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Analog Devices Inc. LT3598EFE#PBF
- Part No.:
- LT3598EFE#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 24-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LT3598EFE#PBF.pdf
- Description:
- IC LED DRV RGLTR PWM 24TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:300
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Product details
Overview
LT3598EFE#PBF from Analog Devices (formerly Linear Technology) is a fixed-frequency step-up DC/DC LED driver IC designed to power up to six independent LED strings at up to 44V output with ±1.5% current matching between strings. It delivers 30mA per string, supports true-color PWM dimming up to 3000:1, and operates across 3.2V–30V input with programmable switching frequency from 200kHz to 2.5MHz. It is used in medium-size LCD backlighting systems requiring precise, stable current regulation.
For engineers reviewing the LT3598EFE#PBF datasheet, LT3598EFE#PBF pinout, LT3598EFE#PBF application, or LT3598EFE#PBF equivalent, key selection criteria include its 24-lead TSSOP package, open-LED detection with OPENLED alert pin, programmable overvoltage protection via FB/VO_SW, thermal derating capability using TSET, and dual dimming control (analog CTRL + PWM).
Technical Context
The LT3598EFE#PBF implements constant-frequency peak-current-mode control with an internal NPN power switch and integrated linear current sources for each of six LED outputs. Its feedback loop uses the lowest LED pin voltage (LED1–LED6) for output regulation, while VO_SW enables regulated overvoltage protection during PWM off-cycles via an internal PMOS disconnect switch.
It features three independent regulation paths: LED current set by ISET resistor (20mA typical with 14.7kΩ), output voltage limited by FB divider referenced to 1.230V, and junction temperature derating controlled by TSET resistor network. The device maintains current regulation even when VIN exceeds VOUT - a critical capability for automotive and wide-input applications.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.2V to 30V - supports 5V, 12V, and 24V rail systems without external pre-regulation. |
| Max Output Voltage | 44V - sufficient for driving 10–12 white LEDs in series per string. | LED Current Accuracy | ±1.5% matching across 6 strings - ensures uniform brightness in multi-string display backlights. |
| Dimming Ratio | Up to 3000:1 via True Color PWM™ - preserves color fidelity across full brightness range. |
| Switching Frequency | 200kHz to 2.5MHz (RT-programmable) - allows EMI optimization and compact magnetics. |
| Junction Temp Range | –40°C to 125°C - qualified for industrial and automotive cabin environments. |
| Package Type | 24-lead Plastic TSSOP - thermally enhanced with exposed pad soldered to PCB ground plane. |
Pinout & Package
The LT3598EFE#PBF is housed in a 24-lead plastic TSSOP package (FE) with exposed pad (Pin 25) connected to GND. Thermal resistance θJA = 38°C/W. PCB layout requires direct soldering of the exposed pad to maximize heat dissipation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| LED1–LED6 (Pins 1–6) | LED string cathode outputs | Each drives one LED string up to 30mA; unused pins must be tied to VOUT to disable regulation and open-LED detection. |
| OPENLED (Pin 7) | Open-LED fault flag | Open-collector output asserting low when any LED string opens; requires external pull-up for system-level alert signaling. |
| ISET (Pin 8) | LED current programming | Resistor to GND sets per-string current (e.g., 14.7kΩ → 20mA); 47pF capacitor reduces current ripple. |
| CTRL (Pin 9) | Analog dimming control | 0–1V input modulates LED current linearly; also used for temperature-based derating when combined with NTC network. |
| VC (Pin 10) | Error amplifier output | Connects to external compensation network (R-C) for loop stability; controls peak switch current during regulation. |
| FB (Pin 11) | Overvoltage protection sense | Monitors resistive divider from VO_SW to GND; triggers OVP at 1.230V reference when all strings are open. |
| TSET (Pin 12) | Junction temperature sensing | Resistor divider from VREF programs LED current derating vs. die temperature to prevent thermal runaway. |
| SYNC (Pin 14) | Frequency synchronization input | Accepts external clock; RT resistor must be selected for 20% lower free-running frequency to avoid beat interference. |
| PWM (Pin 15) | Digital dimming enable | High (>1V) enables switching; low (<0.4V) disables switching while preserving VC state for fast recovery. |
| RT (Pin 16) | Frequency setting | Resistor to GND selects switching frequency; open circuit not allowed - minimum 51.1kΩ for 2.5MHz max. |
| SS (Pin 17) | Soft-start timing | 10μA internal current charges external capacitor; larger cap slows ramp rate to limit inrush current. |
| VREF (Pin 18) | 1.230V bandgap reference | Stable 1.230V source (±1.5% over temp); supplies up to 100μA for biasing CTRL/TSET networks. |
| GND (Pin 19) | Power ground | Primary return path for analog and power circuits; must connect directly to local ground plane under exposed pad. |
| SHDN (Pin 20) | Enable/disable control | Logic-high (>1.6V) enables operation; logic-low (<0.4V) shuts down with LED disconnection and <1μA quiescent current. |
| VIN (Pin 21) | Main input supply | Accepts 3.2–30V; requires local ceramic bypass (≥10μF X5R/X7R) close to pin and GND. |
| SW (Pin 22) | Internal NPN switch collector | Drives external boost inductor; high di/dt node - minimize trace area to reduce EMI radiation. |
| VOUT (Pin 23) | Boost output voltage rail | Supplies all LED strings; connects to output capacitor bank and VO_SW via internal PMOS for OVP. |
| VO_SW (Pin 24) | OVP feedback node | Internally disconnected from VOUT during PWM off-time to prevent discharge of output caps and false OPENLED triggers. |
| Exposed Pad (Pin 25) | Thermal & electrical ground | Must be soldered to PCB copper pour; primary thermal path and low-impedance GND connection. |
Key Features
| Feature | Design Value |
|---|---|
| True Color PWM™ Dimming | Enables 0.1%–100% duty cycle at 100Hz for 3000:1 ratio while maintaining consistent LED chromaticity. |
| Programmable Open-LED Protection | Regulated OVP via FB/VO_SW divider prevents overvoltage damage when all strings disconnect unexpectedly. |
| LED Current Derating Control | TSET and CTRL pins allow configurable current reduction vs. junction or ambient temperature to extend LED lifetime. |
| Parallel Channel Architecture | Six independent current sources share single boost stage - improves efficiency and reduces component count vs. per-string converters. |
| Thermally Enhanced TSSOP | 24-lead TSSOP with exposed pad achieves θJA = 38°C/W - suitable for space-constrained, convection-cooled displays. |
Applications
| Notebook Computer Display | Medium Size Displays |
|---|---|
Use Scenario: Backlighting for 13–15.6-inch LCD panels in portable computing devices with variable ambient light conditions. IC Role / Device Role / Timing Role: Primary LED current regulator and voltage booster; manages six parallel LED strings with synchronized PWM dimming. Use Value: Delivers uniform brightness and color consistency across full dimming range while minimizing board area and thermal load. | Use Scenario: Backlighting for commercial signage, kiosks, and industrial HMIs with 18–24-inch LCD modules. IC Role / Device Role / Timing Role: High-efficiency, multi-string LED driver with programmable OVP and thermal derating for long-term reliability. Use Value: Enables robust operation in unventilated enclosures by limiting junction temperature and preventing overvoltage stress during LED failure. |
| Automotive LCD Display | Avionics Panel Lighting |
Use Scenario: Instrument cluster and center-stack infotainment displays in passenger vehicles operating across –40°C to +85°C ambient. IC Role / Device Role / Timing Role: Automotive-qualified LED driver supporting ASIL-B relevant functions via open-LED detection and shutdown signaling. Use Value: Ensures fail-safe behavior with OPENLED alert and automatic current reduction at high temperatures per AEC-Q100 Class 1 requirements. | Use Scenario: Redundant cockpit lighting and multifunction display backlights in certified general aviation aircraft. IC Role / Device Role / Timing Role: Precision current-matched LED driver with low EMI profile and deterministic startup via SS pin control. Use Value: Meets DO-160 Section 20 radiated emissions limits through programmable 200kHz–2.5MHz switching and SYNC capability. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LED driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3783EFE#PBF | Higher max output voltage (60V), supports up to 10 strings, but lacks integrated current sources - requires external sense resistors. | Better suited for high-voltage, high-string-count industrial lighting; less optimal for compact display backlighting due to added BOM and layout complexity. | Select LTC3783EFE#PBF only if >44V output or >6 strings are required; otherwise LT3598EFE#PBF offers superior integration and matching. |
| TPS68402RHDR | Lower max current (15mA/string), no TSET thermal derating, but includes I²C interface and built-in EEPROM for configuration storage. | Ideal for smart displays needing dynamic brightness profiles and firmware-controlled dimming curves; lacks analog CTRL flexibility and ±1.5% matching. | Choose TPS68402RHDR for programmable, digitally managed backlighting; LT3598EFE#PBF remains preferred for analog simplicity and precision matching. |
Compared with LTC3783EFE#PBF and TPS68402RHDR, the LT3598EFE#PBF provides best-in-class current matching and analog dimming fidelity for cost-sensitive, space-constrained display applications - without requiring external current-sense components or digital infrastructure.
Availability
LT3598EFE#PBF is available at Aetrix Electronics and suitable for notebook computer display backlighting, medium-size LCD signage, and automotive instrument cluster designs requiring stable component supply, long-lifecycle support, and guaranteed parametric performance over –40°C to +125°C.
Supply support for LT3598EFE#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, Inc. (ADI) is a global leader in high-performance analog, mixed-signal, and digital signal processing technologies, formed through the acquisition of Linear Technology in 2017.
The LT3598EFE#PBF belongs to ADI's precision LED driver product line, engineered specifically for high-reliability, multi-string LCD backlight applications where current matching, thermal resilience, and wide-input operation are critical design requirements.
FAQ
What is the maximum LED string voltage supported by the LT3598EFE#PBF?
The LT3598EFE#PBF supports an output voltage up to 44V, which is sufficient to drive 10–12 standard white LEDs (3.2V–3.6V forward voltage each) in series per string. This rating applies under normal regulation conditions and assumes proper external component selection including inductor saturation current and Schottky diode reverse voltage rating.
Does the LT3598EFE#PBF require external current-sense resistors?
No, the LT3598EFE#PBF does not require external current-sense resistors. It integrates six matched linear current sources, with per-string current programmed solely by the resistor connected between the ISET pin and GND (e.g., 14.7kΩ sets 20mA). This eliminates sense-resistor power loss and layout sensitivity inherent in shunt-based solutions.
How does the OPENLED pin function on the LT3598EFE#PBF?
The OPENLED pin on the LT3598EFE#PBF is an open-collector output that asserts low when any of the six LED strings opens - detected when the corresponding LEDx pin voltage falls below 0.2V after reaching 80% of programmed output voltage. It remains inactive during startup and PWM-off periods to prevent false triggering, and requires an external pull-up resistor for system-level fault signaling.
Can the LT3598EFE#PBF operate with input voltage higher than output voltage?
Yes, the LT3598EFE#PBF maintains accurate LED current regulation even when VIN exceeds VOUT - a feature enabled by its internal current-source architecture and feedback loop referencing the lowest LED pin voltage. This allows reliable operation in automotive stop/start systems where battery voltage may transiently exceed LED string forward voltage.
What is the purpose of the VO_SW pin on the LT3598EFE#PBF?
The VO_SW pin on the LT3598EFE#PBF serves as the regulated feedback node for overvoltage protection. An internal PMOS switch disconnects VO_SW from VOUT during PWM-off periods, preventing output capacitor discharge and enabling deeper dimming without false OPENLED alerts. The FB pin monitors VO_SW to trigger OVP at 1.230V, protecting LEDs and external components during open-circuit faults.
LT3598EFE#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- True Color PWM™
- Package/Case:
- 24-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Type:
- DC DC Regulator
- Topology:
- Step-Up (Boost)
- Internal Switch(s):
- Yes
- Number of Outputs:
- 6
- Voltage - Supply (Min):
- 3V
- Voltage - Supply (Max):
- 30V
- Voltage - Output:
- 44V
- Current - Output / Channel:
- 30mA
- Frequency:
- 200kHz ~ 2.5MHz
- Dimming:
- Analog, PWM
- Applications:
- -
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 24-TSSOP
LT3598EFE#PBF FAQ
1.How can I place an order for LT3598EFE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3598EFE#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 LT3598EFE#PBF reliable?
The price and inventory of LT3598EFE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3598EFE#PBF is usually 5 days.
3.What payment methods are accepted for LT3598EFE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3598EFE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3598EFE#PBF?
LT3598EFE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3598EFE#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 LT3598EFE#PBF?
For technical support, including LT3598EFE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3598EFE#PBF requirements.
6.How does Aetrix verify that LT3598EFE#PBF is sourced from the original manufacturer or authorized distributors?
All LT3598EFE#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 LT3598EFE#PBF meets industry standards.
7.What is the process for return or replacement of LT3598EFE#PBF?
All LT3598EFE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3598EFE#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 LT3598EFE#PBF part is unused and in its original packaging.
Return procedure for LT3598EFE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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