LP3944ISQEV National Semiconductor, LP3944ISQEV Datasheet
LP3944ISQEV
Specifications of LP3944ISQEV
Related parts for LP3944ISQEV
LP3944ISQEV Summary of contents
Page 1
... Maximum output sink current 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 © 2003 National Semiconductor Corporation Features n Internal power-on reset n Active low reset n Internal precision oscillator n Variable dim rates (from 6. 1.6s ...
Page 2
LP3944 Pin Out LP3944 Pin Description Pin # Name 1 LED0 2 LED1 3 LED2 4 LED3 5 LED4 6 LED5 7 LED6 8 LED7 9 GND ...
Page 3
Architectural Block Diagram For Explanation of LP3944 Operation, Please Refer to “Theory of Operation” in Application Notes. 3 20085303 www.national.com ...
Page 4
... Absolute Maximum Ratings 1) If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications A0, A1, A2, SCL, SDA, RST (Collectively called digital pins) Voltage on LED pins Junction Temperature Storage Temperature Power Dissipation (Note 3) ESD (Note 4) ...
Page 5
Electrical Characteristics Unless otherwise noted 5.5V. Typical values and limits appearing in normal type apply for boldface type apply over the entire junction temperature range for operation, T Symbol Parameter INTERFACE (SCL ...
Page 6
Application Notes THEORY OF OPERATION The LP3944 takes incoming data and feed them into several registers that control the frequency and the duty cycle of the LEDs. Two prescaler registers and two PWM registers pro- vide two individual rates to ...
Page 7
Application Notes (Continued write (SDA = “0” read (SDA = “1”) ack = acknowledge (SDA pulled down by either master or slave repeated start However READ function ...
Page 8
Application Notes (Continued) AUTO INCREMENT Auto increment is a special feature supported by the LP3944 to eliminate repeated chip and register addressing when data are to be written to or read from registers in sequential In the READ mode, when ...
Page 9
Application Notes (Continued) Address (Hex) Register Name 0x00 Input 1 0x01 Register 1 0x02 PSC0 0x03 PWM0 0x04 PSC1 0x05 PWM1 0x06 LS0 0x07 LS1 0x08 Register 8 0x09 Register 9 Note: Registers 1, 8 and 9 are empty and ...
Page 10
Application Notes (Continued) Bit # 7 Default value 1 PWM1 register determines the duty cycle of DIM1. The LED outputs are LOW (LED on) when the count is less than the value in PWM1 and HIGH (LED off) when it ...
Page 11
Application Notes (Continued) REDUCING I WHEN LEDS ARE OFF Q In many applications, the LEDs and the LP3944 share the same shown in Section Typical Application Circuit. DD When the LEDs are off, the LED pins are ...
Page 12
... BANNED SUBSTANCE COMPLIANCE National Semiconductor certifies that the products and packing materials meet the provisions of the Customer Products Stewardship Specification (CSP-9-111C2) and the Banned Substances and Materials of Interest Specification (CSP-9-111S2) and contain no ‘‘Banned Substances’’ as defined in CSP-9-111S2. ...