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Multiple-Display LED Driver with I2C-Compatible Brightness Control
Features
• Drives up to 8 LEDs with up to 30 mA of diode current each
• 32 exponential dimming steps with 800:1 dimming ratio for group A (up to 6 LEDs)
• 8 linear dimming states for groups B (up to 3 LEDs) and D1C
(1 LED)
• Programmable auto-dimming function
• 3 independently controlled LED groups via I2C-compatible interface
• Up to 90% efficiency
• Total solution size < 21 mm
• 0.4% accurate current matching
• Internal soft-start limits inrush current
• True shutdown isolation for LEDs
• Wide input voltage range (2.7V to 5.5V)
• Active high hardware enable
• Available in low-profile, micro SMD-20 packaging (1.615 x 2.015 x 0.6 mm)
LM2756 Typical Application Circuit
Group A ;
Group C
, Group B
t Y ft
i> t> t> t>
DIA D2A D3A D4A D53 D62 D1B
1 V|N
1+
15
1 HF
1 uF^ 1 uF^
LM2756
C1-C2+
C2-
HWFN SDIO SRL Isft
I2C Control Signals
Applications
Ideal for use in dual display LCD backlighting for portable applications, large format LCD backlighting, display backlighting with indicator light
LM2757 - Switched-Capacitor Boost Regulator with High Impedance Output in Shutdown
Features
• Dual gain converter (2x, 3/2x) with up to 93% efficiency
• Inductor-less solution uses only 4 small ceramic capacitors
• Total solution area < 12 mm
• True input-output and output-input disconnect
• Up to 180 mA output current capability (5V)
• Selectable 4.1V, 4.5V or 5.0V output
• Pre-regulation minimizes input current ripple
• 1.24 MHz switching frequency for a low-noise, low-ripple output voltage
• Integrated over current and thermal shutdown protection
• Available in tiny micro SMD-12 packaging (1.2 x 1.6 x 0.4 mm)
LM2757 Typical Application Circuit
VOUT = 4.1V (100mA), 4.5V (110mA) 5.0V (180mA)
VIN = 3.0V - 5.5V
B2,B3
A2
A3
;1uF ■ 0.47uF
1.0uF
> COUT
C1- LM2757
C2+
D3
0.47|lF
D2
C3
1
C1,C2
*Bump D1 is (NC) No Connect
Applications
USB/USB-OTG power, super capacitor charger, keypad LED driver, audio amplifier power supply
www.national.com/handheld
9

pageCatalog pdf di En 2012-05-22-31