16-Port Constant-Current Led Drivers Are Rated at 36V for Lighting and Signage; Extra Fail-Safe Features Support Safety-Related Applications
SUNNYVALE, CA-October 26, 2005-Maxim Integrated Products (NASDAQ: MXIM) introduces the MAX6971/MAX6983 16-port and the MAX6970/MAX6980/MAX6981 8-port constant-current LED drivers. All these LED drivers feature a 25MHz, 4-wire, industry-standard SPI-compatible serial interface. The 16 or 8 open-drain, constant-current-sinking LED driver outputs are rated at 36V. Using a single external resistor with a 2% current matching between outputs and 6% matching between cascaded devices, each port can sink up to 55mA for all LEDs. They operate from a 3V to 5.5V supply and are specified for the -40°C to +125°C operating range. All the devices are designed to support standard lighting and signage applications.
The MAX6971/MAX6983 16-port drivers use the industry-standard, shift-register-plus-latch-type serial interface. The driver accepts data shifted into a 16-bit shift register using data input, DIN, and clock input, CLK. Input data appears at the DOUT output 16 clock cycles later to allow cascading of multiple devices. The latch-enable input, LE, loads the 16 bits of shift register data into a 16-bit output latch to determine which LEDs are on and which are off. The output enable, OE-bar, gates all 16 outputs on and off, and is fast enough to be used as a PWM input for LED intensity control.
Some lighting or signage applications require LED fault detection and fail-safe protection, which the 16-port MAX6983 and 8-port MAX6980 are unique to provide. A LED fault-detect feature reports open-circuit LED faults in the data stream. A watchdog timer clears the screen if the serial interface fails for more than 1s. The fault detection and watchdog alleviate the need for tedious, external protective circuitry, which saves design time and lowers the cost of traffic and marquee signs, gaming, and architectural lighting applications.
Among the 8-port LED drivers, the MAX6970 provides standard, register-latched LED driver functionality. MAX6981 adds LED open-circuit fault-detection.
The 16-port MAX6971/MAX6983 are available in 24-pin TSSOP and 24-pin narrow PDIP packages, while the 8-port MAX6970/MAX6980/MAX6981 are available in 16-pin TSSOP and PDIP packages. The price for the MAX6971 and MAX6983 16-port devices is $1.98 and $2.14, respectively. The MAX6970 is priced at $0.99, the MAX6981 at $1.03, and the MAX6980 at $1.11. All driver prices are 1000-up, FOB USA.
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