CP2104 Errata

August 22, 2012
CP2104 Errata
Hardware Errata Status Summary
Errata #
Title
Impact
H1
USB D+/D- Driver Impedance
UART, GPIO, Suspend Signals
Driven Low After Power Cycling
Minor
H2
Major
Status
Affected Revisions
Fixed Revision
Revision E
Revision F
Revision A–E
Revision F
Impact Definition: Each erratum is marked with an impact, as defined below:
 Minor—Workaround exists.
 Major—Errata that do not conform to the data sheet or standard.
 Information—The device behavior is not ideal but acceptable. Typically, the data sheet will be
changed to match the device behavior.
Errata Details
H1. USB D+/D- Driver Impedance
Description: The output impedance of the drivers on the USB D+ and D- data lines is nominally 28 
but, in some cases, may be as low as 26 . The minimum USB specification for full-speed devices on
the D+ and D- data lines is 28 .
Impact: This may impact systems that need to be submitted for USB compliance testing. The
specification for USB compliance is a system-level parameter, not a chip-level parameter. In most
systems, the lower impedance of the device will not be a factor. A typical PCB will add 2-3  to the
effective driver impedance and bring the system level impedance within specifications.
Workaround: For systems that require USB certification, it is recommended to add some series
impedance (between 5 and 8 Ohms, ¼ watt or higher) to D+ and D- in the PCB design.
H2. UART, GPIO, Suspend Signals Driven Low after Power Cycling
Description: The UART, GPIO, and suspend signals will be driven low for approximately 40
microseconds after power cycling the device and then return to the configured reset state.
Impact: This may impact systems in which the CP2104 is connected to devices that are powered from a
separate supply and turned on before the CP2104 receives power through the 5 V regulator or through
VDD and VIO pins. The drop of the CP2104 signals may be seen as invalid data by the connected
devices.
400 West Cesar Chavez, Austin, TX 78701 (512) 416-8500 FAX (512) 416-9669 www.silabs.com
CP2104ER082212
Workaround: In systems that are affected by this drop, the CP2104 should be powered through the 5 V
regulator or through the VDD and VIO pins from the same supply used by devices that are connected to
the UART, GPIO, and suspend signals of the CP2104.
Data Sheet Errata Status Summary
The Documentation Errata is applicable to the following document:
 CP2104 Data Sheet Revision 1.0
Errata #
D1
Title
ROM Programming Voltage
Impact
Data Sheet
Minor
Issue Exists
Impact Definition: Each erratum is marked with an impact, as defined below:
 Minor—Workaround exists.
 Major—Errata that do not conform to the data sheet or standard.
 Information—The device behavior is not ideal but acceptable. Typically, the data sheet will be
changed to match the device behavior.
Errata Details
D1. ROM Programming Voltage
Description: The data sheet incorrectly indicates that VDD must remain at 3.3 V or higher to
successfully write to the configuration ROM. Instead, the voltage on the VIO pin must remain at 3.3 V or
higher when writing to the configuration ROM.
Impact: For systems that connect VDD and VIO together, there is no impact. For systems that have a
separate voltage source for VIO and are configuring the ROM in-system, VIO must remain at 3.3 V while
programming is in progress.
Resolution: This note will be fixed in the Revision 1.1 of the CP2104 Data Sheet.
400 West Cesar Chavez, Austin, TX 78701 (512) 416-8500 FAX (512) 416-9669 www.silabs.com
Similar pages