MCP9808
user-specified
temperature
boundary
(see
5.1.1
SENSOR CONFIGURATION
REGISTER (CONFIG)
Section 5.2.2 “Temperature Hysteresis (THYST)”.
The Continuous Conversion or Shutdown mode is
selected using bit 8. In Shutdown mode, the band gap
The MCP9808 has a 16-bit Configuration register
(CONFIG) that allows the user to set various functions for
a robust temperature monitoring system. Bits 10 through
0 are used to select the temperature alert output
hysteresis, device shutdown or Low-Power mode,
temperature boundary and critical temperature lock, and
temperature Alert output enable/disable. In addition, Alert
output condition (output set for TUPPER and TLOWER
temperature boundary or TCRIT only), Alert output status
and Alert output polarity and mode (Comparator Output
or Interrupt Output mode) are user-configurable.
temperature
sensor
circuit
stops
converting
temperature and the Ambient Temperature register
(TA) holds the previous temperature data (see
Section 5.2.1 “Shutdown Mode”). Bits 7 and 6 are
used to lock the user-specified boundaries TUPPER
,
TLOWER and TCRIT to prevent an accidental rewrite.
The Lock bits are cleared by resetting the power. Bits 5
through 0 are used to configure the temperature Alert
output pin. All functions are described in Register 5-2
(see Section 5.2.3 “Alert Output Configuration”).
The temperature hysteresis bits 10 and 9 can be used
to prevent output chatter when the ambient
temperature
gradually
changes
beyond
the
REGISTER 5-2:
CONFIG: CONFIGURATION REGISTER (→ ADDRESS ‘0000 0001’b)
U-0
—
U-0
—
U-0
—
U-0
—
U-0
—
R/W-0
R/W-0
R/W-0
R/W-0
SHDN
THYST
bit 15
bit 8
R/W-0
Crit. Lock
bit 7
R/W-0
R/W-0
R-0
R/W-0
R/W-0
R/W-0
Win. Lock
Int. Clear
Alert Stat.
Alert Cnt.
Alert Sel.
Alert Pol.
Alert Mod.
bit 0
Legend:
R = Readable bit
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
-n = Value at POR
bit 15-11
bit 10-9
Unimplemented: Read as ‘0’
THYST: TUPPER and TLOWER Limit Hysteresis bits
00= 0°C (power-up default)
01= +1.5°C
10= +3.0°C
11= +6.0°C
(Refer to Section 5.2.3 “Alert Output Configuration”.)
This bit can not be altered when either of the Lock bits are set (bit 6 and bit 7).
This bit can be programmed in Shutdown mode.
SHDN: Shutdown Mode bit
bit 8
0= Continuous conversion (power-up default)
1= Shutdown (Low-Power mode)
In shutdown, all power-consuming activities are disabled, though all registers can be written to or read.
This bit cannot be set to ‘1’ when either of the Lock bits is set (bit 6 and bit 7). However, it can be
cleared to ‘0’ for continuous conversion while locked (refer to Section 5.2.1 “Shutdown Mode”).
DS25095A-page 18
© 2011 Microchip Technology Inc.
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