WM8900LGEFK/RV Wolfson Microelectronics, WM8900LGEFK/RV Datasheet - Page 62

• Manufacturer Part Number: WM8900LGEFK/RV
• Description: Audio CODECs Ultra Low Power Hi-Fi CODEC
• Manufacturer: Wolfson Microelectronics

Specifications of WM8900LGEFK/RV

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

WM8900
THERMAL SHUTDOWN
w
Table 46 Jack Detect Control
DISABLED OUTPUTS
Whenever an analogue output is disabled, it remains connected to VREF through a resistor. This
helps to prevent pop noise when the output is re-enabled. The resistance between VREF and each
output can be controlled using register bit VROI. If a high impedance is desired for disabled
outputs, VROI can then be set to 1, increasing the resistance to about 20kΩ.
Table 47 Disabled Outputs to VREF Resistance
The headphone outputs can drive very large currents. To protect the WM8900 from overheating a
thermal shutdown circuit is included. If the device temperature reaches approximately 150
the thermal shutdown circuit is enabled (TEMP_SD = 1; TEMP_ENA = 1) the headphone amplifiers
(HP_L, HP_R) and the Line Outputs (LINEOUT_1L, LINEOUT_1R, LINEOUT_2L and
LINEOUT_2R) will be disabled.
TEMP_ENA must be set to 1 to enable the temperature sensor when using the TEMP_SD thermal
shutdown function. The output of the temperature sensor can also be output to the GPIO pin.
Table 48 Thermal Shutdown
R7 (07h)
Clocking 2
R30 (1Eh)
Additional
Control
R30 (1Eh)
Additional
Control
R18 (12h)
GPIO Control
REGISTER
REGISTER
REGISTER
ADDRESS
ADDRESS
ADDRESS
5:0
1
0
0
1
0
BIT
BIT
BIT
JD_EN0[5:0]
TOCLK_RATE
TOCLK_ENA
VROI
TEMP_SD
TEMP_ENA
LABEL
LABEL
LABEL
0
1
1
DEFAULT
DEFAULT
000000
0
0
DEFAULT
Output enables when selected jack
detection input is logic 0
JD_EN0[0] =1 enables LINEOUT_1L
JD_EN0[1] =1 enables LINEOUT_1R
JD_EN0[2] =1 enables LINEOUT_2R
JD_EN0[3] =1 enables LINEOUT_2R
JD_EN0[4] =1 enables Headphone
JD_EN0[5] =1 enables Charge Pump
Slow Clock Selection (Used for volume
update timeouts and for jack detect
debounce)
0 = SYSCLK / 2
1 = SYSCLK / 2
Slow Clock Enable (Must be enabled for
jack detect de-bounce)
0 = Slow Clock Disabled
1 = Slow Clock Enabled
VREF to Analogue Output Resistance
(Disabled Outputs)
0 = 500Ω from buffered VMID to output
1 = 20kΩ from buffered VMID to output
Thermal Shutdown Enable
0 = Thermal shutdown disabled
1 = Thermal shutdown enabled
(TEMP_ENA must be enabled for this
function to work)
Temperature Sensor Enable
0 = Temperature sensor disabled
1 = Temperature sensor enabled
PD, August 2008, Rev 4.0
DESCRIPTION
DESCRIPTION
DESCRIPTION
21
19
(Slower Response)
(Faster Response)
Production Data
0
C and
62