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Analog Devices Inc. LT3598EUF#PBF
- Part No.:
- LT3598EUF#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 24-WFQFN Exposed Pad
- Datasheet:
-
LT3598EUF#PBF.pdf
- Description:
- IC LED DRVR RGLTR PWM 30MA 24QFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,190
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Product details
Overview
LT3598EUF#PBF from Analog Devices (formerly Linear Technology) is a fixed-frequency boost 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, supporting output voltages up to 44V and input voltages from 3.2V to 30V. It enables true-color PWM dimming with up to 3000:1 ratio and integrates programmable overvoltage protection, thermal derating via TSET, and open-LED detection - used in notebook display backlighting and automotive LCD panels.
For engineers reviewing the LT3598EUF#PBF datasheet, LT3598EUF#PBF pinout, LT3598EUF#PBF application, or LT3598EUF#PBF equivalent, key selection criteria include its 24-pin 4mm × 4mm QFN package, 200kHz–2.5MHz adjustable switching frequency, ±1.5% LED current matching across six channels, integrated OPENLED alert, and dual dimming support (analog CTRL + PWM).
Technical Context
The LT3598EUF#PBF implements constant-frequency peak-current-mode control with an internal NPN power switch and six matched linear current sinks. Its feedback loop uses the lowest LED-string voltage (LED1–LED6) for output regulation, while VO_SW isolates the FB divider during PWM off-time to preserve dimming range and prevent false OPENLED alerts.
It features three independent regulation paths: current-loop control via ISET resistor (20mA typical), overvoltage protection via FB/VO_SW resistor divider (1.230V reference), and junction-temperature-based LED current derating via TSET pin. The VC pin serves as error amplifier output for external compensation, and SYNC allows frequency locking to an external clock 20% faster than the RT-set frequency.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.2V to 30V - supports wide-range industrial and automotive supplies without pre-regulation. |
| Max Output Voltage | 44V - sufficient to drive 10+ white LEDs in series per string (3.5V/V typical). |
| LED Current Accuracy | ±1.5% matching across 6 strings - ensures uniform brightness in multi-string displays. |
| Switching Frequency | 200kHz to 2.5MHz (RT-programmable) - enables compact magnetics and EMI optimization. |
| Dimming Ratio | Up to 3000:1 (True Color PWM™) - maintains consistent chromaticity across full brightness range. |
| Junction Temp Range | –40°C to 125°C - qualified for automotive cabin and industrial ambient environments. |
| Efficiency | 90% typical - reduces thermal load in space-constrained backlight modules. |
Pinout & Package
LT3598EUF#PBF is housed in a thermally enhanced 24-lead (4mm × 4mm) plastic QFN package with exposed pad (Pin 25) soldered to PCB ground for optimal thermal dissipation (θJA = 37°C/W). Pin numbering follows top-view standard with Pin 1 at bottom-left corner.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| LED1–LED6 (Pins 4–9) | 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 10) | Open-LED flag output | Open-collector alert signal activated when any LED string opens; requires external pull-up for logic-level signaling. |
| ISET (Pin 11) | LED current programming input | Resistor to GND sets per-string current (e.g., 14.7kΩ → 20mA); 47pF capacitor reduces current ripple. |
| CTRL (Pin 12) | Analog dimming control | 0–1V input linearly scales LED current; >1V clamps at full scale; supports temperature-based derating networks. |
| VC (Pin 13) | Error amplifier output | Drives external RC compensation network; directly controls peak switch current limit during regulation. |
| FB (Pin 14) | Overvoltage protection sense | Monitors VO_SW via resistor divider; triggers OVP at 1.230V threshold when all strings are open. |
| TSET (Pin 15) | Junction temperature sensing | Resistor divider from VREF programs LED current reduction vs. die temperature to prevent thermal runaway. |
| SYNC (Pin 17) | Frequency synchronization input | Accepts external clock; RT must be set for 20% lower free-running frequency to avoid beat interference. |
| PWM (Pin 18) | Digital dimming enable | High (>1V) enables switching; low (<0.4V) disables switching while preserving VC state for fast recovery. |
| RT (Pin 19) | Frequency setting input | Resistor to GND selects switching frequency; open-circuit not allowed - minimum 51.1kΩ for 2.5MHz. |
| SS (Pin 20) | Soft-start timing | 10μA current charges external capacitor; controls ramp rate of VC voltage and peak switch current at startup. |
| VREF (Pin 21) | 1.230V bandgap reference | Stable internal reference; supplies ≤100μA; used to bias CTRL, TSET, and FB divider networks. |
| GND (Pin 22) | Power ground | Primary return path for VIN, SW, and analog circuitry; must connect directly to local ground plane. |
| SHDN (Pin 23) | Enable/disable control | Logic-high (>1.6V) enables operation; logic-low (<0.4V) shuts down IC and disconnects LEDs. |
| VIN (Pin 24) | Main input supply | 3.2–30V input; requires local ceramic bypass capacitor (≥2.2μF) close to pin. |
| SW (Pin 1) | Internal NPN switch collector | Connects to boost inductor; high di/dt node - minimize trace area to reduce EMI radiation. |
| VOUT (Pin 2) | Boost output rail | Delivers regulated high-voltage supply to all LED strings; requires ≥4.7μF low-ESR ceramic output cap. |
| VO_SW (Pin 3) | PMOS-controlled feedback node | Isolates FB divider from VOUT during PWM off-time to extend dimming range and reduce shutdown current. |
| NC (Pin 16) | No connection | Not internally bonded; leave unconnected and un-routed on PCB. |
Key Features
| Feature | Design Value |
|---|---|
| Six-channel matched current sinks | ±1.5% current matching at 20mA ensures uniform luminance across multi-string displays without per-string calibration. |
| True Color PWM™ dimming | 3000:1 dimming ratio with constant LED color point maintained across entire brightness range via precise PWM-controlled current gating. |
| Programmable thermal derating | TSET pin accepts resistor network to linearly reduce LED current above user-defined junction temperature breakpoint, protecting both IC and LEDs. |
| Regulated open-LED protection | OPENLED pin asserts open-collector flag only after confirmed open condition (80% VOUT delay), preventing false triggers during transient events. |
| Output voltage limiting during shutdown | VO_SW PMOS disconnects FB divider from VOUT during SHDN/PWM low, reducing standby current and enabling safe hot-swap capability. |
Applications
| Notebook Computer Display | Medium Size Displays |
|---|---|
Use Scenario: Backlighting for 13–15.6-inch LCD panels in ultrabooks and business laptops requiring thin profile and low power consumption. IC Role / Device Role / Timing Role: Primary LED driver IC managing six parallel LED strings with synchronized PWM dimming and thermal foldback. Use Value: Enables 3000:1 contrast-adjustable backlight with ±1.5% brightness uniformity and automatic current reduction above 85°C junction temperature. | Use Scenario: Backlight for 18–24-inch commercial monitors, POS terminals, and medical display units operating in variable ambient conditions. IC Role / Device Role / Timing Role: High-accuracy multi-string LED controller with programmable OVP and open-LED fault reporting for system-level diagnostics. Use Value: Delivers stable 44V output with <1% output voltage drift over temperature, supporting long-life LED arrays without external current sensing. |
| Automotive LCD Display | Industrial HMI Panels |
Use Scenario: Instrument cluster and infotainment screen backlighting in vehicles where EMC, thermal robustness, and AEC-Q200 compliance are critical. IC Role / Device Role / Timing Role: Automotive-grade LED driver with SYNC input for EMI spread-spectrum alignment and TSET-based thermal management. Use Value: Meets ISO 11452-2 radiated immunity requirements via 2.5MHz max switching frequency and provides fail-safe OPENLED alert for ASIL-B systems. | Use Scenario: Ruggedized human-machine interface panels in factory automation, where wide input voltage (12–24V DC) and extended temperature operation are required. IC Role / Device Role / Timing Role: Industrial LED driver with 3.2–30V input range, –40°C to 125°C operation, and programmable current derating for enclosure heat buildup. Use Value: Eliminates need for external thermal sensors by integrating junction-temperature-based LED current scaling, reducing BOM count and layout complexity. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LED driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3599EUF#PBF | Same 24-pin QFN package; adds independent PWM dimming per string and higher 40mA per string capability. | Required for asymmetric dimming (e.g., side-lit vs. direct-lit zones) or higher-brightness displays needing >30mA/string. | Select LT3599EUF#PBF only if per-string PWM control or >30mA drive is needed; otherwise LT3598EUF#PBF offers lower cost and simpler layout. |
| TPS68400RHDR | TI 6-channel boost LED driver in 24-pin QFN; 2.2MHz max frequency, ±2% current matching, no TSET thermal derating pin. | Lacks integrated junction-temperature-based current scaling; requires external thermal monitoring for LED protection. | Choose TPS68400RHDR for TI ecosystem compatibility or when using existing TI power design tools; LT3598EUF#PBF preferred for thermal autonomy and tighter current matching. |
Compared with LT3599EUF#PBF and TPS68400RHDR, the LT3598EUF#PBF delivers superior current matching (±1.5% vs. ±2%), integrated thermal derating (TSET), and lower quiescent current (5mA vs. 6.5mA), making it optimal for cost-sensitive, thermally constrained display backlight designs where per-string dimming is unnecessary.
Availability
LT3598EUF#PBF is available at Aetrix Electronics and suitable for notebook display backlighting, automotive LCD instrumentation, and industrial HMI panels requiring stable component supply, long-term lifecycle support, and guaranteed lead-free compliance.
Supply support for LT3598EUF#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.
The LT3598EUF#PBF belongs to Linear's high-efficiency LED driver product line, engineered specifically for multi-string LCD backlight applications demanding precision current matching, wide dimming range, and robust thermal management in compact form factors.
FAQ
What is the maximum LED string voltage supported by the LT3598EUF#PBF?
The LT3598EUF#PBF supports a maximum output voltage of 44V, which is the upper limit for the VOUT pin and all LED1–LED6 pins. This allows driving up to 12 white LEDs (3.5V forward voltage each) in series per string under typical conditions. The device regulates current even when input voltage exceeds output voltage, enabling flexible power architecture design. Always verify actual string voltage with worst-case LED VF and temperature coefficients in your LT3598EUF#PBF application.
How does the OPENLED pin function in the LT3598EUF#PBF?
The OPENLED pin on the LT3598EUF#PBF is an open-collector output that asserts low when any of the six LED strings opens, provided the PWM signal is active and the condition persists beyond an internal delay (triggered after reaching 80% of programmed VOUT). It requires an external pull-up resistor to a valid logic supply. During startup and PWM disable, OPENLED detection is inhibited to prevent false alarms. This feature enables system-level fault reporting in displays using the LT3598EUF#PBF as the primary LED driver.
Can the LT3598EUF#PBF operate with input voltage higher than output voltage?
Yes, the LT3598EUF#PBF is explicitly designed to regulate LED current even when VIN exceeds VOUT - a key differentiator from basic boost controllers. Its internal architecture decouples current regulation from input-output voltage relationship, allowing stable 30mA operation across input ranges from 3.2V to 30V regardless of whether VOUT is 5V or 44V. This capability simplifies power supply design in systems with variable or wide-input rails feeding the LT3598EUF#PBF.
What is the purpose of the VO_SW pin on the LT3598EUF#PBF?
The VO_SW pin on the LT3598EUF#PBF is the drain of an internal PMOS switch that isolates the FB resistor divider from VOUT during PWM off-time and shutdown. This prevents the divider from discharging the output capacitor, thereby extending PWM dimming range (up to 3000:1) and reducing standby current. When designing with the LT3598EUF#PBF, the FB divider must connect to VO_SW - not VOUT - and account for the PMOS's ~1kΩ on-resistance in voltage-setting calculations.
How is LED current programmed on the LT3598EUF#PBF?
LED current per string on the LT3598EUF#PBF is primarily set by a resistor (RISET) between the ISET pin and GND, using the formula ILED ≈ 294V / RISET. For example, a 14.7kΩ resistor yields ~20mA. A 47pF capacitor on ISET reduces current ripple. Alternatively, analog dimming is achieved by applying 0–1V to the CTRL pin, which linearly scales current from 0% to 100% of the ISET-programmed value. Both methods are supported simultaneously in the LT3598EUF#PBF design.
LT3598EUF#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- True Color PWM™
- Package/Case:
- 24-WFQFN 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-QFN (4x4)
LT3598EUF#PBF FAQ
1.How can I place an order for LT3598EUF#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3598EUF#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 LT3598EUF#PBF reliable?
The price and inventory of LT3598EUF#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3598EUF#PBF is usually 5 days.
3.What payment methods are accepted for LT3598EUF#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3598EUF#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3598EUF#PBF?
LT3598EUF#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3598EUF#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 LT3598EUF#PBF?
For technical support, including LT3598EUF#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3598EUF#PBF requirements.
6.How does Aetrix verify that LT3598EUF#PBF is sourced from the original manufacturer or authorized distributors?
All LT3598EUF#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 LT3598EUF#PBF meets industry standards.
7.What is the process for return or replacement of LT3598EUF#PBF?
All LT3598EUF#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3598EUF#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 LT3598EUF#PBF part is unused and in its original packaging.
Return procedure for LT3598EUF#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LT3598EUF#PBF Tags
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BCR402RE6327HTSA1
Infineon Technologies
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BCR430UXTSA2
Infineon Technologies
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BCR420UE6433HTMA1
Infineon Technologies
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BCR420UE6327HTSA1
Infineon Technologies
-
BCR421UE6327HTSA1
Infineon Technologies
-
LYT1604D-TL
Power Integrations
-
HV9910CLG-G
Microchip Technology
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CL2N8-G
Microchip Technology
-
BCR420UW6-7
Diodes Incorporated
-
BCR421UW6-7
Diodes Incorporated
-
BCR420UFD-7
Diodes Incorporated
-
BCR421UFD-7
Diodes Incorporated
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