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Analog Devices Inc. LT3598IFE#PBF
- Part No.:
- LT3598IFE#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 24-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LT3598IFE#PBF.pdf
- Description:
- IC LED DRV RGLTR PWM 24TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:101
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Product details
Overview
LT3598IFE#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 30mA per string with ±1.5% current matching accuracy, 44V maximum output voltage, and programmable switching frequency from 200kHz to 2.5MHz - used in medium-size LCD backlighting systems requiring precise brightness control and thermal robustness.
For engineers reviewing the LT3598IFE#PBF datasheet, LT3598IFE#PBF pinout, LT3598IFE#PBF application, or LT3598IFE#PBF equivalent, this page delivers verified technical context, validated pin functions, confirmed thermal derating behavior, real-world dimming performance (3000:1 True Color PWM™), and accurate package mapping for the 24-lead TSSOP variant.
Technical Context
The LT3598IFE#PBF implements constant-frequency peak-current-mode control with an internal NPN power switch and six matched linear current sinks. It regulates LED current via ISET-programmed reference and maintains output voltage by monitoring the lowest LEDx pin voltage among active strings, enabling stable operation even when input voltage exceeds output voltage (VIN > VOUT).
Its dual-dimming architecture supports analog control via CTRL pin (0–1V linear scaling) and high-ratio PWM dimming (0.1%–100% duty cycle at 100Hz), while integrated features include programmable overvoltage protection using FB/VO_SW, OPENLED open-circuit detection with active-low flag, and junction-temperature-based LED current derating via TSET pin with external resistor divider.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| LED String Count | 6 independent strings, each configurable up to 30mA - enables full-array local dimming in medium-format displays. |
| Current Matching Accuracy | ±1.5% across all strings at 20mA - ensures uniform luminance without visible banding in multi-string backlight systems. |
| Input Voltage Range | 3.2V to 30V - supports wide-input industrial and automotive supply rails without pre-regulation. |
| Max Output Voltage | 44V - sufficient to drive 10+ white LEDs in series per string (≈3.8V/V) under worst-case forward-voltage conditions. |
| Switching Frequency Range | 200kHz to 2.5MHz (RT-programmable) - allows EMI optimization and compact magnetics selection (e.g., 4.7μH–22μH inductors). |
| Dimming Ratio (PWM) | Up to 3000:1 (True Color PWM™) - preserves chromaticity across full brightness range in display applications. |
| Junction Temp Range | –40°C to 125°C - qualified for extended-temperature industrial and automotive LCD modules. |
| Package Type | 24-lead plastic TSSOP (FE package), exposed pad soldered to PCB - provides θJA = 38°C/W thermal resistance for reliable power dissipation. |
Pinout & Package
LT3598IFE#PBF is housed in a thermally enhanced 24-lead plastic TSSOP (FE package) with exposed pad (Pin 25) connected to PGND. The package measures standard TSSOP footprint (7.8mm × 4.4mm) and requires soldering of the exposed pad to PCB ground plane for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| LED1–LED6 (Pins 1–6) | LED string cathode outputs | Each drives one LED string; tie unused pins to VOUT to disable regulation and OPENLED detection for that string. |
| OPENLED (Pin 7) | Open-circuit flag output | Active-low open-collector signal indicating any LED string open condition; requires external pull-up resistor. |
| ISET (Pin 8) | LED current programming node | Resistor to GND sets per-string current (e.g., 14.7kΩ → 20mA); 47pF capacitor reduces current ripple. |
| CTRL (Pin 9) | Analog dimming control input | 0–1V input linearly scales LED current; above 1V clamps at full current; used for temperature derating via NTC network. |
| VC (Pin 10) | Error amplifier output | Connects to external compensation network; controls peak switch current during regulation and soft-start. |
| FB (Pin 11) | Overvoltage protection feedback | Monitors VO_SW via resistor divider; triggers regulated OVP at 1.230V threshold when all strings are open. |
| TSET (Pin 12) | Junction temperature sensing input | External resistor divider from VREF programs LED current derating vs. die temperature - protects IC and LEDs. |
| NC (Pin 13) | No connection | Not internally bonded; must remain unconnected. |
| SYNC (Pin 14) | Frequency synchronization input | Accepts external clock; RT must be set for 20% lower free-running frequency to avoid jitter or lock failure. |
| PWM (Pin 15) | Digital dimming enable/disable | High (>1V) enables switching; low (<0.4V) disables switching and holds VC voltage - enables fast, clean PWM dimming. |
| RT (Pin 16) | Frequency setting resistor node | Resistor to GND programs switching frequency; must not float - values from 14.7kΩ (2.5MHz) to 309kΩ (171kHz). |
| SS (Pin 17) | Soft-start capacitor node | 10μA internal current charges external capacitor; larger cap slows startup and reduces inrush stress on input supply. |
| VREF (Pin 18) | 1.230V bandgap reference | Stable 1.230V output; supplies ≤100μA; used to bias CTRL, TSET, and ISET networks. |
| GND (Pin 19) | Power ground | Primary return path for internal circuits and power switch; must connect directly to local ground plane. |
| SHDN (Pin 20) | Enable/disable control | ≥1.6V enables device; ≤0.4V forces shutdown with LED disconnection and VC discharge hold. |
| VIN (Pin 21) | Main input supply | 3.2V–30V input; requires local ceramic bypass capacitor (e.g., 2.2μF X5R) close to pin. |
| 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 | Delivers regulated high-voltage supply to all LED anodes; connects to external Schottky rectifier and output capacitor. |
| VO_SW (Pin 24) | PMOS-controlled feedback node | Internal PMOS disconnects FB divider from VOUT during PWM off-time - prevents false OPENLED trips and improves dimming ratio. |
| Exposed Pad (Pin 25) | PGND thermal/electrical connection | Mandatory solder connection to PCB ground plane; critical for thermal performance (θJA = 38°C/W) and noise immunity. |
Key Features
| Feature | Design Value |
|---|---|
| True Color PWM™ dimming | 3000:1 dimming ratio with constant chromaticity - eliminates color shift in display backlighting across full brightness range. |
| Programmable LED current derating | Configurable current reduction vs. junction temperature via TSET pin - protects IC and LEDs under sustained high-ambient conditions. |
| Regulated open-LED protection | OVP activated only when all six strings are open, using FB/VO_SW feedback - avoids false trips during single-string faults. |
| Thermally enhanced TSSOP | 24-lead FE package with exposed pad (θJA = 38°C/W) - enables 6-string operation at full 30mA without forced air or heatsink. |
| Independent LED string disable | Unused LEDx pins tied to VOUT remove strings from regulation loop and OPENLED monitoring - simplifies design reuse across panel sizes. |
| Synchronizable switching frequency | SYNC pin accepts external clock; RT resistor set 20% below sync frequency - eliminates beat frequencies in multi-converter systems. |
Applications
| Notebook Computer Display | Medium Size Displays |
|---|---|
|
Use Scenario: Backlighting for 13–15.6-inch notebook LCD panels with edge-lit or direct-lit LED arrays. IC Role / Device Role / Timing Role: Primary LED driver IC providing six-channel current regulation, synchronized PWM dimming, and thermal derating for long-term reliability. Use Value: ±1.5% current matching eliminates vertical luminance bands; 3000:1 True Color PWM™ enables seamless brightness transitions in UI and video playback. |
Use Scenario: Backlight for commercial signage, medical monitors, and industrial HMIs (19–24 inch). IC Role / Device Role / Timing Role: High-efficiency boost LED driver supporting variable string counts and ambient-temperature-adaptive current control. Use Value: TSET-based derating extends LED lifetime at elevated cabinet temperatures; programmable OVP prevents overvoltage damage during cable disconnect events. |
| Automotive LCD Display | Industrial Control Panel |
|
Use Scenario: Instrument cluster and infotainment display backlighting in passenger vehicles (–40°C to +105°C ambient). IC Role / Device Role / Timing Role: AEC-Q200–capable LED driver delivering robust dimming, open-wire fault detection, and wide-input operation. Use Value: OPENLED flag enables diagnostic logging of LED failures; SHDN-controlled fast shutdown meets automotive safety requirements. |
Use Scenario: Operator interface backlighting in factory automation panels exposed to dust, vibration, and thermal cycling. IC Role / Device Role / Timing Role: Industrial-grade LED controller with extended temperature range, ESD-hardened pins, and latch-free fault response. Use Value: 125°C max junction rating and exposed-pad thermal design ensure continuous operation in sealed enclosures without derating. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LED driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3220EUD#PBF | Charge-pump topology (no inductor), max 36V output, 4-string, ±2% matching, fixed 1MHz switching | Better for space-constrained designs where inductor placement is impractical; limited to lower output voltages and fewer strings | Select when board area is critical and LED string count ≤4; not suitable for >40V or 6-string configurations. |
| TPS68400RHDR | Boost + linear hybrid, 6-string, ±1.2% matching, 40V max output, integrated MOSFETs, I²C interface | Offers digital control and diagnostics via I²C; higher quiescent current (120μA vs. 1μA shutdown) and different thermal profile | Choose for systems requiring telemetry, dynamic reconfiguration, or tighter matching; requires firmware integration. |
Compared with LTC3220EUD#PBF and TPS68400RHDR, the LT3598IFE#PBF delivers superior output voltage headroom (44V), proven 6-string stability in production displays, and analog-dimming simplicity - making it optimal for cost-sensitive, high-reliability medium-format backlighting where digital control is unnecessary.
Availability
LT3598IFE#PBF is available at Aetrix Electronics and suitable for notebook computer display backlighting, medium-size industrial HMIs, and automotive instrument cluster lighting requiring stable component supply, long lifecycle support, and guaranteed extended-temperature performance.
Supply support for LT3598IFE#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 precision instrumentation, industrial, automotive, and communications markets.
The LT3598IFE#PBF belongs to Linear's high-accuracy LED driver product line, engineered specifically for medium-format LCD backlighting where string matching, thermal resilience, and analog/PWM hybrid dimming are critical system requirements.
FAQ
What is the maximum LED string voltage supported by the LT3598IFE#PBF?
The LT3598IFE#PBF supports up to 44V output voltage, sufficient to drive approximately 10–12 white LEDs in series per string (assuming typical VF of 3.6–3.8V per LED at 30mA). This headroom accommodates worst-case forward-voltage variation and temperature drift across the full operating temperature range.
Does the LT3598IFE#PBF require an external Schottky diode, and what specifications are critical?
Yes, the LT3598IFE#PBF requires an external Schottky diode connected between SW and VOUT. Critical specs include reverse voltage rating exceeding the application's max VOUT (e.g., ≥50V), average current rating exceeding total LED current (e.g., ≥2A for six 30mA strings), and low reverse leakage to preserve PWM dimming ratio - diodes like SS3H9 (90V, 3A, Vishay) are validated.
How does the OPENLED function behave when only one LED string opens during operation?
When a single LED string opens, the LT3598IFE#PBF continues regulating using the remaining five strings' lowest LEDx pin voltage. OPENLED asserts only if the open string has the lowest voltage among active strings and remains below 0.2V for the specified delay - otherwise, regulation continues seamlessly without flag assertion.
Can the LT3598IFE#PBF operate with VIN greater than VOUT, and how is regulation maintained?
Yes, the LT3598IFE#PBF regulates LED current even when VIN exceeds VOUT - a key advantage over basic buck-based drivers. Regulation is maintained by the internal current-sink architecture: each LED string draws its programmed current regardless of input-output differential, with the boost converter only supplying the required overhead voltage.
What is the purpose of the VO_SW pin on the LT3598IFE#PBF, and how does it improve performance?
The VO_SW pin connects to an internal PMOS switch between VOUT and the FB resistor divider. During PWM off-time, the PMOS disconnects the divider, preventing output capacitor discharge through the feedback network - this enables deeper dimming (down to 0.1% duty cycle) and avoids false OPENLED assertions caused by VOUT droop.
LT3598IFE#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
LT3598IFE#PBF FAQ
1.How can I place an order for LT3598IFE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3598IFE#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 LT3598IFE#PBF reliable?
The price and inventory of LT3598IFE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3598IFE#PBF is usually 5 days.
3.What payment methods are accepted for LT3598IFE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3598IFE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3598IFE#PBF?
LT3598IFE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3598IFE#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 LT3598IFE#PBF?
For technical support, including LT3598IFE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3598IFE#PBF requirements.
6.How does Aetrix verify that LT3598IFE#PBF is sourced from the original manufacturer or authorized distributors?
All LT3598IFE#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 LT3598IFE#PBF meets industry standards.
7.What is the process for return or replacement of LT3598IFE#PBF?
All LT3598IFE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3598IFE#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 LT3598IFE#PBF part is unused and in its original packaging.
Return procedure for LT3598IFE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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