MCP45HVX1 Datasheet, PDF (47/100 Pages) Microchip Technology – Single-Resistor Network

5.7 Shutdown Control
Shutdown is used to minimize the device’s current
consumption. The MCP45HVX1 has two methods to
achieve this:
• Hardware Shutdown Pin (SHDN)
• Terminal Control Register (TCON)
The Hardware Shutdown pin is backwards compatible
with the MCP42X1 devices.
5.7.1
HARDWARE SHUTDOWN PIN
(SHDN)
The SHDN pin is available on the potentiometer
devices. When the SHDN pin is forced active (V_IL):
• The P0A terminal is disconnected
• The P0W terminal is connected to the P0B termi-
nal (see Figure 4-5)
• The Serial Interface is NOT disabled, and all
Serial Interface activity is executed
The Hardware Shutdown Pin mode does NOT corrupt
the values in the volatile wiper registers nor the TCON
register. When the Shutdown mode is exited (SHDN
pin is inactive (V_IH)):
• The device returns to the wiper setting specified
by the volatile wiper value
• The TCON register bits return to controlling the
terminal connection state
A
W
B
FIGURE 5-10:
Hardware Shutdown
Resistor Network Configuration.
5.7.2
TERMINAL CONTROL REGISTER
(TCON)
The Terminal Control (TCON) register is a volatile
register used to configure the connection of each
resistor network terminal pin (A, B and W) to the
Resistor Network. This register is shown in Register 4-1.
The R0HW bit forces the selected resistor network into
the same state as the SHDN pin. Alternate low-power
configurations may be achieved with the R0A, R0W
and R0B bits.
When the R0HW bit is “0”:
• The P0A terminal is disconnected
• The P0W terminal is simultaneously connected to
the P0B terminal (see Figure 5-11)
MCP45HVX1
Note:
When the R0HW bit forces the resistor
network into the hardware SHDN state,
the state of the TCON0 register’s R0A,
R0W and R0B bits is overridden (ignored).
When the state of the R0HW bit no longer
forces the resistor network into the
hardware SHDN state, the TCON0
register’s R0A, R0W and R0B bits return
to controlling the terminal connection
state. In other words, the R0HW bit does
not corrupt the state of the R0A, R0W and
R0B bits.
The R0HW bit does NOT corrupt the values in the
volatile wiper registers nor the TCON register. When
the Shutdown mode is exited (R0HW bit = 1):
• The device returns to the wiper setting specified
by the volatile wiper value
• The TCON register bits return to controlling the
terminal connection state
A
W
B
FIGURE 5-11:
Resistor Network Shutdown
State (R0HW = 0).
5.7.3
INTERACTION OF SHDN PIN AND
TCON REGISTER
Figure 5-12 shows how the SHDN pin signal and the
R0HW bit signal interact to control the hardware
shutdown of the resistor network.
SHDN (from pin)
R0HW
(from TCON register)
To Pot 0 Hardware
Shutdown Control
FIGURE 5-12:
Interaction.
R0HW bit and SHDN pin
 2014 Microchip Technology Inc.
DS20005304A-page 47