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Analog Devices Inc. LT8494EUF#PBF
- Part No.:
- LT8494EUF#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 20-WFQFN Exposed Pad
- Datasheet:
-
LT8494EUF#PBF.pdf
- Description:
- IC REG BST CHARGE PUMP ADJ 20QFN
- Quantity:
- Payment:
- Shipping:
Inventory:4,673
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Product details
Overview
LT8494EUF#PBF from Analog Devices is a monolithic SEPIC/boost/flyback DC/DC controller IC featuring a 2A/70V NPN power switch, adjustable switching frequency (250kHz–1.5MHz), 7µA quiescent current in active operation, and dual supply pins (VIN/BIAS) enabling operation down to ~1V after startup. It delivers regulated 5V output at up to 1.0A for industrial power supplies and automotive ECUs.
For engineers reviewing the LT8494EUF#PBF datasheet, LT8494EUF#PBF pinout, LT8494EUF#PBF application, or LT8494EUF#PBF equivalent, key selection considerations include its 7µA IQ, 2A/70V integrated switch, programmable UVLO via SWEN, low-ripple Burst Mode operation (<10mV ripple), and fault-tolerant TSSOP package option - all critical for battery-backed and wide-input industrial converters.
Technical Context
The LT8494EUF#PBF implements constant-frequency current-mode control with internal slope compensation, supporting stable operation up to 50% duty cycle without external compensation. Its dual-supply architecture automatically selects between VIN and BIAS for optimal efficiency, enabling operation even when VIN drops below 2.5V post-startup.
It integrates frequency foldback (activates when FB < 1V), soft-start (programmed via SS capacitor), and a precision PG flag (92% VFB threshold). The internal 256kΩ pull-up on SS and 1.202V feedback reference enable accurate output regulation and controlled ramp-up.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switch Rating | 2A continuous, 70V collector-emitter breakdown - supports 60V SEPIC input and 32V boost input with 60V ride-through. |
| Quiescent Current | 7µA from VIN at 12V input - enables >10-year battery life in always-on industrial sensors. |
| Feedback Voltage | 1.202V ±24mV - sets output voltage accuracy; used with resistor divider for precise 5V/12V/15V outputs. |
| Switching Frequency Range | 250kHz to 1.5MHz - selected by RT resistor; higher frequencies allow smaller magnetics and faster transient response. |
| Minimum On/Off Time | 95ns / 70ns - constrains practical duty cycle range and maximum achievable output voltage at high frequencies. |
| Power Good Threshold | 92% of VFB (≈1.106V) - provides reliable output-valid signal for microcontroller sequencing and system safety monitoring. |
| UVLO Programmability | Voltage threshold set via SWEN resistor divider - enables custom input undervoltage lockout without external circuitry. |
Pinout & Package
LT8494EUF#PBF is housed in a 20-lead (4mm × 4mm) plastic QFN package with exposed thermal pad (Pin 21 = GND). The package supports low θJA = 47°C/W and requires soldering of the exposed pad to PCB ground for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SW (Pin 12) | Internal NPN collector node | High-voltage switching node; must minimize trace area to reduce EMI and parasitic inductance. |
| VIN (Pin 10) | Main input supply rail | Accepts 1V–60V input; bypassed locally with 2.2µF ceramic capacitor for stability. |
| BIAS (Pin 16) | Secondary supply input | Enables operation below 2.5V VIN post-startup; connected to output in boost/SEPIC for extended battery runtime. |
| FB (Pin 17) | Output voltage feedback input | Sensed at 1.202V reference; resistor divider sets output voltage and directly impacts load regulation error. |
| PG (Pin 20) | Open-drain power-good flag | Signals VOUT ≥ 92% of target; requires external pull-up for MCU reset or sequencing logic. |
| SWEN (Pin 6) | Enable/UVLO control input | Resistor divider here programs turn-on threshold; 1V hysteresis prevents chatter during brownout. |
| RT (Pin 2) | Oscillator frequency set | Resistor to GND sets switching frequency; values from 41.2kΩ (1.5MHz) to 324kΩ (250kHz). |
| SS (Pin 1) | Soft-start timing node | Charged by internal 256kΩ resistor to ~2.1V; external capacitor controls ramp rate and inrush limiting. |
| GND (Pins 3,4,9,11,13,14,15,21) | System ground reference | Multiple GND pins + exposed pad ensure low-impedance return path for switch current and noise suppression. |
Key Features
| Feature | Design Value |
|---|---|
| Low-ripple Burst Mode® | Maintains <10mV output ripple at light loads while reducing IQ to <3µA - eliminates need for external LDO post-regulation in battery systems. |
| Dual-supply auto-selection | VIN/BIAS comparator with 0.55V hysteresis enables seamless switchover - extends usable battery range by operating down to ~1V input after startup. |
| FMEA fault tolerance | TSSOP variant guarantees output voltage remains within regulation during adjacent-pin shorts or opens - certified for automotive ECU use. |
| Programmable frequency foldback | Reduces max switching frequency when FB < 1V - improves controllability during start-up and short-circuit recovery without external circuitry. |
| Integrated soft-start | 256kΩ internal current source charges external SS capacitor - eliminates discrete timer components and ensures monotonic VOUT ramp. |
Applications
| Automotive ECU Power | Portable Medical Device Supply |
|---|---|
Use Scenario: Powering microcontroller, CAN transceiver, and sensor interface in engine control unit with cold-crank input (4.5V–60V). IC Role / Device Role / Timing Role: Primary DC/DC controller managing SEPIC topology to maintain 5V/3.3V rails across wide battery voltage swings. Use Value: 7µA quiescent current prevents battery drain during vehicle standby; PG flag synchronizes MCU wake-up with valid supply. | Use Scenario: Regulating 5V output from single Li-ion cell (2.7V–4.2V) for portable glucose monitor with display and Bluetooth radio. IC Role / Device Role / Timing Role: Boost converter delivering 500mA at 5V with low-noise operation and fast load transient response. Use Value: Dual-supply operation allows BIAS connection to output, sustaining regulation even as cell voltage drops below 2.5V - extends device runtime by >25%. |
| Industrial Sensor Node | Smart Building HVAC Controller |
Use Scenario: Powering LoRaWAN edge node powered by energy harvesting (1.8V–5.5V input) with intermittent solar charging. IC Role / Device Role / Timing Role: SEPIC regulator providing stable 3.3V rail despite highly variable input; operates in Burst Mode during sleep cycles. Use Value: <10mV output ripple avoids ADC measurement errors; 7µA IQ enables multi-year operation on small supercapacitor buffer. | Use Scenario: Converting 24VAC-derived 32VDC to regulated 5V/12V for thermostat logic, valve drivers, and Zigbee module. IC Role / Device Role / Timing Role: Flyback controller handling 32V input with 60V ride-through capability during line surges. Use Value: 70V switch rating and integrated OVP (34V threshold) eliminate need for external TVS; PG flag validates supply before enabling relay drivers. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar DC/DC controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3789EFE#PBF | 4-switch synchronous buck-boost controller; no integrated switch; requires external MOSFETs; 4V–36V input; 3.5A output capability. | Designed for high-efficiency, high-current buck-boost applications; lacks integrated NPN switch and Burst Mode optimization for ultra-low IQ. | Select LTC3789EFE#PBF only when >3A output or synchronous rectification is required; not drop-in for LT8494EUF#PBF due to different topology and drive architecture. |
| LT3573EDE#PBF | Monolithic 2.5A/65V boost/SEPIC controller; 2.5µA IQ; fixed 1.2MHz frequency; no BIAS pin or dual-supply operation. | Optimized for compact boost designs; lacks programmable UVLO, frequency foldback, and FMEA-rated package variants. | Choose LT3573EDE#PBF for space-constrained boost-only designs where 2.5µA IQ suffices and BIAS-based low-voltage operation is unnecessary. |
Compared with LTC3789EFE#PBF and LT3573EDE#PBF, the LT8494EUF#PBF uniquely combines integrated 2A/70V NPN switching, sub-7µA quiescent current, dual-supply auto-selection, and FMEA-certified packaging - making it the only option for ruggedized, battery-extending SEPIC/boost controllers in automotive and industrial edge nodes.
Availability
LT8494EUF#PBF is available at Aetrix Electronics and suitable for automotive ECU power, portable medical device supply, industrial sensor nodes, and smart building HVAC controllers requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LT8494EUF#PBF 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
Analog Devices (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, serving industrial, automotive, communications, and healthcare markets.
The LT8494 product line was designed specifically for high-reliability, wide-input DC/DC conversion in harsh environments - emphasizing ultra-low quiescent current, fault tolerance, and seamless operation across battery, AC-DC, and energy-harvesting sources.
FAQ
What is the minimum input voltage required for LT8494EUF#PBF startup?
The LT8494EUF#PBF requires a minimum of 2.5V on either VIN or BIAS to initiate startup. Once running, it can sustain operation with VIN as low as ~1V by drawing current from the BIAS pin - a key feature for extending battery life in backup power systems. This behavior is confirmed in the Electrical Characteristics table under "Minimum VIN Operating Voltages" and "Minimum BIAS Operating Voltages".
Does LT8494EUF#PBF support flyback topology, and what isolation requirements apply?
Yes, the LT8494EUF#PBF supports flyback topology using an external transformer and optocoupler feedback loop. It does not integrate primary-side sensing or secondary-side regulation; isolation must be implemented externally. The 70V switch rating limits primary-side clamp voltage and defines maximum reflected output voltage - design must ensure VSW ≤ 70V under all operating and fault conditions per the Absolute Maximum Ratings.
How is the power good (PG) flag of LT8494EUF#PBF configured and used?
The PG pin of LT8494EUF#PBF is an open-drain output that goes high-impedance when FB reaches ≥92% of 1.202V (≈1.106V); an external pull-up resistor is required. It remains low during startup, undervoltage, or overvoltage faults. This signal is used for MCU reset assertion, power sequencing, or system-level health monitoring - verified in the Electrical Characteristics table under "PG Threshold as % of VFB Regulation Voltage".
Can LT8494EUF#PBF operate with input voltages above 32V in boost mode?
Yes - the LT8494EUF#PBF supports up to 60V input in SEPIC topology, and in boost/flyback topologies it tolerates up to 32V for normal operation with ride-through capability up to 60V during transients. This is explicitly stated in the Features section and validated in the Absolute Maximum Ratings (VIN, BIAS Voltage = 60V). Operation above 32V in boost requires careful attention to duty cycle limits and switch stress.
What is the purpose of the NC pins on LT8494EUF#PBF, and can they be tied to ground?
The NC pins on LT8494EUF#PBF (e.g., Pins 5, 7, 8, 18, 19 in QFN) are unconnected internally and must remain floating - especially in the TSSOP package where certain NC pins are designated for FMEA fault tolerance. Tying them to ground or VCC may compromise fault coverage or cause undefined behavior. This requirement is documented in the PIN FUNCTIONS section and Applications Information.
LT8494EUF#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 20-WFQFN Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Function:
- Step-Up, Step-Up/Step-Down
- Output Configuration:
- Positive
- Topology:
- Boost, Charge Pump, Flyback, SEPIC
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 1V
- Voltage - Input (Max):
- 60V
- Voltage - Output (Min/Fixed):
- 1.202V
- Voltage - Output (Max):
- 70V (Switch)
- Current - Output:
- 2A
- Frequency - Switching:
- 250kHz ~ 1.5MHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-QFN (4x4)
LT8494EUF#PBF FAQ
1.How can I place an order for LT8494EUF#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8494EUF#PBF 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 LT8494EUF#PBF reliable?
The price and inventory of LT8494EUF#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT8494EUF#PBF is usually 5 days.
3.What payment methods are accepted for LT8494EUF#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8494EUF#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8494EUF#PBF?
LT8494EUF#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8494EUF#PBF 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 LT8494EUF#PBF?
For technical support, including LT8494EUF#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8494EUF#PBF requirements.
6.How does Aetrix verify that LT8494EUF#PBF is sourced from the original manufacturer or authorized distributors?
All LT8494EUF#PBF 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 LT8494EUF#PBF meets industry standards.
7.What is the process for return or replacement of LT8494EUF#PBF?
All LT8494EUF#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8494EUF#PBF, 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 LT8494EUF#PBF part is unused and in its original packaging.
Return procedure for LT8494EUF#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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