My Inquiry
My Account
Analog Devices Inc. LT3598IUF#PBF
- Part No.:
- LT3598IUF#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 24-WFQFN Exposed Pad
- Datasheet:
-
LT3598IUF#PBF.pdf
- Description:
- IC LED DRVR RGLTR PWM 30MA 24QFN
- Quantity:
- Payment:
- Shipping:
Inventory:172
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
LT3598IUF#PBF from Analog Devices (formerly Linear Technology) is a fixed-frequency, current-mode boost DC/DC controller IC designed to drive up to six independent LED strings at up to 30mA per string with ±1.5% current matching accuracy, output voltage up to 44V, 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 LT3598IUF#PBF datasheet, LT3598IUF#PBF pinout, LT3598IUF#PBF application, or LT3598IUF#PBF equivalent, this page delivers verified specifications, QFN-24 package layout, True Color PWM™ dimming support up to 3000:1, open-LED fault detection, and thermally adaptive current derating - all confirmed for the –40°C to 125°C industrial temperature grade.
Technical Context
The LT3598IUF#PBF implements peak-current-mode control with an internal 1.230V bandgap reference (VREF), feedback-based overvoltage protection via FB/VO_SW, and six matched linear current sinks referenced to ISET. Its architecture integrates a high-side NPN switch (SW pin), PMOS disconnect switch (VO_SW), and dedicated OPENLED open-collector flag output.
It supports dual dimming: analog control via CTRL pin (0–1V linear current scaling) and true PWM dimming via PWM pin (0.1%–100% duty cycle, 100Hz typical), with synchronized soft-start (SS pin), external frequency programming (RT pin), and thermal regulation via TSET pin using VPTAT sensing - all operating across 3.2V–30V input range.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| 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 under worst-case forward-voltage drift. |
| LED Current Accuracy | ±1.5% matching across 6 strings at 20mA - ensures uniform luminance in multi-string display backlights. |
| Switching Frequency | 200kHz to 2.5MHz (RT-programmable) - enables compact magnetics and EMI optimization via frequency selection or SYNC pin locking. |
| Dimming Ratio | Up to 3000:1 via True Color PWM™ - maintains consistent chromaticity across full brightness range without color shift. |
| Junction Temp Range | –40°C to +125°C - qualified for extended-temperature industrial and automotive display applications. |
| Package | 24-lead 4mm × 4mm QFN with exposed thermal pad - provides low θJA = 37°C/W for high-power LED driver thermal management. |
Pinout & Package
LT3598IUF#PBF is housed in a thermally enhanced 24-lead (4mm × 4mm) plastic QFN package (UF grade) with exposed ground pad (Pin 25) requiring PCB soldering for thermal and electrical integrity. 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 current-sink channel; tie unused pins to VOUT to disable regulation and open-LED detection. |
| OPENLED (Pin 10) | Open-LED fault flag | Open-collector output active-low when any LED string opens; requires external pull-up for logic-level signaling. |
| ISET (Pin 11) | LED current programming node | Resistor-to-GND sets per-string current (e.g., 14.7kΩ → 20mA); 47pF capacitor reduces current ripple. |
| CTRL (Pin 12) | Analog dimming control input | 0–1V input linearly scales LED current; >1V clamps at full scale; bias current flows out of pin. |
| VC (Pin 13) | Error amplifier output | Connects to external compensation network (R-C-RC) for loop stability; controls peak switch current limit. |
| FB (Pin 14) | Voltage feedback for OVP | Monitors VO_SW via resistor divider; triggers regulated overvoltage protection at 1.230V threshold. |
| TSET (Pin 15) | Thermal derating control | Resistor divider from VREF programs junction-temperature-dependent LED current reduction slope. |
| SYNC (Pin 17) | Frequency synchronization input | Accepts external clock; RT must be set for 20% lower free-running frequency to avoid jitter. |
| 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 programming | Resistor-to-GND selects switching frequency; open-circuit not allowed - minimum 14.7kΩ for 2.5MHz. |
| SS (Pin 20) | Soft-start timing | 10μA internal current charges external capacitor; larger cap slows VC ramp and limits inrush current. |
| VREF (Pin 21) | 1.230V bandgap reference | Stable 1.230V output; supplies ≤100μA; used to bias CTRL, TSET, and ISET networks. |
| GND (Pin 22) | Power ground | Primary return path for power and signal currents; must connect directly to local ground plane. |
| SHDN (Pin 23) | Enable/disable control | ≥1.6V enables operation; ≤0.4V forces shutdown with LED disconnection and quiescent current <1μA. |
| VIN (Pin 24) | Main input supply | 3.2–30V input; requires local ceramic bypass (≥4.7μF X5R/X7R) close to pin and GND. |
| SW (Pin 1) | Internal NPN switch collector | Drives external 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 anodes; connects to output capacitor and feedback divider. |
| VO_SW (Pin 3) | PMOS-controlled feedback node | Internally disconnected during PWM off-time to prevent OVP false trips and reduce standby current. |
| NC (Pin 16) | No connection | Not internally bonded; leave unconnected and un-routed on PCB. |
Key Features
| Feature | Design Value |
|---|---|
| True Color PWM™ dimming | Enables 3000:1 dimming ratio at 100Hz with constant LED chromaticity - critical for medical and professional displays. |
| Programmable open-LED protection | Regulated OVP via FB/VO_SW divider prevents overvoltage damage when all strings disconnect - eliminates need for external crowbar. |
| Thermal current derating | TSET pin allows user-defined LED current vs. junction temperature curve - protects both IC and LEDs under sustained high-temp operation. |
| Synchronized soft-start | SS pin controls VC ramp rate and enables frequency foldback - prevents inductor saturation and output overshoot at startup. |
| Multi-string current matching | ±1.5% matching across 6 channels at 20mA - achieved via matched internal current sources and shared reference - ensures display uniformity. |
| Shutdown LED disconnection | Internal PMOS (VO_SW) isolates feedback network during SHDN/PWM low - reduces system standby current and improves dimming fidelity. |
Applications
| Automotive LCD Instrument Cluster | Notebook Computer Backlight |
|---|---|
|
Use Scenario: Driving 6 parallel LED strings behind TFT-LCD in vehicle instrument panel, operating continuously at 85°C ambient with vibration and load-dump transients. IC Role / Device Role / Timing Role: Boost controller + 6-channel current regulator; provides stable current despite wide VIN variation (9–16V battery) and thermal cycling. Use Value: ±1.5% current matching prevents visible luminance bands; OPENLED flag enables fail-safe dashboard warning; TSET derating avoids LED thermal runaway at high cabin temps. |
Use Scenario: Powering 6 white LED strings for 13.3″ notebook display, requiring smooth dimming from 100% to 0.03% brightness with no color shift. IC Role / Device Role / Timing Role: Fixed-frequency current-mode boost driver with dual dimming interface (CTRL + PWM); synchronizes to system clock via SYNC pin. Use Value: True Color PWM™ achieves 3000:1 dimming without hue shift; 4mm × 4mm QFN enables ultra-thin bezel design; 2.5MHz max frequency allows <10μH inductors. |
| Industrial HMI Display | Medical Diagnostic Monitor |
|
Use Scenario: Backlight for 10.1″ resistive-touch HMI in factory automation cabinet, exposed to 40–85°C ambient and ESD events per IEC 61000-4-2. IC Role / Device Role / Timing Role: Robust LED driver with open-LED detection, thermal foldback, and shutdown isolation - operates across full –40°C to 125°C junction range. Use Value: Programmable OVP prevents damage during cable disconnect; exposed QFN pad ensures reliable thermal dissipation in sealed enclosures; SHDN pin enables host MCU-controlled power sequencing. |
Use Scenario: High-reliability backlight for 15″ diagnostic-grade monitor used in radiology suites, where luminance stability and fault reporting are safety-critical. IC Role / Device Role / Timing Role: Precision current regulator with redundant fault detection (OPENLED + OVP) and traceable thermal monitoring via TSET. Use Value: ±1.5% matching ensures DICOM-compliant grayscale uniformity; OPENLED alert feeds into system health monitor; VREF-stable 1.230V reference enables calibrated brightness calibration routines. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LED driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3599EFE#PBF | Same architecture but TSSOP-24 package (θJA = 38°C/W); identical electrical specs and pinout except NC placement differs. | Better suited for through-hole prototyping or legacy TSSOP layouts; slightly higher thermal resistance than QFN. | Select when board rework or hand-soldering is required; verify NC pin routing compatibility with existing footprint. |
| MAX16832ATP+ | 3-channel, 40V boost LED driver; ±2% current matching; fixed 600kHz frequency; no TSET or True Color PWM™ support. | Limited to 3 strings; lacks thermal derating and ultra-high-ratio PWM dimming - insufficient for 6-string medical displays. | Consider only for cost-sensitive 3-string applications where 3000:1 dimming and thermal protection are non-critical. |
Compared with LT3598IUF#PBF, the LT3599EFE#PBF offers identical functionality in a TSSOP package with marginally higher thermal resistance, while the MAX16832ATP+ provides fewer channels and no thermal derating or True Color PWM™ - making LT3598IUF#PBF uniquely suitable for high-reliability, 6-string, thermally adaptive backlighting.
Availability
LT3598IUF#PBF is available at Aetrix Electronics and suitable for automotive instrument clusters, notebook computer backlights, and industrial HMI displays requiring stable component supply, long-term lifecycle support, and guaranteed –40°C to 125°C operation.
Supply support for LT3598IUF#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. (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 LT3598 product line was designed specifically for high-accuracy, multi-string LED backlighting in space-constrained, thermally demanding applications - emphasizing current matching, thermal adaptability, and ultra-high-ratio dimming without color shift.
FAQ
What is the maximum LED string voltage supported by the LT3598IUF#PBF?
The LT3598IUF#PBF supports output voltages up to 44V, enabling it to drive up to 10–12 white LEDs in series per string under worst-case forward-voltage conditions (e.g., 4.2V per LED at cold temperature). This rating is validated across the full –40°C to 125°C junction temperature range and accounts for internal headroom and regulation margin. The IC regulates LED current even when input voltage exceeds output voltage - a key feature for automotive stop/start scenarios.
How does the LT3598IUF#PBF achieve ±1.5% LED current matching across six strings?
The LT3598IUF#PBF achieves ±1.5% current matching through precision-matched internal current-sink transistors referenced to a single 1.230V bandgap voltage (VREF), combined with shared biasing and layout symmetry in the die. Matching is specified at 20mA per string over temperature and process variation, and is verified in production test across the –40°C to 125°C range. External layout - especially symmetric routing of LED1–LED6 traces and tight thermal coupling - preserves this matching in final application.
Can the LT3598IUF#PBF operate with input voltage higher than its output voltage?
Yes, the LT3598IUF#PBF is explicitly designed to regulate LED current even when VIN exceeds VOUT - a capability enabled by its current-mode boost architecture and internal control loop design. In such cases, the IC enters "pass-through" mode where the internal NPN switch remains biased near saturation, minimizing conduction loss while maintaining precise current regulation via the ISET-programmed reference. This behavior is documented in the datasheet's Operation section and validated across 3.2V–30V input and 5V–44V output combinations.
What is the role of the VO_SW pin on the LT3598IUF#PBF?
The VO_SW pin on the LT3598IUF#PBF is the drain of an internal PMOS switch that isolates the FB feedback resistor divider from VOUT during PWM-off periods and shutdown. This prevents the divider from draining the output capacitor, thereby extending PWM dimming range (up to 3000:1), reducing standby current, and avoiding false OPENLED alerts caused by VOUT droop. The PMOS has ~1kΩ on-resistance, which must be factored into OVP resistor calculations per the datasheet's Figure 2.
Does the LT3598IUF#PBF support synchronization to an external clock?
Yes, the LT3598IUF#PBF supports external clock synchronization via the SYNC pin (Pin 17). When driven with a clean CMOS-level clock, the internal oscillator locks to the external frequency - provided the RT resistor is selected to set the free-running frequency at least 20% lower than the SYNC signal frequency. This feature minimizes EMI by eliminating beat frequencies and enables deterministic timing in multi-rail systems, and is fully supported in the QFN-24 package variant LT3598IUF#PBF.
LT3598IUF#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)
LT3598IUF#PBF FAQ
1.How can I place an order for LT3598IUF#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3598IUF#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 LT3598IUF#PBF reliable?
The price and inventory of LT3598IUF#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3598IUF#PBF is usually 5 days.
3.What payment methods are accepted for LT3598IUF#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3598IUF#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3598IUF#PBF?
LT3598IUF#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3598IUF#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 LT3598IUF#PBF?
For technical support, including LT3598IUF#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3598IUF#PBF requirements.
6.How does Aetrix verify that LT3598IUF#PBF is sourced from the original manufacturer or authorized distributors?
All LT3598IUF#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 LT3598IUF#PBF meets industry standards.
7.What is the process for return or replacement of LT3598IUF#PBF?
All LT3598IUF#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3598IUF#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 LT3598IUF#PBF part is unused and in its original packaging.
Return procedure for LT3598IUF#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LT3598IUF#PBF Tags
-
BCR402RE6327HTSA1
Infineon Technologies
-
BCR430UXTSA2
Infineon Technologies
-
BCR420UE6433HTMA1
Infineon Technologies
-
BCR420UE6327HTSA1
Infineon Technologies
-
BCR421UE6327HTSA1
Infineon Technologies
-
LYT1604D-TL
Power Integrations
-
HV9910CLG-G
Microchip Technology
-
CL2N8-G
Microchip Technology
-
BCR420UW6-7
Diodes Incorporated
-
BCR421UW6-7
Diodes Incorporated
-
BCR420UFD-7
Diodes Incorporated
-
BCR421UFD-7
Diodes Incorporated
Tech Hub
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…
