MAX3387ECUG+ Maxim Integrated Products, MAX3387ECUG+ Datasheet - Page 13

• Manufacturer Part Number: MAX3387ECUG+
• Description: IC TXRX RS232 250KBPS 24-TSSOP
• Manufacturer: Maxim Integrated Products
• Type: Transceiverr

Specifications of MAX3387ECUG+

• Number Of Drivers/receivers: 3/3
• Protocol: RS232
• Voltage - Supply: 3 V ~ 5.5 V
• Mounting Type: Surface Mount
• Package / Case: 24-TSSOP
• Propagation Delay Time Ns: 0.15 us
• Operating Supply Voltage: 3.3 V to 5 V
• Supply Current: 0.3 mA
• Operating Temperature Range: 0 C to + 70 C
• Data Rate: 250 Kbps
• Mounting Style: SMD/SMT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

The MAX3387E is designed with PDA applications in
mind. Two transmitters and two receivers handle stan-
dard full-duplex communication protocol, while an extra
transmitter allows a ring indicator signal to alert the
UART on the PC. Without the ring indicator transmitter,
solutions for these applications would require software-
intensive polling of the cradle inputs.
The ring indicate (RI) signal is generated when a PDA,
phone, or other “cradled” device is plugged into its cradle.
This generates a logic-low signal to the RI transmitter
input, creating +6V at the ring indicate pin. The PC’s
UART RI input is the only pin that can generate an inter-
rupt from signals arriving through the RS-232 port. The
interrupt routine for this UART will then service the RS-
232 full-duplex communication between the PDA and
the PC.
Figure 10. Loopback Test Results at 250kbps
R1OUT
T1OUT
3V, ±15kV ESD-Protected, AutoShutdown Plus
T1IN
RS-232 Transceiver for PDAs and Cell Phones
Typical PDA/Cell-Phone Application
V
CC
= 3.3V
______________________________________________________________________________________
2μs/div
5V/div
5V/div
5V/div
As cell phone design becomes more like that of PDAs,
cell phones will require similar docking ability and com-
munication protocol. Cell phones operate on a single
lithium-ion (Li+) battery and work with a power-supply
voltage of +2.7V to +4V. The baseband logic coming
from the phone connector can be as low as 1.8V at the
transceivers. To prevent forward biasing of a device
internal to the cell phone, the MAX3387E comes with a
logic power-supply pin (V
presented to the phone. The receiver outputs will sink
to zero for low outputs, but will not exceed V
highs. The input logic levels for the transmitters are also
altered, scaled by the magnitude of the V
device will work with V
charge-pump noise will begin to cause the transmitter
outputs to oscillate. This is useful with cell phones and
other power-efficient devices with core logic voltage
levels that go as low as 1.8V.
PROCESS: BiCMOS
For the latest package outline information and land patterns,
go to www.maxim-ic.com/packages. Note that a “+”, “#”, or
“-” in the package code indicates RoHS status only. Package
drawings may show a different suffix character, but the drawing
pertains to the package regardless of RoHS status.
PACKAGE TYPE
24 TSSOP
PACKAGE CODE
Package Information
U24+1
L
L
as low as 1.8V before the
) that limits the logic levels
Chip Information
DOCUMENT NO.
21-0066
L
input. The
L
for logic
13