ADM00310 Microchip Technology, ADM00310 Datasheet - Page 6

• Manufacturer Part Number: ADM00310
• Description: BOARD EVAL FOR MCP3903 AFE
• Manufacturer: Microchip Technology
• Series: -r

Specifications of ADM00310

• Design Resources: MCP3903 Eval Brd BOM MCP3903 Eval Brd Schematic
• Main Purpose: Interface, Analog Front End (AFE)
• Embedded: Yes, MCU, 16-Bit
• Utilized Ic / Part: MCP3903, PIC24F, PIC24H, dsPIC33, MCP2200
• Primary Attributes: -
• Secondary Attributes: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

MCP2200
1.5.2.1
MCP2200 offers various options for power supply. To
meet the required USB signaling levels, MCP2200
device incorporates an internal LDO used solely by the
USB transceiver, in order to present the correct D+/D-
voltage levels.
Figure 1-2
transceiver LDO in relation with the V
rail. The output of the USB transceiver LDO is tied to
the V
required if the USB transceiver LDO provides the 3.3V
supply to the transceiver.
FIGURE 1-2:
The provided V
voltage levels present on the GPIO pins (Rx/Tx and
RTS/CTS). When V
a logical ‘1’ around 5V with the variations specified in
Section 3.1, DC
For applications that require a 3.3V logical ‘1’ level,
V
the 3.3V voltage. In this case, the internal USB trans-
ceiver LDO cannot provide the required 3.3V power. It
is necessary to also connect the V
MCP2200 to the 3.3V power supply rail. This way, the
USB transceiver is powered up directly from the 3.3V
power supply.
DS22228B-page 6
DD
USB
must be connected to a power supply providing
V
V
USB
D+
D-
DD
line. A capacitor connected to the V
shows the internal connections of the USB
Internal Power Supply Details
DD
Characteristics.
voltage has a direct influence on the
DD
MCP2200 INTERNAL
POWER SUPPLY DETAILS
is 5V, all of these pins will have
Transceiver
OUT
IN
LDO
3.3V
USB
DD
USB
power supply
pin of the
USB
pin is
1.5.2.2
In Bus Power Only mode, all power for the application
is drawn from the USB
the simplest power method for the device.
FIGURE 1-3:
In order to meet the inrush current requirements of the
USB 2.0 specifications, the total effective capacitance
appearing across V
than 10 µF. If it is not more than 10 µF, some kind of
inrush limiting is required. For more details on Inrush
Current Limiting, search for that subject in the current
Universal Serial Bus Specification.
According to the USB 2.0 specification, all USB devices
must also support a Low-Power Suspend mode. In the
USB Suspend mode, devices must consume no more
than 500 µA (or 2.5 mA for high powered devices that
are remote wake-up capable) from the 5V V
the USB cable.
The host signals the USB device to enter Suspend
mode by stopping all USB traffic to that device for more
than 3 ms.
The USB bus provides a 5V voltage. However, the USB
transceiver requires 3.3V for the signaling (on D+ and
D- lines).
During USB Suspend mode, the D+ or D- pull-up
resistor must remain active, which will consume some
of
(500 µA/2.5 mA). The V
external bypass capacitor. It is recommended that the
capacitor be a ceramic cap, between 0.22 and 0.47 µF.
Figure 1-4
LDO is used to provide 3.3V to the USB transceiver.
The voltage on the V
the GPIO pins (Rx/Tx and RTS/CTS). With V
these pins will have a logic ‘1’ of 5V with the variations
specified in
the
V
BUS
shows a circuit where MCP2200’s internal
Section 3.1, DC
allowed
USB Bus Powered (5V)
BUS
DD
BUS POWER ONLY
(Figure
 2011 Microchip Technology Inc.
USB
suspend
and ground must be no more
affects the voltage levels onto
pin is required to have an
Characteristics.
1-3). This is effectively
current
V
V
V
DD
SS
USB
BUS
DD
budget
line of
at 5V,