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LM2711 Dataheets PDF



Part Number LM2711
Manufacturers National Semiconductor
Logo National Semiconductor
Description TFT Panel Module
Datasheet LM2711 DatasheetLM2711 Datasheet (PDF)

LM2711 TFT Panel Module July 2003 LM2711 TFT Panel Module General Description The LM2711 is a compact bias solution for TFT displays. It has a current mode PWM step-up DC/DC converter with a 1.4A, 0.17Ω internal switch. Capable of generating 8V at 300mA from a Lithium Ion battery, the LM2711 is ideal for generating bias voltages for large screen LCD panels. The LM2711 can be operated at switching frequencies of 600kHz or 1.25MHz, allowing for easy filtering and low noise. An external compensat.

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LM2711 TFT Panel Module July 2003 LM2711 TFT Panel Module General Description The LM2711 is a compact bias solution for TFT displays. It has a current mode PWM step-up DC/DC converter with a 1.4A, 0.17Ω internal switch. Capable of generating 8V at 300mA from a Lithium Ion battery, the LM2711 is ideal for generating bias voltages for large screen LCD panels. The LM2711 can be operated at switching frequencies of 600kHz or 1.25MHz, allowing for easy filtering and low noise. An external compensation pin gives the user flexibility in setting frequency compensation, which makes possible the use of small, low ESR ceramic capacitors at the output. The LM2711 uses a patented internal circuitry to limit startup inrush current of the boost switching regulator without the use of an external softstart capacitor. An external softstart pin enables the user to tailor the softstart to a specific application. The LM2711 contains 4 Gamma buffers capable of supplying 50mA source and sink. The TSSOP-20 package ensures a low profile overall solution. Features n 1.4A, 0.17Ω, internal power switch n VIN operating range: 2.2V to 7.5V n 600kHz/1.25MHz selectable frequency step-up DC/DC converter n 20 pin TSSOP package n Inrush current limiting circuitry n External softstart override n 4 Gamma buffers Applications n LCD Bias Supplies Typical Application Circuit 20046831 © 2003 National Semiconductor Corporation DS200468 www.national.com LM2711 Connection Diagram Top View 20046804 TJMAX TSSOP 20 package = 125˚C, θJA = 120˚C/W (Note 1) Pin Description Pin 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Name VSW VIN SHDN FSLCT Vs+ GMA1-in GMA2-in GMA3-in GMA4-in NC NC GMA4-out GMA3-out GMA2-out GMA1-out SS VC FB AGND GND Power switch input. Switching Regulator Power input. Shutdown pin, active low. Frequency Select pin. FSLCT = VIN for 1.25 MHz, FSLCT = AGND or floating for 600kHz. Gamma Buffer input supply. Gamma Buffer input. Gamma Buffer input. Gamma Buffer input. Gamma Buffer input. No Connection, leave open. No Connection, leave open. Gamma Buffer output. Gamma Buffer output. Gamma Buffer output. Gamma Buffer output. Soft start pin. Boost Compensation Network Connection. Output Voltage Feedback input. Gamma Buffer ground, Analog ground connection for Regulator. Switch Power Ground. Function www.national.com 2 LM2711 Pin Functions VSW(Pin 1): This is the drain of the internal NMOS power switch. Minimize the metal trace area connected to this pin to minimize EMI. VIN(Pin 2): Input Supply Pin. Bypass this pin with a capacitor as close to the device as possible. The capacitor should connect between VIN and GND. SHDN(Pin 3): Shutdown Pin. The shutdown pin signal is active low. A voltage of less than 0.3V disables the device. A voltage greater than 0.85V enables the device. FSLCT(Pin 4): Frequency Select Pin. Connecting FSLCT to AGND selects a 600 kHz operating frequency for the switching regulator. Connecting FSLCT to VIN selects a 1.25 MHz operating frequency. If FSLCT is left floating, the switching frequency defaults to 600 kHz. Vs+(Pin 5): Supply pin for the four Gamma buffers. Bypass this pin with a capacitor as close to the device as possible. The capacitor should connect between Vs+ and GND. GMA1-in(Pin 6):Gamma Buffer input pin. GMA2-in(Pin 7): Gamma Buffer input pin. GMA3-in(Pin 8): Gamma Buffer input pin. GMA4-in(Pin 9): Gamma Buffer input pin. NC(Pin 10):No Connection. NC(Pin 11): No Connection. GMA4-out(Pin 12): Gamma Buffer output pin. GMA3-out(Pin13): Gamma Buffer output pin. GMA2-out(Pin 14): Gamma Buffer output pin. GMA1-out(Pin 15): Gamma Buffer output pin. SS(Pin 16): Softstart pin. Connect capacitor to SS pin and AGND to slowly ramp inductor current on startup. VC(Pin 17): Compensation Network for Boost switching regulator. Connect resistor/capacitor network between VC pin and AGND for boost switching regulator AC compensation. FB(Pin 18): Feedback pin. Set the output voltage by selecting values of R1 and R2 using: Connect the ground of the feedback network to the AGND plane, which can be tied directly to the GND pin. AGND(Pin 19): Analog ground pin. Ground connection for the Gamma buffers and the boost switching regulator. AGND must be tied directly to GND at the pins. GND(Pin 20): Power ground pin. Ground connection for the NMOS power device of the boost switching regulator. GND must be tied directly to AGND at the pins. Ordering Information Order Number LM2711MT-ADJ LM2711MTX-ADJ Package Type TSSOP-20 TSSOP-20 NSC Package Drawing MTC20 MTC20 Supplied As 73 Units, Rail 2500 Units, Tape and Reel 3 www.national.com LM2711 Block Diagrams 20046803 20046851 www.national.com 4 LM2711 Absolute Maximum Ratings (Note 2) If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. VIN VSW Voltage FB Voltage VC Voltage SHDN Voltage FSLCT Voltage Supply Voltage, Vs+ Buffer Input Voltage Buffer.


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