MAX3100EPD MAXIM [Maxim Integrated Products], MAX3100EPD Datasheet - Page 5

• Manufacturer Part Number: MAX3100EPD
• Description: SPI/Microwire-Compatible UART in QSOP-16
• Manufacturer: MAXIM [Maxim Integrated Products]

The MAX3100 universal asynchronous receiver trans-
mitter (UART) interfaces the SPI/Microwire-compatible,
synchronous serial data from a microprocessor (µP) to
asynchronous, serial-data communication ports (RS-
232, RS-485, IrDA). Figure 2 shows the MAX3100 func-
tional diagram.
The MAX3100 combines a simple UART and a baud-rate
generator with an SPI interface and an interrupt genera-
tor. Configure the UART by writing a 16-bit word to a
write-configuration register, which contains the baud rate,
data-word length, parity enable, and enable of the 8-word
receive first-in/first-out (FIFO). The write configuration
selects between normal UART timing and IrDA timing,
controls shutdown, and contains 4 interrupt mask bits.
Transmit data by writing a 16-bit word to a write-data
register, where the last 7 or 8 bits are actual data to be
transmitted. Also included is the state of the transmitted
parity bit (if enabled). This register controls the state of
_______________Detailed Description
______________________________________________________________Pin Description
QSOP
5, 12
10
11
13
14
15
16
1
2
3
4
6
7
8
9
PIN
DIP
10
11
12
13
14
—
1
2
3
4
5
6
7
8
9
_______________________________________________________________________________________
NAME
DOUT
SHDN
SCLK
GND
CTS
N.C.
RTS
V
DIN
IRQ
CS
RX
X2
X1
TX
CC
SPI/Microwire Serial-Data Input. Schmitt-trigger input.
SPI/Microwire Serial-Data Output. High impedance when CS is high.
SPI/Microwire Serial-Clock Input. Schmitt-trigger input.
Active-Low Chip-Select Input. DOUT goes high impedance when CS is high. IRQ, TX, and RTS
are always active. Schmitt-trigger input.
Active-Low Interrupt Output. Open-drain interrupt output to microprocessor.
Hardware-Shutdown Input. When shut down (SHDN = 0), the oscillator turns off immediately
without waiting for the current transmission to end, reducing supply current to just leakage
currents.
Ground
Crystal Connection. Leave X2 unconnected for external clock. See Crystal-Oscillator
Operation—X1, X2 Connection section.
Crystal Connection. X1 also serves as an external clock input. See Crystal-Oscillator
Operation—X1, X2 Connection section.
General-Purpose Active-Low Input. Read via the CTS register bit; often used for RS-232 clear-
to-send input (Table 1).
General-Purpose Active-Low Output. Controlled by the RTS register bit. Often used for
RS-232 request-to-send output or RS-485 driver enable.
Asynchronous Serial-Data (receiver) Input. The serial information received from the modem or
RS-232/RS-485 receiver. A transition on RX while in shutdown generates an interrupt (Table 5).
Asynchronous Serial-Data (transmitter) Output
Positive Supply Pin (2.7V to 5.5V)
No Connection. Not internally connected.
SPI/Microwire-Compatible
the RTS output pin. Received words generate an inter-
rupt if the receive-bit interrupt is enabled.
Read data from a 16-bit register that holds the oldest
data from the receive FIFO, the received parity data,
and the logic level at the CTS input pin. This register
also contains a bit that is the framing error in normal
operation and a receive-activity indicator in shutdown.
The baud-rate generator determines the rate at which the
transmitter and receiver operate. Bits B0 to B3 in the
write-configuration register determine the baud-rate divi-
sor (BRD), which divides down the X1 oscillator frequen-
cy. The baud clock is 16 times the data rate (baud rate).
The transmitter section accepts SPI/Microwire data, for-
mats it, and transmits it in asynchronous serial format
from the TX output. Data is loaded into the transmit-
buffer register from the SPI/Microwire interface. The
MAX3100 adds start and stop bits to the data and
clocks the data out at the selected baud rate (Table 7).
FUNCTION
UART in QSOP-16
5