MCP413X/415X/423X/425X
4.1.2
BROWN-OUT RESET
4.0
FUNCTIONAL OVERVIEW
When the device powers down, the device VDD will
cross the VPOR/VBOR voltage.
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.
Once the VDD voltage decreases below the VPOR/VBOR
voltage the following happens:
• Serial Interface is disabled
As the Device Block Diagram shows, there are four
main functional blocks. These are:
If the VDD voltage decreases below the VRAM voltage
the following happens:
• POR/BOR Operation
• Memory Map
• Volatile wiper registers may become corrupted
• TCON register may become corrupted
• Resistor Network
• Serial Interface (SPI)
As the voltage recovers above the VPOR/VBOR voltage
see Section 4.1.1 “Power-on Reset”.
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
Device Commands commands are discussed in
Section 7.0.
Serial commands not completed due to a brown-out
condition may cause the memory location to become
corrupted.
4.2
Memory Map
The device memory is 16 locations that are 9-bits wide
(16x9 bits). This memory space contains four volatile
locations (see Table 4-1).
4.1
POR/BOR Operation
The Power-on Reset is the case where the device is
having power applied to it from VSS. The Brown-out
Reset occurs when a device had power applied to it,
and that power (voltage) drops below the specified
range.
TABLE 4-1:
Address
MEMORY MAP
Function
Memory Type
00h
01h
02h
03h
04h
05h
Volatile Wiper 0
Volatile Wiper 1
RAM
RAM
—
The devices RAM retention voltage (VRAM) is lower
than the POR/BOR voltage trip point (VPOR/VBOR). The
maximum VPOR/VBOR voltage is less then 1.8V.
Reserved
Reserved
—
When VPOR/VBOR < VDD < 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.
Volatile TCON Register
Status Register
RAM
RAM
—
06h-0Fh Reserved
4.2.1 VOLATILE MEMORY (RAM)
4.1.1
POWER-ON RESET
There are four Volatile Memory locations. These are:
• Volatile Wiper 0
When the device powers up, the device VDD will cross
the VPOR/VBOR voltage. Once the VDD voltage crosses
the VPOR/VBOR voltage the following happens:
• Volatile Wiper 1
(Dual Resistor Network devices only)
• Volatile wiper register is loaded with the default
wiper value
• Status Register
• Terminal Control (TCON) Register
• The TCON register is loaded it’s default value
• The device is capable of digital operation
The volatile memory starts functioning at the RAM
retention voltage (VRAM).
© 2008 Microchip Technology Inc.
DS22060B-page 33
MICROCHIP [ MICROCHIP ]
