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MAX6955 Datasheet(Hoja de datos) 6 Page - Maxim Integrated Products |
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6 page ![]() Detailed Description The MAX6955 is a serially interfaced display driver that can drive up to 16 digits 7-segment, 8 digits 14-seg- ment, 8 digits 16-segment, 128 discrete LEDs, or a combination of these display types. Table 1 shows the drive capability of the MAX6955 for monocolor and bicolor displays. The MAX6955 includes 104-character ASCII font maps for 14-segment and 16-segment displays, as well as the hexadecimal font map for 7-segment displays. The characters follow the standard ASCII font, with the addi- tion of the following common symbols: £, , ¥, °, µ, ±, ↑, and ↓. Seven bits represent the 104-character font map; an 8th bit is used to select whether the decimal point (DP) is lit. Seven-segment LED digits can be con- trolled directly or use the hexadecimal font. Direct seg- ment control allows the MAX6955 to be used to drive bar graphs and discrete LED indicators. Tables 2, 3, and 4 list the connection schemes for 16-, 14-, and 7-segment digits, respectively. The letters in Tables 2, 3, and 4 correspond to the segment labels shown in Figure 1. (For applications that require mixed display types, see Tables 38–41.) Serial Interface Serial Addressing The MAX6955 operates as a slave that sends and receives data through an I2C-compatible 2-wire inter- face. The interface uses a serial data line (SDA) and a serial clock line (SCL) to achieve bidirectional commu- nication between master(s) and slave(s). A master (typ- ically a microcontroller) initiates all data transfers to and 2-Wire Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan 6 _______________________________________________________________________________________ Pin Description PIN SSOP PDIP NAME FUNCTION 1, 2, 34, 35, 36 1, 2, 38, 39, 40 P0–P4 General-Purpose I/O Ports (GPIOs). GPIO can be configured as logic inputs or open-drain outputs. Enabling key scanning configures some or all ports P0–P3 as key-switch matrix inputs with internal pullup and port P4 as IRQ output. 3 3 AD0 Address Input 0. Sets device slave address. Connect to GND, V+, SCL, or SDA to give four logic combinations. See Table 5. 4 4 SDA I 2C-Compatible Serial Data I/O 5 5 SCL I 2C-Compatible Serial Clock Input 6 6 AD1 Address Input 1. Sets device slave address. Connect to GND, V+, SCL, or SDA to give four logic combinations. See Table 5. 7–15, 22–31 7–15, 26–35 O0–O18 Digit/Segment Drivers. When acting as digit drivers, outputs O0 to O7 sink current from the display common cathodes. When acting as segment drivers, O0 to O18 source current to the display anodes. O0 to O18 are high impedance when not being used as digit or segment drivers. 16, 18 17, 18, 20 GND Ground 17 19 ISET Segment Current Setting. Connect ISET to GND through series resistor RSET to set the peak current. 19, 21 21, 23, 24 V+ Positive Supply Voltage. Bypass V+ to GND with a 47µF bulk capacitor and a 0.1µF ceramic capacitor. 20 22 OSC Multiplex Clock Input. To use internal oscillator, connect capacitor CSET from OSC to GND. To use external clock, drive OSC with a 1MHz to 8MHz CMOS clock. 32 36 BLINK Blink Clock Output. Output is open drain. 33 37 OSC_OUT Clock Output. OSC_OUT is a buffered clock output to allow easy blink synchronization of multiple MAX6955s. Output is push-pull. — 16, 25 N.C. Not Internally Connected |