The MAX17126 generates all the supply rails for thin-film transistor liquid-crystal display (TFT LCD) TV panels operating from a regulated 12V input. It includes a step-down and a step-up regulator, a positive and a negative charge pump, an operational amplifier, a high-accuracy high-voltage gamma reference, and a high-voltage switch control block. The MAX17126 can operate from input voltages from 8V to 16.5V and is optimized for an LCD TV panel running directly from 12V supplies.
The step-up and step-down switching regulators feature internal power MOSFETs and high-frequency operation allowing the use of small inductors and capacitors, resulting in a compact solution. The step-up regulator provides TFT source driver supply voltage, while the step-down regulator provides the system with logic supply voltage. Both regulators use fixed-frequency current-mode control architectures, providing fast load-transient response and easy compensation. A current-limit function for internal switches and output-fault shutdown protects the step-up and step-down power supplies against fault conditions. The MAX17126 provides soft-start functions to limit inrush current during startup. In addition, the MAX17126 integrates a control block that can drive an external p-channel MOSFET to sequence power to
source drivers.
The positive and negative charge-pump regulators provide TFT gate-driver supply voltages. Both output voltages can be adjusted with external resistive voltage-dividers. A logic-controlled, high-voltage switch block allows the manipulation of the positive gate-driver supply.
The MAX17126 includes one high-current operational amplifier designed to drive the LCD backplane (VCOM). The amplifier features high output current (±200mA), fast slew rate (45V/µs), wide bandwidth (20MHz), and rail-to-rail outputs.
Also featured in the MAX17126 is a high-accuracy, high-voltage adjustable reference for gamma correction.
The MAX17126 is available in a small (7mm x 7mm), ultra-thin (0.8mm), 48-pin Thin QFN package and operates over the -40°C to +85°C temperature range.
Key Features
Applications/Uses
8.0V to 16.5V IN Supply-Voltage Range
Selectable Frequency (500kHz/750kHz)
Current-Mode Step-Up Regulator
Fast Load-Transient Response
High-Accuracy Output Voltage (1.0%)
Built-In 20V, 4.2A, 100mΩ MOSFET
High Efficiency
Adjustable Soft-Start
Adjustable Current Limit
Low Duty-Cycle Operation (13.2VIN - 13.5V AVDD)
Current-Mode Step-Down Regulator
Fast Load-Transient Response
Built-In 20V, 3.2A, 100mΩ MOSFET
High Efficiency
3ms Internal Soft-Start
Adjustable Positive Charge-Pump Regulator
Adjustable Negative Charge-Pump Regulator
Integrated High-Voltage Switch with Adjustable Turn-On Delay
High-Speed Operational Amplifier
±200mA Short-Circuit Current
45V/µs Slew Rate
High-Accuracy Reference for Gamma Buffer
±1% Feedback Voltage
Up to 30mA Load Current
Low-Dropout Voltage 0.5V at 60mA
External p-Channel Gate Control for AVDD Sequencing
PGOOD Comparator
Input Undervoltage Lockout and Thermal-Overload Protection
