MCP413X/415X/423X/425X
4.0
FUNCTIONAL OVERVIEW
4.1.2
BROWN-OUT RESET
This Data Sheet covers a family of thirty-two Digital
Potentiometer and Rheostat devices that will be
referred to as MCP4XXX. The MCP4XX1 devices are
the Potentiometer configuration, while the MCP4XX2
devices are the Rheostat configuration.
As the
shows, there are four
main functional blocks. These are:
•
•
•
•
When the device powers down, the device V
DD
will
cross the V
POR
/V
BOR
voltage.
Once the V
DD
voltage decreases below the V
POR
/V
BOR
voltage the following happens:
• Serial Interface is disabled
If the V
DD
voltage decreases below the V
RAM
voltage
the following happens:
• Volatile wiper registers may become corrupted
• TCON register may become corrupted
As the voltage recovers above the V
POR
/V
BOR
voltage
see
Serial commands not completed due to a brown-out
condition may cause the memory location to become
corrupted.
The POR/BOR operation and the Memory Map are
discussed in this section and the Resistor Network and
SPI operation are described in their own sections. The
commands are discussed in
4.2
Memory Map
4.1
POR/BOR Operation
The Power-on Reset is the case where the device is
having power applied to it from V
SS
. The Brown-out
Reset occurs when a device had power applied to it,
and that power (voltage) drops below the specified
range.
The devices RAM retention voltage (V
RAM
) is lower
than the POR/BOR voltage trip point (V
POR
/V
BOR
). The
maximum V
POR
/V
BOR
voltage is less then 1.8V.
When V
POR
/V
BOR
< V
DD
< 2.7V, the electrical
performance may not meet the data sheet
specifications. In this region, the device is capable of
incrementing, decrementing, reading and writing to its
volatile memory if the proper serial command is
executed.
The device memory is 16 locations that are 9-bits wide
(16x9 bits). This memory space contains four volatile
locations (see
TABLE 4-1:
Address
00h
01h
02h
03h
04h
05h
06h-0Fh
MEMORY MAP
Function
Memory Type
RAM
RAM
—
—
RAM
RAM
—
Volatile Wiper 0
Volatile Wiper 1
Reserved
Reserved
Volatile TCON Register
Status Register
Reserved
4.2.1
VOLATILE MEMORY (RAM)
4.1.1
POWER-ON RESET
There are four Volatile Memory locations. These are:
• Volatile Wiper 0
• Volatile Wiper 1
(Dual Resistor Network devices only)
• Status Register
• Terminal Control (TCON) Register
The volatile memory starts functioning at the RAM
retention voltage (V
RAM
).
When the device powers up, the device V
DD
will cross
the V
POR
/V
BOR
voltage. Once the V
DD
voltage crosses
the V
POR
/V
BOR
voltage the following happens:
• Volatile wiper register is loaded with the default
wiper value
• The TCON register is loaded it’s default value
• The device is capable of digital operation
©
2008 Microchip Technology Inc.
DS22060B-page 33
MICROCHIP [ MICROCHIP TECHNOLOGY ]
