National Semiconductor LP3943 Technical data
LP3943
RGB/White/Blue 16-LED Fun Light Driver
LP3943 RGB/White/Blue 16-LED Fun Light Driver
November 2003
General Description
LP3943 is an integrated device capable of independently
driving 16 LEDs. This device also contains an internal precision oscillator that provides all the necessary timing required for driving each LED. Two prescaler registers along
with two PWM registers provide a versatile duty cycle control. The LP3943 contains the ability to dim LEDs in SMBUS/
2
C applications where it is required to cut down on bus
I
traffic.
Traditionally, to dim LEDs using a serial shift register such as
74LS594/5 would require a large amount of traffic to be on
the serial bus. LP3943 instead requires only the setup of the
frequency and duty cycle for each output pin. From then on,
only a single command from the host is required to turn each
individual open drain output ON, OFF, or to cycle a programmed frequency and duty cycle. Maximum output sink
current is 25 mA per pin and 200 mA per package. Any ports
not used for controlling the LEDs can be used for general
purpose input/output expansion.
Typical Application Circuit
Features
n Internal power-on reset
n Active low reset
n Internal precision oscillator
n Variable dim rates (from 6.25 ms to 1.6s;
160 Hz– 0.625 Hz)
Key Specifications
n 16 LED driver (multiple programmable states — on, off,
input, and dimming at a specified rate)
n 16 Open drain outputs capable of driving up to 25 mA
per LED
Applications
n Customized flashing LED lights for cellular phones
n Portable Applications
n Digital Cameras
n Indicator Lamps
n General purpose I/O expander
n Toys
20079601
© 2003 National Semiconductor Corporation DS200796 www.national.com
LP3943 Pin Out
LP3943
(Top View)
See NS Package Number SQA24C
LP3943 Pin Description
Pin # Name Description
1 LED0 Output of LED0 Driver
2 LED1 Output of LED1 Driver
3 LED2 Output of LED2 Driver
4 LED3 Output of LED3 Driver
5 LED4 Output of LED4 Driver
6 LED5 Output of LED5 Driver
7 LED6 Output of LED6 Driver
8 LED7 Output of LED7 Driver
9 GND Ground
10 LED8 Output of LED8 Driver
11 LED9 Output of LED9 Driver
12 LED10 Output of LED10 Driver
13 LED11 Output of LED11 Driver
14 LED12 Output of LED12 Driver
15 LED13 Output of LED13 Driver
16 LED14 Output of LED14 Driver
17 LED15 Output of LED15 Driver
18 RST
19 SCL Clock Line for I
20 SDA Serial Data Line for I
21 V
22 A0 Address Input 0
23 A1 Address Input 1
24 A2 Address Input 2
DD
Active Low Reset Input
Power Supply
2
C Interface
2
C Interface
20079602
Ordering Information
LP3943, Supplied as 1000 Units, Tape and
Reel
LP3943ISQ LP3943ISQX LP3943
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LP3943, Supplied as 4500 Units, Tape
and Reel
Package Marking
Architectural Block Diagram
LP3943
For Explanation of LP3943 Operation, Please Refer to “Theory of Operation” in Application Notes.
20079603
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Absolute Maximum Ratings (Notes 2,
1)
LP3943
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
ESD (Note 4)
Human Body Model 2 kV
Machine Model 200V
Charge Device Model 1 kV
Distributors for availability and specifications.
V
DD
A0, A1, A2, SCL, SDA, RST
(Collectively called digital pins)
Voltage on LED pins V
Junction Temperature 150˚C
Storage Temperature −65˚C to 150˚C
Power Dissipation (Note 3) 400 mW
−0.5V to 6V
−0.5V to 6V
SS
6V
Operating Ratings (Notes 1, 2)
V
DD
Junction Temperature −40˚C to +125˚C
Operating Ambient Temperature −40˚C to +85˚C
Thermal Resistance (θ
LLP24 (Note 3) 37˚C/W
)
JA
Electrical Characteristics
Unless otherwise noted, VDD= 5.5V. Typical values and limits appearing in normal type apply for TJ= 25˚C. Limits appearing
in boldface type apply over the entire junction temperature range for operation, T
Symbol Parameter Conditions Typical
POWER SUPPLY
V
DD
I
Q
Supply Voltage 5 2.3 5.5 V
Supply Current No Load 350 550
Standby 2.0 5
∆I
Q
Additional Standby Current VDD= 5.5V, every LED pin
at 4.3V
V
POR
t
w
Power-On Reset Voltage 1.8 1.96 V
Reset Pulse Width 10 ns
LED
V
IL
V
IH
I
OL
LOW Level Input Voltage −0.5 0.8 V
HIGH Level Input Voltage 2.0 5.5 V
Low Level Output Current
VOL= 0.4V, VDD= 2.3V
(Note 6)
VOL= 0.4V, VDD= 3.0V 12
V
= 0.4V, VDD= 5.0V 15
OL
V
= 0.7V, VDD= 2.3V 15
OL
V
= 0.7V, VDD= 3.0V 20
OL
V
= 0.7V, VDD= 5.0V 25
OL
I
LEAK
C
I/O
Input Leakage Current VDD= 3.6, VIN=0VorV
DD
Input/Output Capacitance (Note 7) 2.6 5 pF
ALL DIGITAL PINS (EXCEPT SCL AND SDA PINS)
V
IL
V
IH
I
LEAK
C
IN
2
I
C INTERFACE (SCL AND SDA PINS)
V
IL
V
IH
V
OL
I
OL
F
CLK
t
HOLD
LOW Level Input Voltage −0.5 0.8 V
HIGH Level Input Voltage 2.0 5.5 V
Input Leakage Current −1 1 µA
Input Capacitance VIN= 0V (Note 7) 2.3 5 pF
LOW Level Input Voltage -0.5 0.3V
HIGH Level Input Voltage 0.7V
LOW Level Output Voltage 0 0.2V
LOW Level Output Current VOL= 0.4V 6.5 3 mA
Clock Frequency (Note 7) 400 kHz
Hold Time Repeated START
(Note 7)
Condition
t
CLK-LP
CLK Low Period (Note 7) 1.3 µs
= −40˚C to +125˚C. (Note 5)
J
Limit
Min Max
9
−1 1 µA
DD
0.6 µs
2 mA
DD
5.5 V
DD
2.3V to 5.5V
Units
µA
mA
V
V
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