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LM2795 Dataheets PDF



Part Number LM2795
Manufacturers Texas Instruments
Logo Texas Instruments
Description Current Regulated Switched Capacitor LED Supply
Datasheet LM2795 DatasheetLM2795 Datasheet (PDF)

LM2794, LM2795 www.ti.com SNVS168L – JANUARY 2002 – REVISED MAY 2013 LM2794 /LM2795 Current Regulated Switched Capacitor LED Supply with Analog and PWM Brightness Control Check for Samples: LM2794, LM2795 FEATURES 1 •2 Regulated Current Sources with ±0.5% Matching between any Two Outputs • High Efficiency 3/2 Boost Function • Drives One, Two, Three or four White LEDs • 2.7V to 5.5V Input Voltage • Up to 80mA Output Current • Analog Brightness Control • Active-Low or High Shutdown Input ('94/.

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LM2794, LM2795 www.ti.com SNVS168L – JANUARY 2002 – REVISED MAY 2013 LM2794 /LM2795 Current Regulated Switched Capacitor LED Supply with Analog and PWM Brightness Control Check for Samples: LM2794, LM2795 FEATURES 1 •2 Regulated Current Sources with ±0.5% Matching between any Two Outputs • High Efficiency 3/2 Boost Function • Drives One, Two, Three or four White LEDs • 2.7V to 5.5V Input Voltage • Up to 80mA Output Current • Analog Brightness Control • Active-Low or High Shutdown Input ('94/95) • Very Small Solution Size and no Inductor • 2.3µA (typ.) Shutdown Current • 325kHz Switching Frequency (min.) • Constant Frequency Generates Predictable Noise Spectrum • Thin DSBGA Package: 2.08mm X 2.403mm X 0.600mm High APPLICATIONS • White LED Display Backlights • White LED Keypad Backlights • 1-Cell Li-Ion Battery-Operated Equipment Including PDAs, Hand-Held PCs, Cellular Phones DESCRIPTION The LM2794/95 is a fractional CMOS charge-pump that provides four regulated current sources. It accepts an input voltage range from 2.7V to 5.5V and maintains a constant current determined by an external sense resistor. The LM2794/5 delivers up to 80mA of load current to accommodate four White LEDs. The switching frequency is 325kHz. (min.) to keep the conducted noise spectrum away from sensitive frequencies within portable RF devices. Basic Application Circuit CIN 1PF C1 C2 VIN POUT C1+ 1PF C1C2+ 1PF LM2794/95 C2SD D1 D2 D3 D4 BRGT GND ISET CHOLD 1PF LED1 LED2 LED3 LED4 RSET 1 Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet. All trademarks are the property of their respective owners. 2 PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of the Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters. Copyright © 2002–2013, Texas Instruments Incorporated LM2794, LM2795 SNVS168L – JANUARY 2002 – REVISED MAY 2013 www.ti.com DESCRIPTION (CONTINUED) Brightness can be controlled by both linear and PWM techniques. A voltage between 0V and 3.0V may be applied to the BRGT pin to linearly vary the LED current. Alternatively, a PWM signal can be applied to the SD pin to vary the perceived brightness of the LED. The SD pin reduces the operating current to 2.3µA (typ.) The LM2794 is shut down when the SD pin is low, and the LM2795 is shut down when the SD pin is high. The LM2794/95 is available in a DSBGA CSP package. Connection Diagram E7 D6 E5 C7 A7 B6 A5 E3 A3 D2 B2 E1 C1 A1 Figure 1. DSBGA Package Bottom View Pin (1) A1 B2 C1 D2 E1 E3,E5,E7,D6 C7 B6 A7 A5 A3 Name C1+ C1− VIN GND C2− D1−4 ISET BRGT SD C2+ POUT PIN DESCRIPTION Function Positive terminal of C1 Negative terminal of C1 Power supply voltage input Power supply ground input Negative terminal of C2 Current source outputs. Connect directly to LED Current Sense Input. Connect 1% resistor to ground to set constant current through LED Variable voltage input controls output current The LM2794 has an active-low shutdown pin (LOW = shutdown, HIGH = operating). The LM2795 has an active-high shutdown pin (HIGH = shutdown, LOW = operating) that has a pull-up to VIN. Positive terminal of C2 Charge pump output (1) Note that the pin numbering scheme for the DSBGA package was revised in April, 2002 to conform to JEDEC standard. Only the pin numbers were revised. No changes to the physical location of the inputs/outputs were made. For reference purpose, the obsolete numbering had C1+ as pin 1, C1- as pin 2, VIN as pin 3, GND as pin 4, C2- as pin 5, D1-D4 as pin 6,7,8 & 9, Iset as pin 10, BRGT as pin 11, SD as pin 12, C2+ as pin 13, Pout as pin 14 These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam during storage or handling to prevent electrostatic damage to the MOS gates. 2 Submit Documentation Feedback Copyright © 2002–2013, Texas Instruments Incorporated Product Folder Links: LM2794 LM2795 LM2794, LM2795 www.ti.com SNVS168L – JANUARY 2002 – REVISED MAY 2013 Absolute Maximum Ratings (1)(2) VIN SD BRGT Continuous Power Dissipation (3) TJMAX (3) θJA (3) (4) Storge Temperature Lead Temp. (Soldering, 5 sec.) ESD Rating (5) Human Body Model Machine Model −0.5 to 6.2V max −0.5 to (VIN+0.3V) w/ 6.2V max −0.5 to (VIN+0.3V) w/ 6.2V max Internally Limited 135°C 125°C/W −65°C to +150°C 260°C 2kV 200V (1) Absolute maximum ratings indicate limits beyond which damage to the device may occur. Electrical specifications do not apply when operating the device beyond its rated operating conditions. (2) Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/ Distributors for availability and.


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