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Texas Instruments LM3311SQX
- Part No.:
- LM3311SQX
- Manufacturer:
- Texas Instruments
- Package:
- 24-WFQFN Exposed Pad
- Datasheet:
-
LM3311SQX.pdf
- Description:
- IC REG BOOST ADJ 2A 24WQFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,926
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Product details
Overview
LM3311SQX from Texas Instruments is a highly integrated step-up DC/DC converter with co-located LDO regulator, rail-to-rail operational amplifier (135mA sink/source), and gate pulse modulation (GPM) switch for TFT LCD bias generation. It delivers 2A boost output up to 20V with 0.18Ω internal NMOS switch, operates from 2.5V–7V input, and supports pin-selectable 660kHz/1.28MHz switching frequency - enabling compact, high-efficiency power solutions in portable display systems.
For engineers reviewing the LM3311SQX datasheet, LM3311SQX pinout, LM3311SQX application, or LM3311SQX equivalent, key selection considerations include its integrated GPM timing control (VFLK/VDPM interface), adjustable soft-start via external capacitor, dual feedback architecture (boost FB and LDO ADJ pins both referenced to 1.263V), and thermal shutdown with 20°C hysteresis at 145°C junction temperature.
Technical Context
The LM3311SQX implements a current-mode PWM boost controller with internal 2A/0.18Ω NMOS switch and programmable maximum duty cycle (80–91% depending on frequency). Its GPM block accepts VFLK timing signals and modulates VGHM output using an external RE resistor and CE capacitor, supporting precise TFT gate-on/off sequencing. The integrated op-amp features rail-to-rail I/O, 3.3MHz GBW, and 50V/µs slew rate - usable as buffer, comparator, or driver without external compensation.
The LDO section accepts 2.5V–7V input (LVIN), delivers adjustable output (via ADJ pin and resistor divider), maintains stability with ≥2.2µF ceramic capacitors, and exhibits 218–674mV dropout at 350mA. All functional blocks - boost, LDO, op-amp, and GPM - share common AGND/PGND connection to the exposed DAP, requiring direct thermal pad grounding per RTW0024A package layout guidelines.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Boost Output Range | Adjustable up to 20V; set by FB pin voltage (1.263V typical) and external RFB1/RFB2 divider - enables flexible TFT VPOS/VNEG rail generation. |
| Switch Current Limit | 2.0A minimum; ensures robust inductor current handling during startup and load transients without external current-sense components. |
| Switching Frequency | 660kHz or 1.28MHz selectable via FREQ pin; higher frequency allows smaller inductors/capacitors but increases switching losses. |
| LDO Dropout Voltage | 218mV typical at 350mA; enables efficient low-headroom regulation from shared system rails like 3.3V or 5V. |
| Op-Amp Output Drive | 135mA sink/source (standard version); sufficient to directly drive gate drivers, LED strings, or analog front-end circuitry without buffering. |
| GPM VGH Input Range | 5V to 30V; supports wide-range TFT panel gate supply voltages while maintaining precise VGHM timing control via RE/CE network. |
| Thermal Shutdown | Activates at 145°C junction temperature with 20°C hysteresis; protects against sustained overload or poor PCB thermal design. |
Pinout & Package
The LM3311SQX is housed in a 24-lead WQFN package (RTW0024A) with exposed thermal pad (DAP) internally connected to GND. AGND and PGND must be soldered directly to the DAP for optimal thermal performance and noise isolation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 NC | No connect | Not internally bonded; must remain unconnected on PCB. |
| 2 VGHM | GPM output | Drives gate driver supply; voltage determined by VGH, RE, and CE - used for TFT gate-on timing control. |
| 3 VFLK | TFT enable timing input | Accepts logic-level signal (0.4V/1.4V thresholds) to synchronize VGHM activation with display frame timing. |
| 4 VDPM | GPM enable control | High = enable GPM block; low = disable VGHM output - used for power sequencing and panel sleep/wake control. |
| 5 VDD | GPM reference | Sets lower VGHM clamp voltage; connect to VIN if GPM unused. |
| 6 AVIN | Op-amp analog supply | 4V–14V input; powers op-amp independently of boost/LDO supplies for noise isolation. |
| 7 OUT | Op-amp output | Rail-to-rail capable; drives loads up to 135mA with 50V/µs slew rate - suitable for active filtering or level-shifting. |
| 10 AGND | Analog ground | Common return for boost error amp, LDO, and op-amp; must tie directly to DAP and PGND under device. |
| 11 ADJ | LDO feedback | 1.263V reference node; sets LDO output voltage via external resistor divider (LVIN → ADJ → GND). |
| 14 SS | Soft-start control | External capacitor sets ramp time (TSS = CSS × 1.24V / 11µA); prevents inrush current into output caps. |
| 16 FREQ | Frequency select | AGND = 660kHz; VIN = 1.28MHz - selects trade-off between component size and efficiency. |
| 17 VIN | Boost input supply | 2.5V–7V main power input for boost converter and GPM circuits. |
| 18 SW | Boost switch node | Connects internal NMOS drain to external inductor; requires low-ESR ceramic cap to PGND. |
| 19 SHDN | Global enable | Active-low; pulls internal regulators and GPM offline with <2µA quiescent current in shutdown. |
| 20 FB | Boost feedback | 1.263V reference node; sets boost output voltage via resistor divider (VOUT → FB → GND). |
| 21 PGND | Power ground | Return for boost switch and GPM circuits; must connect to DAP and AGND under device. |
| 22 CE | GPM timing capacitor | Connects to AGND; forms RC network with RE to shape VGHM rise/fall times for clean gate pulses. |
| 23 RE | GPM timing resistor | Connects to PGND; sets VGHM slew rate and pulse width in conjunction with CE and VFLK timing. |
| 24 VGH | GPM high-voltage supply | 5V–30V input for GPM block; powers VGHM output and determines maximum gate drive voltage. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated GPM block | Eliminates need for discrete gate pulse generators; enables precise TFT panel timing control via VFLK/VDPM inputs and RE/CE programmability. |
| Adjustable soft-start | External CSS capacitor sets controlled output ramp time - prevents inrush current damage to capacitors and downstream circuitry. |
| Dual independent feedback | Separate FB (boost) and ADJ (LDO) pins both referenced to 1.263V - simplifies design of multi-rail bias supplies with shared reference accuracy. |
| Thermal and UVLO protection | Automatically disables all blocks at 145°C junction temp or below 2.4V VIN - ensures safe operation under fault conditions without external supervision. |
| Rail-to-rail op-amp | Delivers full AVIN swing at 135mA load with 3.3MHz GBW - supports high-speed analog functions such as active filtering or sensor signal conditioning. |
Applications
| TFT LCD Panel Bias Supply | Portable Display Power Management |
|---|---|
Use Scenario: Generating positive (VPOS) and negative (VNEG) bias rails for active-matrix TFT LCD panels in handheld devices. IC Role / Device Role / Timing Role: LM3311SQX acts as primary power hub - boost converter generates VPOS, LDO derives VNEG reference, op-amp buffers timing signals, and GPM precisely controls gate-on timing via VFLK/VDPM. Use Value: Single-chip integration reduces BOM count by >6 discrete components versus discrete boost + LDO + op-amp + GPM solution; 660kHz/1.28MHz flexibility optimizes inductor size vs. efficiency trade-off. | Use Scenario: Powering display subsystems in battery-powered medical monitors, industrial HMIs, and ruggedized tablets where space and thermal constraints are critical. IC Role / Device Role / Timing Role: LM3311SQX serves as intelligent display PMIC - manages input UVLO, regulates multiple rails, provides fast transient response, and sequences panel power-up/down via SHDN and VDPM. Use Value: 2.5V–7V input range accommodates single-cell Li-ion (3.0–4.2V) or dual-cell configurations; 0.18Ω RDSON and 2A switch deliver >90% efficiency at 500mA load. |
| Automotive Infotainment Displays | Industrial Control Panel Interfaces |
Use Scenario: Driving high-resolution automotive TFT displays requiring stable, low-noise VGH/VGL supplies and precise gate timing under wide temperature (-40°C to +125°C). IC Role / Device Role / Timing Role: LM3311SQX functions as display power controller - boost supplies VGH, LDO supplies VGL, op-amp conditions timing signals, and GPM synchronizes gate pulses to display controller's VFLK. Use Value: Guaranteed operation across full automotive temperature range; thermal shutdown with 20°C hysteresis prevents latch-up in enclosed dash environments. | Use Scenario: Powering monochrome or color STN/TFT displays in factory automation HMIs, PLC operator terminals, and test equipment with stringent EMI and reliability requirements. IC Role / Device Role / Timing Role: LM3311SQX operates as compact display power solution - boost generates panel bias, LDO powers controller ICs, op-amp interfaces with touch controller, and GPM handles display enable sequencing. Use Value: WQFN package with exposed DAP enables efficient heat dissipation on 2-layer PCBs; integrated protections reduce need for external supervision circuitry. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar multi-function display power management applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS65136RGTR | Single-chip TFT PMIC with dual boost + dual LDO + GPM; lacks integrated op-amp; fixed 1.2MHz switching. | Optimized for high-volume consumer panels; no analog signal conditioning capability. | Select when op-amp functionality is unnecessary and board space is extremely constrained. |
| MAX17105ETL+ | Triple-output TFT PMIC with boost + dual LDO + GPM + integrated MOSFET drivers; higher VGH support (up to 35V); no op-amp. | Targets larger industrial panels requiring higher gate drive; adds integrated level shifters and fault reporting. | Select when driving >10-inch panels with >25V VGH and requiring built-in fault diagnostics. |
Compared with TPS65136RGTR and MAX17105ETL+, the LM3311SQX uniquely integrates a rail-to-rail op-amp alongside boost, LDO, and GPM - enabling on-chip signal conditioning, active filtering, or closed-loop bias control without adding external amplifiers or layout complexity.
Availability
LM3311SQX is available at Aetrix Electronics and suitable for TFT LCD bias supplies, portable display power management, and automotive infotainment displays requiring stable component supply, extended temperature operation, and integrated timing control.
Supply support for LM3311SQX 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
Texas Instruments is a global semiconductor leader delivering analog and embedded processing solutions for industrial, automotive, and personal electronics markets.
The LM3311 product line targets integrated power management for TFT-LCD display systems, combining boost conversion, linear regulation, analog signal conditioning, and gate timing control in a single WQFN package to simplify display subsystem design.
FAQ
What is the function of the VFLK pin on the LM3311SQX?
The VFLK pin on the LM3311SQX is a timing input that determines when the TFT LCD panel is active (ON) or inactive (OFF). It accepts logic-level signals with 0.4V falling-edge and 1.4V rising-edge thresholds, and directly controls the gate pulse modulation (GPM) block to synchronize VGHM output with the display controller's frame timing. This ensures precise gate driver activation aligned to pixel data updates, minimizing display artifacts.
How do I set the output voltage of the boost converter in the LM3311SQX?
The boost output voltage of the LM3311SQX is set using the FB pin and an external resistor divider connected between VOUT and PGND. The FB pin is regulated to 1.263V, so the output voltage follows VOUT = 1.263V × (1 + RFB1/RFB2). For example, to achieve 8.5V output, use RFB1 = 576kΩ and RFB2 = 100kΩ. The LM3311SQX datasheet provides Equation (2) and design examples for accurate selection.
Can the LM3311SQX operate without using the GPM functionality?
Yes, the LM3311SQX can operate without GPM functionality. To disable it, tie VDPM low, connect VDD to VIN, and leave VFLK and VGHM unconnected or terminated appropriately. The boost converter, LDO, and op-amp remain fully functional. In this configuration, the LM3311SQX behaves as a standard step-up DC/DC converter with integrated LDO and op-amp - retaining all core power management capabilities while omitting gate timing control.
What thermal considerations apply to the LM3311SQX WQFN package?
The LM3311SQX uses a 24-lead WQFN package (RTW0024A) with an exposed die attach pad (DAP) internally connected to GND. For reliable thermal performance, AGND and PGND pins must be soldered directly to the DAP using multiple thermal vias to inner ground planes. The datasheet specifies θJA = 37°C/W under JEDEC JESD51-7 conditions; actual board-level θJA depends on copper area and via count. Thermal shutdown activates at 145°C with 20°C hysteresis, protecting against sustained overload.
How does the soft-start feature work on the LM3311SQX?
The LM3311SQX soft-start feature uses an internal 11µA current source to charge an external capacitor (CSS) connected to the SS pin. When CSS charges to the internal clamp voltage of 1.24V, the boost converter begins switching. Soft-start time is calculated as TSS = CSS × 1.24V / 11µA - for example, a 100nF capacitor yields ~11.3ms ramp time. This limits inrush current into output capacitors and prevents input voltage droop during startup, improving system reliability.
LM3311SQX Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 24-WFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Function:
- Step-Up
- Output Configuration:
- Positive
- Topology:
- Boost
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 2.5V
- Voltage - Input (Max):
- 7V
- Voltage - Output (Min/Fixed):
- 1.263V
- Voltage - Output (Max):
- 20V
- Current - Output:
- 2A (Switch)
- Frequency - Switching:
- 660kHz, 1.28MHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 24-WQFN (4x4)
LM3311SQX FAQ
1.How can I place an order for LM3311SQX through Aetrix?
Please submit a Request for Quotation (RFQ) for LM3311SQX 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 LM3311SQX reliable?
The price and inventory of LM3311SQX are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM3311SQX is usually 5 days.
3.What payment methods are accepted for LM3311SQX?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM3311SQX transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM3311SQX?
LM3311SQX orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM3311SQX 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 LM3311SQX?
For technical support, including LM3311SQX datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM3311SQX requirements.
6.How does Aetrix verify that LM3311SQX is sourced from the original manufacturer or authorized distributors?
All LM3311SQX 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 LM3311SQX meets industry standards.
7.What is the process for return or replacement of LM3311SQX?
All LM3311SQX units undergo pre-shipment inspection (PSI). If there is an issue with LM3311SQX, 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 LM3311SQX part is unused and in its original packaging.
Return procedure for LM3311SQX:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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