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Analog Devices Inc./Maxim Integrated MAX8790ETP+TG51
- Part No.:
- MAX8790ETP+TG51
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- LED Drivers
- Package:
- -
- Datasheet:
-
MAX8790ETP+TG51.pdf
- Description:
- INTEGRATED CIRCUIT
- Quantity:
- Payment:
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Inventory:2,206
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Product details
Overview
MAX8790ETP+TG51 from Maxim Integrated is a six-string white LED driver IC for LCD panel backlighting, featuring current-mode step-up control, ±1.5% inter-string current regulation accuracy, 4.5V–26V input range, 20mA fixed or 15–27mA adjustable full-scale LED current, and selectable 500kHz/750kHz/1MHz switching frequency. It drives up to six parallel LED strings with active current balancing in notebook, tablet, and handheld display systems.
For engineers reviewing the MAX8790ETP+TG51 datasheet, MAX8790ETP+TG51 pinout, MAX8790ETP+TG51 application, or MAX8790ETP+TG51 equivalent, this page delivers verified technical context, real-world dimming behavior (100:1 range via DPWM or analog PLL-based control), fault protection thresholds (OV = 1.23V, thermal shutdown at 170°C), package-validated thermal performance (20-pin 4mm × 4mm TQFN-EP), and confirmed alternative options for LCD backlight power management.
Technical Context
The MAX8790ETP+TG51 integrates a fixed-frequency current-mode step-up controller with six independent, matched current sinks (FB1–FB6), each capable of sinking up to 27mA with ≤450mV compliance voltage at 20mA. Its control architecture uses the lowest active FB_ voltage (LVC) to regulate output headroom and the highest (HVC) for open-string fault detection against VCC + 0.6V.
Dimming is implemented via dual-path logic: direct DPWM toggles the step-up switch and current sources synchronously, while analog mode employs an internal PLL (capture range 100–500Hz), digital comparator, and 8-bit DAC to linearly scale current down to 12.5%, augmented by digital dimming below that to achieve 1% average current. Fault response includes 65ms latched shutdown on sustained overvoltage or thermal events.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5V to 26V - supports wide-input industrial and portable LCD power rails without external pre-regulation. |
| LED Current Accuracy | ±1.5% between strings - ensures uniform brightness across all six LED strings under varying temperature and supply conditions. |
| Full-Scale LED Current | 20mA (default) or 15–27mA (adjustable via ISET resistor) - enables precise luminance tuning and thermal derating per display size. |
| Dimming Range | 100:1 (1% to 100%) - achieved via combined analog (down to 12.5%) and digital dimming, critical for high-contrast UI rendering. |
| Switching Frequency | 500kHz / 750kHz / 1MHz (selected via OSC pin) - allows trade-off between compact magnetics (1MHz) and peak efficiency (500kHz). |
| Feedback Voltage | 450mV at 20mA - minimizes power loss in current-sink stage and improves overall system efficiency. |
| Overvoltage Threshold | 1.23V on OV pin - sets precise output clamping level using external resistive divider, protecting LEDs during open-circuit faults. |
| Thermal Shutdown | 170°C junction temperature - provides robust protection during sustained overload or poor PCB thermal design. |
Pinout & Package
MAX8790ETP+TG51 is housed in a thermally enhanced, lead-free, 20-pin thin QFN package (4mm × 4mm, 0.5mm pitch) with exposed pad (EP) for low-thermal-resistance PCB mounting.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| FB1–FB6 | LED string cathode current-sink outputs | Each regulates one LED string with ±1.5% matching; grounded at startup disables corresponding string. |
| EXT | External N-channel MOSFET gate driver | Drives high-side switch with 2Ω typical on-resistance; supports scalable output power and voltage beyond integrated solutions. |
| OSC | Oscillator frequency selection | Tri-level input (GND/float/VCC) selects 500kHz/750kHz/1MHz - directly impacts inductor size and efficiency trade-offs. |
| ENA | Analog dimming enable control | High = PLL-based analog dimming; Low = direct DPWM - determines dimming linearity and minimum duty-cycle behavior. |
| BRT | Brightness PWM input | Accepts 100–500Hz signal in analog mode; >500Hz allowed in DPWM if pulse width ≥50µs - defines system-level brightness interface. |
| SHDN | Shutdown control | Logic-low (<0.8V) disables LDO, current sources, and controller; quiescent current drops to <10µA. |
| ISET | Full-scale LED current programming | Resistor-to-GND sets ILED = 20mA × (100kΩ/RISET); 74kΩ–133kΩ range yields 15–27mA. |
| FSET / CPLL | PLL frequency and loop compensation | FSET resistor sets PLL free-running frequency (166–500Hz); CPLL capacitor (0.1µF) stabilizes phase-lock response. |
| OV | Output overvoltage sense | Monitors VOUT divider center tap; trips at 1.23V to disable switch and clamp output during open-string faults. |
| VCC | Internal 5V LDO output | Supplies internal logic and EXT driver; bypassed with ≥1µF ceramic; disabled when SHDN = low. |
Key Features
| Feature | Design Value |
|---|---|
| Six independent current sinks with active balancing | Enables uniform backlighting across large LCD panels without external ballast resistors or discrete current mirrors. |
| Programmable 100:1 dimming with dual-mode control | Supports both high-fidelity analog dimming (linear down to 12.5%) and noise-immune DPWM for flexible system integration. |
| Integrated PLL for synchronized BRT-to-current translation | Eliminates external timing components and ensures jitter-free dimming even with variable-frequency host PWM sources. |
| Dual-loop fault protection (open/short LED, overvoltage, thermal) | Prevents catastrophic failure during field operation: HVC/LVC monitoring, 65ms fault timer, and latch-off shutdown. |
| Low 450mV FB regulation voltage at full current | Reduces power dissipation in current-source stage by >30% versus 1V-drop alternatives, improving thermal margin in thin displays. |
| External MOSFET drive with cycle-by-cycle current limit | Allows optimization of power stage for voltage/current requirements while maintaining consistent soft-start and overload behavior. |
Applications
| Notebook Display Backlight | Tablet Computer LCD |
|---|---|
Use Scenario: Driving 6 parallel strings of 8-series white LEDs in 13.3-inch IPS LCD panel with 400 nits brightness. IC Role / Device Role / Timing Role: Primary LED current regulator and boost controller; manages dynamic dimming via host-provided BRT PWM at 200Hz. Use Value: ±1.5% current matching eliminates visible banding; 450mV FB drop enables efficient operation from 12V rail with minimal thermal rise. |
Use Scenario: Backlight for 10.1-inch HD tablet display operating from single-cell Li-ion (3.0–4.2V) with external 5V supply. IC Role / Device Role / Timing Role: LED driver with VCC externally powered; uses low-frequency 500kHz switching to maximize battery runtime. Use Value: 100:1 dimming supports adaptive brightness control in ambient light; thermal shutdown protects against enclosure overheating during video playback. |
| Handheld Terminal Display | Subnotebook Embedded Display |
Use Scenario: Ruggedized industrial terminal with 7-inch WVGA LCD requiring reliable operation from 12–24V DC input. IC Role / Device Role / Timing Role: High-voltage LED driver with OV protection; configured for 1MHz switching to minimize inductor footprint. Use Value: Open/short LED fault detection prevents partial backlight failure; wide 4.5–26V input accommodates unregulated vehicle power. |
Use Scenario: Fanless subnotebook with ultra-thin chassis requiring minimal heat generation from display power circuitry. IC Role / Device Role / Timing Role: Six-string driver operating in analog dimming mode with PLL lock to host BRT signal. Use Value: Low 450mV compliance voltage reduces power loss by ~0.5W vs. higher-drop drivers; exposed pad ensures effective thermal conduction to PCB ground plane. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar six-string white LED driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM3409MH/NOPB | Single-string buck-boost LED driver; no integrated current balancing; requires external current mirrors for multi-string use. | Lacks native six-string support and active balancing - demands additional layout area and calibration for uniformity. | Select only if system uses discrete current-setting and requires automotive-grade AEC-Q100 qualification. |
| TPS68470RWER | Integrated six-string driver with I²C interface and programmable dimming curves; 3.3V-only input; no external MOSFET option. | Designed for ultra-thin mobile devices with PMIC-controlled power; lacks wide-input flexibility and thermal robustness of MAX8790ETP+TG51. | Prefer for space-constrained designs where I²C configurability outweighs input voltage range and thermal resilience needs. |
Compared with LM3409MH/NOPB and TPS68470RWER, MAX8790ETP+TG51 uniquely combines wide-input operation (4.5–26V), external MOSFET scalability, ±1.5% hardware-balanced current regulation, and dual-mode dimming - making it optimal for industrial and portable LCDs demanding reliability, uniformity, and design flexibility.
Availability
MAX8790ETP+TG51 is available at Aetrix Electronics and suitable for notebook display backlighting, tablet computer LCDs, and handheld terminal displays requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.
Supply support for MAX8790ETP+TG51 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
Maxim Integrated (now part of Analog Devices) is a semiconductor company specializing in high-performance analog, mixed-signal, and power management ICs for industrial, computing, and consumer applications.
The MAX8790 product line was designed specifically for high-efficiency, multi-string white LED backlighting in LCD panels - emphasizing precision current matching, robust fault protection, and flexible dimming for portable and embedded display systems.
FAQ
What is the function of the ENA pin on the MAX8790ETP+TG51?
The ENA pin on the MAX8790ETP+TG51 selects the dimming control mode: logic-high enables analog dimming (using the internal PLL and DAC to translate BRT PWM into linear current control), while logic-low enables direct DPWM mode (where the BRT signal directly gates the step-up switch and current sources). This choice affects dimming linearity, minimum achievable current (12.5% analog vs. 1% with added digital dimming), and EMI profile. The MAX8790ETP+TG51 must be enabled via SHDN before ENA state takes effect.
How does the MAX8790ETP+TG51 achieve ±1.5% current regulation between LED strings?
The MAX8790ETP+TG51 achieves ±1.5% inter-string current regulation through factory-matched, laser-trimmed current-sink transistors within its six FBx outputs, combined with active feedback using the lowest active FB_ voltage (LVC) to regulate boost output headroom. Each current sink operates with a low 450mV compliance voltage at 20mA, minimizing process- and temperature-induced mismatches. The MAX8790ETP+TG51 datasheet confirms this accuracy across -40°C to +85°C and full input voltage range (4.5V–26V), with no external calibration required.
Can the MAX8790ETP+TG51 operate from a 3.3V input supply?
No, the MAX8790ETP+TG51 cannot operate directly from a 3.3V input. Its absolute minimum input voltage is 4.5V, and the internal 5V LDO requires VIN > 5.5V for proper regulation. However, it supports low-input operation via external 5V bias: connect VCC to an external 5V supply and tie IN to that same rail (with internal diode protection), enabling use with 2.8V–5.5V input sources as shown in Figure 3 of the MAX8790ETP+TG51 datasheet. In this configuration, the MAX8790ETP+TG51 relies entirely on the external 5V supply for bias and gate drive.
What protection features are built into the MAX8790ETP+TG51?
The MAX8790ETP+TG51 includes open-LED and short-LED detection per string (via FBx overvoltage monitoring), output overvoltage protection (triggered at 1.23V on OV pin), cycle-by-cycle current limiting on the EXT-driven MOSFET, thermal shutdown at 170°C, and UVLO on VCC (4.25V threshold). Faults trigger a 65ms timer before latching shutdown; recovery requires cycling SHDN or power. These protections are hardware-implemented and do not rely on software or external supervision - ensuring fail-safe operation in unattended display systems.
How is the switching frequency selected on the MAX8790ETP+TG51?
The switching frequency of the MAX8790ETP+TG51 is selected via the tri-level OSC pin: connect OSC to GND for 500kHz, leave floating for 750kHz, or connect to VCC for 1MHz. This selection directly controls the step-up converter's oscillator and impacts external component sizing (smaller inductors/capacitors at 1MHz) and peak efficiency (highest at 500kHz due to reduced switching losses). The MAX8790ETP+TG51 datasheet specifies tolerance bands (e.g., 450–550kHz at GND) and confirms stable operation across temperature and load with any setting.
MAX8790ETP+TG51 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- -
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Type:
- -
- Topology:
- -
- Internal Switch(s):
- -
- Number of Outputs:
- -
- Voltage - Supply (Min):
- -
- Voltage - Supply (Max):
- -
- Voltage - Output:
- -
- Current - Output / Channel:
- -
- Frequency:
- -
- Dimming:
- -
- Applications:
- -
- Operating Temperature:
- -
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- -
- Supplier Device Package:
- -
MAX8790ETP+TG51 FAQ
1.How can I place an order for MAX8790ETP+TG51 through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX8790ETP+TG51 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 MAX8790ETP+TG51 reliable?
The price and inventory of MAX8790ETP+TG51 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX8790ETP+TG51 is usually 5 days.
3.What payment methods are accepted for MAX8790ETP+TG51?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX8790ETP+TG51 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX8790ETP+TG51?
MAX8790ETP+TG51 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX8790ETP+TG51 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 MAX8790ETP+TG51?
For technical support, including MAX8790ETP+TG51 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX8790ETP+TG51 requirements.
6.How does Aetrix verify that MAX8790ETP+TG51 is sourced from the original manufacturer or authorized distributors?
All MAX8790ETP+TG51 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 MAX8790ETP+TG51 meets industry standards.
7.What is the process for return or replacement of MAX8790ETP+TG51?
All MAX8790ETP+TG51 units undergo pre-shipment inspection (PSI). If there is an issue with MAX8790ETP+TG51, 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 MAX8790ETP+TG51 part is unused and in its original packaging.
Return procedure for MAX8790ETP+TG51:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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