PIC24FJ128GC010 Datasheet, PDF (268/472 Pages) Microchip Technology – 16-Bit Flash Microcontrollers with 12-Bit Pipeline A/D, Sigma-Delta A/D, USB On-The-Go and XLP Technology

PIC24FJ128GC010 FAMILY
19.1.2 HOST AND OTG MODES
19.1.2.1 D+ and D- Pull-Down Resistors
PIC24FJ128GC010 family devices have a built-in
15 k pull-down resistor on the D+ and D- lines. These
are used in tandem to signal to the bus that the micro-
controller is operating in Host mode. They are engaged
by setting the HOSTEN bit (U1CON<3>). If the OTGEN
bit (U1OTGCON<2>) is set, then these pull-downs are
enabled by setting the DPPULDWN and DMPULDWN
bits (U1OTGCON<5:4>).
19.1.2.2 Power Configurations
In Host mode, as well as Host mode in On-The-Go
operation, the “USB 2.0 OTG Specification” requires
that the host application should supply power on VBUS.
Since the microcontroller is running below VBUS, and is
not able to source sufficient current, a separate power
supply must be provided.
When the application is always operating in Host mode,
a simple circuit can be used to supply VBUS and
regulate current on the bus (Figure 19-5). For OTG
operation, it is necessary to be able to turn VBUS on or
off as needed, as the microcontroller switches between
Device and Host modes. A typical example using an
external charge pump is shown in Figure 19-6.
FIGURE 19-5:
HOST INTERFACE EXAMPLE
150 µF
Micro A/B
Connector
VBUS
D+
D-
ID
GND
Thermal Fuse
Polymer PTC
+5V +3.3V +3.3V
PIC^® MCU
VDD
VUSB3V3
2 k
0.1 µF
3.3V
2 k
A/D Pin
VBUS
D+
D-
ID
VSS
FIGURE 19-6:
OTG INTERFACE EXAMPLE
Micro A/B
Connector
VBUS
D+
D-
ID
GND
4.7 µF
MCP1253
GND
C+
VIN
SELECT
1 µF
40 k
C-
VOUT
SHND
PGOOD
VDD
10 µF
+3.3V _+3.3V
0.1 µF
3.3V
PIC^® MCU
VDD
VUSB3V3
I/O
I/O
VBUS
D+
D-
ID
VSS
DS30009312B-page 268
 2012-2013 Microchip Technology Inc.