LM27961

Features:

* Drives 4 Individual Common-Anode LEDs with up to 20mA each for a Main Display Backlight
* Drives 3 Individual Common-Cathode LEDs with up to 20mA each for a Sub-Display Backlight
* Independent Resistor-Programmable Current Setting
* Excellent Current and Brightness Matching
* High-Efficiency 3/2x Charge Pump
* Extended Li-Ion Input: 2.7V to 5.5V
* PWM Brightness Control: 100Hz - 1kHz
*18-bump Thin Micro SMD Package: (2.1mm x 2.4mm x 0.6mm) 


Application


1 Mobile Phone Display Lighting
2 Mobile Phone Keypad Lighting
3 PDAs
4 General LED Lighting


Specifications

If Military/Aerospace specified devices are required,please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
V_IN pin voltage                                                                    -0.3V to 7.1V
E_NA, E_NB pin voltages                                                 -0.3V to (VIN+0.3V)
                                                                                              w/ 6.0V max
I_Dxx Pin Voltages                                                                          -0.3V to
                                                                                           (VPOUT+0.3V)
                                                                                              w/ 6.0V max
Continuous Power Dissipation       Internally Limited
(Note 3)

Junction Temperature (T_J-MAX)                                                      150^oC
Storage Temperature Range                                       -65oC to +150^o C
Maximum Lead Temperature                                                         265^oC
(Soldering, 10 sec.)

E_SD Rating (Note 4)
Human Body Model - I_Dxx Pins:                                                     1.0kV
Human Body Model - All other Pins:                                               2.0kV
Machine Model - I_Dxx Pins:                                                             100V
Machine Model - All Other Pins:                                                      200V

 

Input Voltage Range                                                            2.7V to 5.5V
Junction Temperature (T_J) Range                               -30°C to +125°C
Ambient Temperature (T_A) Range                                -30°C to +85°C
(Note 5)

Description

The LM27961 is a charge-pump-based white-LED driver that is ideal for mobile phone display backlighting. It is intended to drive 4 LEDs for a main phone display backlight and 3 LEDs for a sub-display backlight. Regulated internal current sources deliver excellent current and brightness matching in all LEDs.

The LED driver current sources are split into two independently controlled groups. The primary group (Group A) can be used to backlight a main phone display with up to 4 LEDs. The low-side current drivers of Group A accommodate common-anode-type LEDs. The second group (Group B) can backlight a secondary display with up to 3 LEDs. The high-side current drivers of Group B accommodate commoncathode- type LEDs. Both Group A and Group B can also drive standard two-terminal LEDs, and provide other general lighting functions (keypad lighting, fun lighting, etc). The brightness of the two LED groups can be adjusted independentlywith external resistors.

The LM27961 works off an extended Li-Ion input voltage range (2.7V to 5.5V). Voltage boost is achieved with a highefficiency 3/2x-gain charge pump.
The LM27961 is available in National's chip-scale 18-bump micro SMD package.