Rainbow Electronics AT76C551 - Manual (Page 10)

10
AT76C551
1612D–08/01
Signal Description – Pin Name Order
I = Input, O = Output, B = Bidirectional, Analog I = Analog Input, Analog O = Analog Output
Pin Name Type Description
Supply Pins
AGND Power Analog Ground
AVCC Power Analog Supply
GND Power Digital Ground
VCC Power Digital Supply
Global Pin
PC_RESET I Global Reset pin
Oscillator Pins
XTAL1 I Crystal oscillator input
XATL2 O Crystal oscillator output
EXT_13_MHZ I 13 MHz input clock
EXT_13_MHZ_OUT O 13 MHz output clock
EXT_OSC I External oscillator input
CLK_MODE1,
CLK_MODE0
I Clock Frequency Configuration
OSC_MODE I Internal/Extenal Clock Selector
LFT PLL Filter PLL loop filter pin
Memory Interface Pins
CSFL16 O Chip select when 16-bit Flash is used
CSSR O Chip select for low byte 8-bit SRAM
CSFL O Chip select for low byte Flash
CSSRH O Chip select for high byte SRAM
CSFLH O Chip select for high byte Flash
NWRITE O Memory write
NREAD O Memory read
NWORD I Selects between 8 and 16 memory access
MEM_ADDR [18:0] O Memory Address Bus – Signals MEM_ADDR [18:0] are address-bus output lines of Flash
and SRAM.
MEM_DATA [7:0] B Memory Data Bus – Signals MEM_DATA [7:0] are the bi-directional data bus lines for the
SRAM and Flash memory.
MEM_DATAH [7:0] B Memory Data Bus – Signals MEM_DATAH [7:0] are the bi-directional data bus lines for the
SRAM and Flash memory. These lines are used during 16-bit memory configuration.
P_OR_UN I Selects whether PCMCIA or USB will have direct access to the memories. When “1”
PCMCIA has direct access while when “0” USB has access