XR88C681J-F Exar Corporation, XR88C681J-F Datasheet - Page 52

• Manufacturer Part Number: XR88C681J-F
• Description: IC UART CMOS DUAL 44PLCC
• Manufacturer: Exar Corporation
• Type: CMOS Dual Channel UARTr

Specifications of XR88C681J-F

• Number Of Channels: 2, DUART
• Package / Case: 44-LCC (J-Lead)
• Features: *
• Fifo's: 1 Byte, 3 Byte
• Voltage - Supply: 5V
• With Parallel Port: Yes
• With Cmos: Yes
• Mounting Type: Surface Mount
• Data Rate: 1 Mbps
• Supply Voltage (max): 5.25 V
• Supply Voltage (min): 4.75 V
• Supply Current: 15 mA
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Mounting Style: SMD/SMT
• Operating Supply Voltage: 5 V
• Propagation Delay Time Ns: 400 ns
• No. Of Channels: 2
• Supply Voltage Range: 4.75V To 5.25V
• Operating Temperature Range: -40°C To +85°C
• Digital Ic Case Style: PLCC
• No. Of Pins: 44
• Filter Terminals: SMD
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant
• Other names: 1016-1329

Note: The user also has an option to drive the Oscillator Circuit with a TTL input signal, in lieu of using a crystal oscillator. If this
If the user desires to run numerous DUARTs from a single crystal oscillator, Figure 26 presents an approach and the
necessary circuitry to accomplish this objective.
Note: The user is urged not to use the 74LS14 Schmitt Trigger Inverter in lieu of the 74HC14 device. The input of the 74LS14 tends to
Figure 26. A Recommended Schematic to Drive Multiple DUARTs From the Same Crystal Oscillator.
Rev. 2.11
approach is used, the TTL must be driven into the X1/CLK pin, and the X2 pin must be left floating.
load down the oscillating signal from the DUART, to the point that the Schmitt Trigger inverter can no longer change state or
respond to the oscillator signal.
Figure 25. A Recommended Schematic for the XTAL Oscillator Circuitry
C1
C2
3.6864MHz
X1
Parallel Resonant Crystal
C1: 10pF + (Stray < 5pF)
C2: 10pF + (Stray < 5pF)
R1: 100ohm
R2: 100ohm
XR88C681
3.684MHz
Y1
52
X2
R1
R2
X1
X2
XR88C681
74HC14
To X1 inputs of
other DUARTs