WM8959
Pre-Production
TEMPERATURE SENSOR OUTPUT
The WM8959 output drivers can generate a large amount of heat. To protect the device from
overheating a thermal shutdown function is provided (see "Thermal Shutdown" section for more
information).
The polarity of the Thermal Shutdown sensor may be controlled by register bit TEMPOK_POL. Note
that this polarity inversion bit applies to the Interrupt register behaviour only; it does not affect the
direct GPIO output of the Temperature Sensor function. The associated interrupt event may be
masked or enabled by register bit TEMPOK_IRQ_ENA. The Temperature status bit contained in the
IRQ Register (R18) may be read at any time or else in response to an Interrupt event. See Table 47
for more details of the Interrupt function.
If direct output of the Temperature status bit is required to the external pins of the WM8959, the
following register settings are required:
•
•
•
•
•
•
GPIO1_ENA = 1 (only required if using GPIO1)
AIF_SEL = 0 (only required if using GPIO3, GPIO4 or GPIO5)
AIF_TRIS = 0
GPIOn_SEL = 0101 for the selected GPIO Temperature status output pin
GPIOn_PU = 0 for the selected GPIO Temperature status output pin
GPIOn_PD = 0 for the selected GPIO Temperature status output pin
The register fields used to configure the Temperature Sensor GPIO function are described in Table
43.
REGISTER BIT
ADDRESS
LABEL
DEFAULT
DESCRIPTION
R23 (17h)
11
TEMPOK_POL
(rw)
1b
Temperature Sensor polarity
0 = Non-inverted
1 = Inverted
R22 (16h)
11
TEMPOK_IRQ_
ENA
0b
Temperature Sensor IRQ Enable
0 = disabled
1 = enabled
Table 43 Temperature Sensor GPIO Control
The temperature sensor function operates according to the following truth table:
LABEL
VALUE
DESCRIPTION
Overheat temperature exceeded
Overheat temperature not exceeded
Temperature Sensor output
Temperature Sensor output
0
1
Table 44 Truth Table for GPIO Output of Temperature Sensor Function
PP, May 2008, Rev 3.1
80
w
WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
