CP2102N Datasheet, PDF (17/44 Pages) Silicon Laboratories – USBXpress Family

CP2102N Data Sheet
Functional Description
4.3.2 Dynamic Suspend
By default, the latch values for all pins remains static during USB Suspend.
Alternatively, the dynamic suspend feature sets the pin latch to a predefined state when the CP2102N device moves from the config-
ured USB state to the suspend USB state (see chapter nine of USB 2.0 specification for more information on USB device states). When
the device exits the suspend USB state, the pin latch is restored to the previous value before entering the suspend state. Dynamic
Suspend is configured separately for the GPIO pins and UART/Modem Control pins.
4.3.3 Output Mode
Each pin has two options for the output mode: push-pull and open-drain.
By configuring for push-pull operation, a pin operates as a push-pull output. The output voltage is determined by pin’s latch value. This
type of output is most often used to connect directly to another device or drive external circuitry like an LED.
By configuring for open-drain operation, a pin operates as an open-drain output or input. The output voltage is determined by the pin's
latch value. If the pin latch value is 1, the pin is pulled up to VIO (or VDD if the device does not have a VIO pin) through an on-chip pull-
up resistor. Open-drain outputs are typically used when interfacing to logic at a higher voltage than the VIO pin. These pins can be
safely pulled to the higher, external voltage through an external pull-up resistor if VDD meets the 3.3 Absolute Maximum Ratings re-
quirements.
4.3.4 Battery Charging (CHREN, CHR0, and CHR1)
When battery charging is enabled, the D+/D- signals will detect the type of current source attached and set the CHREN, CHR0, and
CHR1 pins appropriately. CHREN enables 100 mA source current, CHR0 enables 500 mA source current, and CHR1 enables 1.5 A
source current.
The charging system may draw up to the limit specified by CHREN, CHR0, and CHR1. If the system also is operational while charging,
the current set points for the ISET resistors should be decreased based on how much the system could be using during battery charge.
4.3.5 Remote Wakeup (WAKEUP)
The WAKEUP pin is an optional active low remote wakeup input. When the wakeup pin toggles from inactive to active (i.e. grounded)
and the CP2102N is in USB suspend, the CP2102N will begin the wakeup sequence.
Host software must enable USB remote wakeup for the device. In Windows, this is under Device Manager. To set this, right-click on the
device, select [Properties]>[Power Management] and enable the [Allow this device to wake the computer] feature.
4.3.6 Clock Output (CLK)
An optional clock output is available on CP2102N devices.
F_CLK
=
48 MHz
2×N
The valid values for N are 1 to 256.
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