LM2794 Datasheet, PDF (1/24 Pages) National Semiconductor (TI) – Current Regulated Switched Capacitor LED Supply with Analog and PWM Brightness Control

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
D1
C1-
D2
C2+
1PF
LM2794/95 ^D3
C2-
D4
SD
BRGT
ISET
GND
CHOLD
1PF
LED1
LED2
LED3
LED4
RSET
1
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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