DLP-USB245M-G DLP Design Inc, DLP-USB245M-G Datasheet - Page 9

• Manufacturer Part Number: DLP-USB245M-G
• Description: MODULE USB-TO-TTL PARL FIFO CONV
• Manufacturer: DLP Design Inc
• Series: DLP-USB245Mr

Specifications of DLP-USB245M-G

• Convert From (adapter End): USB
• Convert To (adapter End): DB9 Female
• Features: Integrated 6MHz-48MHz clock multiplier PLL
• Interface Type: USB
• Product: Interface Modules
• For Use With/related Products: Windows® 98 or higher, Mac OS 8.5 or higher
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant
• Other names: 813-1019

Figure 3 shows how to configure the DLP-USB245M to interface with a 3.3v logic device. In this example, the target
electronics provides the 3.3 volts via the VCCIO line (pin 10) which in turn will cause the FIFO interface IO pins to
drive out at 3.3v level.
Bus Powered Circuit with Power Control
USB Bus powered circuits need to be able to power down
in USB suspend mode in order to meet the <= 500uA total
suspend current requirement (including external logic).
Figure 4 shows how to use a discrete P-Channel Logic Level
MOSFET to control the power to external logic circuits. A
suitable device could be a Fairchild NDT456P or equivalent.
This configuration is suitable for powering external logic where
the normal supply current is <= 100mA and the logic to be
controlled does not generate an appreciable current surge
at power-up. For power switching external logic that takes
over 100mA or generates a current surge on powerup we
recommend that a dedicated power switch i.c with inbuilt “soft-start” is used instead of a MOSFET. A suitable power
switch i.c. for such an application would be a Micrel (www.micrel.com) MIC2025-2BM or equivalent.
Please note the following points in connection with power controlled designs –
a) The logic to be controlled must have it’s own reset circuitry so that it will automatically reset itself when power is re-
applied on coming out of suspend.
b) Set the soft pull-down option bit in the FT232BM EEPROM.
c) For 3.3v power controlled circuits VCCIO must not be powered down with the external circuitry (PWREN# gets it’s
VCC supply from VCCIO).
Figure 3
Copyright © DLP Design 2002
3.3V
10
11
12
3
System with 3.3 Volt
Bus-Powered 5V
Logic Interface
data
TXE#
RXF#
RD#
WR
8
Figure 4
3.3V
DLP-USB245M User Manual
10
11
12
3
Microcontroller
Power Controlled by
Power MOSFET
P-Channel
SLEEP#
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SLEEP#
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Microcontroller