DM300023 Microchip Technology, DM300023 Datasheet - Page 8

• Manufacturer Part Number: DM300023
• Description: KIT DEMO DSPICDEM SMPS BUCK
• Manufacturer: Microchip Technology
• Series: dsPIC™r

Specifications of DM300023

• Main Purpose: DC/DC, Step Down
• Outputs And Type: 2, Non-Isolated
• Voltage - Input: 7 ~ 15V
• Regulator Topology: Buck
• Board Type: Fully Populated
• Utilized Ic / Part: dsPIC30F2020
• Processor To Be Evaluated: dsPIC30F202x/1010
• Interface Type: RS-232
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Output: -
• Voltage - Output: -
• Power - Output: -
• Frequency - Switching: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

dsPIC30F1010/202X
12. Module: EXTREF Pin
TABLE 2:
FIGURE 1:
DS80290J-page 8
Input Change Notification
Comparator Reference
The EXTREF pin is susceptible to voltage spikes
below V
into the pin. A voltage below V
outside the operating specification of the device;
however, the device is designed to tolerate small
voltage and current transients without experiencing
detrimental effects. The EXTREF pin is more
susceptible to negative current spikes than the
other pins on the dsPIC1010/202X Rev. A1
devices.
The addition of the 100 ohms resistor effectively
makes the EXTREF pin as robust as the other pins
on the device with respect to tolerating voltage and
current transients. In most of the configurations
shown in Table 2, the 100 ohms resistor will have
little effect on the operation of the pin. An
exception to this is when the pin is configured as
the comparator reference, EXTREF. Adding a
resistor in series with the reference voltage will
cause a slight offset in the gain of the comparator
DAC. This gain offset is related to the voltage drop
across the 100 ohms resistor.
The voltage seen at the EXTREF pin is given by
Equation 1.
External Timer Input
Pin Configuration
Comparator Input
Analog Input
Digital Input
SS
, which induces negative current flow
EXTREF PIN CONFIGURATIONS SUSCEPTIBLE TO NEGATIVE CURRENT
TRANSIENTS
dsPIC30F2020
ADDITION OF 100 OHMS RESISTOR ON EXTREF PIN
EXTREF
SS
dsPIC30F1010
on any I/O pin is
EXTREF
T1CK
RE6
CN0
N/A
N/A
100Ω
R1
EQUATION 1:
dsPIC30F2020
V
EXTREF
Work around
If the EXTREF pin is used in any of the
configurations
recommended that a 100 ohms 1/8W resistor be
added in series with the EXTREF pin (see
Figure 1).
Where:
• V
• V
• R is the resistor in series on the pin (100 ohms
EXTREF
voltage.
recommended).
T1CK
RE6
CN0
EXTREF
REF
N/A
N/A
= V
To Application Circuit
is the supplied comparator reference
REF
is the voltage seen at the EXTREF pin.
- R
EXTREF VOLTAGE
·
shown
(No of Comparators)
© 2008 Microchip Technology Inc.
40,000 ohm + R
in
dsPIC30F2023
EXTREF
CMP4D
Table 2,
RB9
AN9
N/A
N/A
·
V
REF
it
is