4020-102ME. This value balances low DC resistance for high efficiency, sufficient energy storage for 2.6MHz operation, and headroom for 2.7A burst current. Using an inductor with lower saturation rating risks core saturation and loss of regulation under peak load conditions.
ISL91108SIIAZ-T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Renesas
- Series:
- -
- Package/Case:
- 20-UFBGA, WLCSP
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Function:
- Step-Up/Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck-Boost
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 1.8V
- Voltage - Input (Max):
- 5.5V
- Voltage - Output (Min/Fixed):
- 1V
- Voltage - Output (Max):
- 5.2V
- Current - Output:
- 3.7A (Switch)
- Frequency - Switching:
- 2.6MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-WLCSP
ISL91108SIIAZ-T FAQ
1.How can I place an order for ISL91108SIIAZ-T through Aetrix?
Please submit a Request for Quotation (RFQ) for ISL91108SIIAZ-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 ISL91108SIIAZ-T reliable?
The price and inventory of ISL91108SIIAZ-T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ISL91108SIIAZ-T is usually 5 days.
3.What payment methods are accepted for ISL91108SIIAZ-T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ISL91108SIIAZ-T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for ISL91108SIIAZ-T?
ISL91108SIIAZ-T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your ISL91108SIIAZ-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 ISL91108SIIAZ-T?
For technical support, including ISL91108SIIAZ-T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ISL91108SIIAZ-T requirements.
6.How does Aetrix verify that ISL91108SIIAZ-T is sourced from the original manufacturer or authorized distributors?
All ISL91108SIIAZ-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 ISL91108SIIAZ-T meets industry standards.
7.What is the process for return or replacement of ISL91108SIIAZ-T?
All ISL91108SIIAZ-T units undergo pre-shipment inspection (PSI). If there is an issue with ISL91108SIIAZ-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 ISL91108SIIAZ-T part is unused and in its original packaging.
Return procedure for ISL91108SIIAZ-T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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