|
|
PDF LP3944ISQX Data sheet ( Hoja de datos )
| Número de pieza | LP3944ISQX | |
| Descripción | RGB/White/Blue 8-LED Fun Light Driver | |
| Fabricantes | National Semiconductor | |
| Logotipo |  |
|
Hay una vista previa y un enlace de descarga de LP3944ISQX (archivo pdf) en la parte inferior de esta página. Total 12 Páginas | ||
|
No Preview Available !
November 2003
LP3944
RGB/White/Blue 8-LED Fun Light Driver
General Description
LP3944 is an integrated device capable of independently
driving 8 LEDs. This device also contains an internal preci-
sion 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
LP3944 contains the ability to dim LEDs in SMBUS/I2C
applications where it is required to cut down on bus 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. LP3944 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 pro-
grammed 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.
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 8 LED driver (multiple programmable states — on, off,
input, and dimming at a specified rate)
n 8 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
Typical Application Circuit
© 2003 National Semiconductor Corporation DS200853
20085301
www.national.com
1 page  
Electrical Characteristics (Continued)
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, TJ = −40˚C to +125˚C. (Note 5)
Symbol
Parameter
Conditions
Typical
Limit
Min Max
Units
I2C INTERFACE (SCL AND SDA PINS)
tCLK-LP
tCLK-HP
tSU
CLK Low Period
CLK High Period
Set-Up Time Repeated
START Condition
(Note 7)
(Note 7)
(Note 7)
1.3 µs
0.6 µs
0.6 µs
tDATA-HOLD
tDATA-SU
tSU
Data Hold Time
Data Set-Up Time
Set-Up Time for STOP
Condition
(Note 7)
(Note 7)
(Note 7)
300 ns
100 ns
0.6 µs
tTRANS
Maximum Pulse Width of
Spikes that Must Be
(Note 7)
Suppressed by the Input
50 ns
Filter of Both DATA & CLK
Signals
Note 1: Absolute Maximum Ratings are limits beyond which damage to the device may occur. Operating Ratings are conditions under which operation of the device
is guaranteed. Operating Ratings do not imply guaranteed performance limits. For guaranteed performance limits and associated test conditions, see the Electrical
Characteristics tables.
Note 2: All voltages are with respect to the potential at the GND pin.
Note 3: The Absolute Maximum power dissipation depends on the ambient temperature and can be calculated using the formula
P = (TJ — TA)/θJA, (1)
where TJ is the junction temperature, TA is the ambient temperature, and θJA is the junction-to-ambient thermal resistance. The 1.76W rating appearing under
Absolute Maximum Ratings results from substituting the Absolute Maximum junction temperature, 150˚C, for TJ, 85˚C for TA, and 37˚C/W for θJA. More power can
be dissipated safely at ambient temperature below 85˚C. Less power can be dissipated safely at ambient temperatures above 85˚C. The Absolute Maximum power
dissipation can be increased by 27 mW for each degree below 85˚C, and it must be de-rated by 27 mW for each degree above 85˚C. For Operating Ratings
maximum power dissipation, TJ = 125˚C and TA = 85˚C
Note 4: The human-body model is 100 pF discharged through 1.5 kΩ. The machine model is 0Ω in series with 220 pF.
Note 5: Limits are guaranteed. All electrical characteristics having room-temperature limits are tested during production with TJ = 25˚C. All hot and cold limits are
guaranteed by correlating the electrical characteristics to process and temperature variations and applying statistical process control.
Note 6: Each LED pin should not exceed 25 mA and the package should not exceed a total of 200 mA.
Note 7: Guaranteed by design.
Typical Performance Characteristics
Frequency vs. Temp
(TA = −40˚C to +85˚C),
VDD = 2.3V to 3.0V
20085317
5
www.national.com
5 Page 
Application Notes (Continued)
REDUCING IQ WHEN LEDS ARE OFF
In many applications, the LEDs and the LP3944 share the
same VDD, as shown in Section Typical Application Circuit.
When the LEDs are off, the LED pins are at a lower potential
than VDD, causing extra supply current (∆IQ). To minimize
this current, consider keeping the LED pins at a voltage
equal to or greater than VDD.
FIGURE 9. Methods to Reduce IQ When LEDs Are Off
Application Circuit
20085314
20085315
11 www.national.com
11 Page | ||
| Páginas | Total 12 Páginas | |
| PDF Descargar | [ Datasheet LP3944ISQX.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| LP3944ISQ | RGB/White/Blue 8-LED Fun Light Driver | National Semiconductor |
| LP3944ISQ | RGB/White/Blue 8-LED Fun Light Driver | National Semiconductor |
| LP3944ISQX | RGB/White/Blue 8-LED Fun Light Driver | National Semiconductor |
| LP3944ISQX | RGB/White/Blue 8-LED Fun Light Driver | National Semiconductor |
| Número de pieza | Descripción | Fabricantes |
| SLA6805M | High Voltage 3 phase Motor Driver IC. |
 Sanken |
| SDC1742 | 12- and 14-Bit Hybrid Synchro / Resolver-to-Digital Converters. |
 Analog Devices |
|
DataSheet.es es una pagina web que funciona como un repositorio de manuales o hoja de datos de muchos de los productos más populares, |
| DataSheet.es | 2020 | Privacy Policy | Contacto | Buscar |