CP2101
Rev. 1.6 14
9. Voltage Regulator
The CP2101 includes an on-chip 5-to-3 V voltage regulator. This allows the CP2101 to be configured as
either a USB bus-powered device or a USB self-powered device. These configurations are shown in
Figure 9.1 and Figure 9.2. When enabled, the 3 V voltage regulator output appears on the
V
DD
pin and can
be used to power external 3V devices. See Table 9.1 for the voltage regulator electrical characteristics.
Alternatively, if 3 V power is supplied to the
V
DD
pin, the CP2101 can function as a USB self-powered
device with the voltage regulator disabled. For this configuration, it is recommended that the REGIN input
be tied to the 3 V net to disable the voltage regulator. This configuration is shown in
Figure 9.3.
The USB max power and power attributes descriptor must match the device power usage and
configuration. See application note “AN144: CP2101 Customization Guide” for information on how to
customize USB descriptors for the CP2101.
Note:
It is recommended that additional decoupling capacitance (e.g., 0.1 µF in parallel with 1.0 µF) be provided
on the REGIN input.
Figure 9.1. Configuration 1: USB Bus-Powered
Table 9.1. Voltage Regulator Electrical Specifications
–40 to +85 °C unless otherwise specified
Parameter Conditions Min Typ Max Units
Input Voltage Range 4.0 — 5.25 V
Output Voltage Output Current = 1 to 100 mA* 3.0 3.3 3.6 V
VBUS Detection Input Threshold 1.0 1.8 4.0 V
Bias Current — 90 TBD µA
* The maximum regulator supply current is 100 mA.
Voltage Regulator (REG0)5 V In
3 V Out
VBUS Sense
REGIN
VBUS
From VBUS
To 3 V
Power Net
Device
Power Net
V
DD
CP2101
