Information

Digital Block
Analog Block
Voltage Comparator
Control and
Feedback
clk
reset
bus
state of D–
state of D+
Analog Control Unit
Timer Unit
Bus interface &
registers
Current Source
Current Sink
D+
D
Voltage Source
D– pulldown
enable
D–
Figure 41-1. Block diagram
The USBDCD module consists of two main blocks:
• A digital block provides the programming interface (memory-mapped registers) and
includes the timer unit and the analog control unit.
• An analog block provides the circuitry for the physical detection of the charger,
including the voltage source, current source, current sink, and voltage comparator
circuitry.
41.2.2 Features
The USBDCD module offers the following features:
• Compliant with the latest industry standard specification: USB Battery Charging
Specification, Revision 1.1
• Programmable timing parameters default to values required by the industry
standards:
• Having standard default values allows for easy configuration- simply set the
clock frequency before enabling the module.
• Programmability allows the flexibility to meet future updates of the standards.
41.2.3 Modes of operation
The operating modes of the USBDCD module are shown in the following table.
Chapter 41 USB Device Charger Detection Module (USBDCD)
K20 Sub-Family Reference Manual, Rev. 2, Feb 2012
Freescale Semiconductor, Inc. 927