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When the thermal sensor is used in a noisy environment, a capacitor can be connected across DXP and DXN to provide
some noise filtering capabilities. However, large capacitances affect the accuracy of the temperature measurement. A
maximum capacitance of 300pF can be used to help mitigate the noise.
Thermal Diode Fault Conditions
9TCS1082 has the ability to detect an open or a short condition for each temperature sensor diode. An external diode fault
is defined as one of the following:
An open between DXP and DXN
A short from VDD to DXP
A short from VDD to DXN
The diode fault monitoring is enabled at the start of every temperature measurement. When an external diode fault is
detected, the ALERT# pin asserts and the temperature data reads 00h in the MSB and LSB of the corresponding
temperature registers:
DX1 MSB - byte[17], bit[2:0]
DX1 LSB - byte[16], bit[7:0]
During the fault condition, byte[13], bit[1] or bit[0], will be set depending on the channel that has the fault. Bit[1] corresponds
to DX1, and furthermore, an open/short fault flag will be set in register byte[14], bit[4].
DXP
DXN
PNP
transistor
i.e. to CPU
DXP
DXN
PNP
transistor
i.e. 2N3906
DXP
DXN
NPN
transister
i.e. 2N3904
9TCS1082
MOBILE ACCESS™—CLOCK SYNTHESIZER & TEMPERATURE SENSOR FOR PORTABLE DEVICES SYNTHESIZERS
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Temperature Threshold Alerts
Through register writes, the high and low temperature limits
can be set such that it will trigger an alert. This alert can be
monitored through the registers or can be sent to the
ALERT# pin. The programmable register to set the
thresholds is as follows:
(1) High Temperature Alert (default 127°C)
Where byte[0] is the high temperature alert for DX1.
(2) Low Temperature Alert (default 127°C)
Where byte[3] is the low alert for DX1.
Temperature Threshold Alert Status
When a temperature threshold alert is activated, a status
indicator bit is also set. Register byte[14], bit[6:5] will be set
depending on the high or low alert. Bit[6] is the high and
bit[5] is the low alert flag. To clear the alert, register byte[15],
bit[7] needs to be written with a "1". Writing this bit will also
clear the critical thermal warnings.
Temperature Threshold ALERT# Pin
The temperature threshold alerts are sent to the ALERT#
pin. To mask this alert being sent to the ALERT# pin, set
register byte[12], bit7 to logic 1. Bit7 corresponds to channel
1.
Consecutive Alerts
The number of temperature threshold alerts before the
assertion of the ALERT# pin can be set by the user through
register byte[6], bit[3:2] as follows:
Temperature Threshold Alert Alarm Register
The temperature channel has a readable register, byte[13],
bit[3:2] that is set when a temperature threshold alert has
occurred.
Critical Thermal Warnings
The 9TCS1082 will have register programmable critical
thermal threshold warnings for temperature sensor. Similar
to the temperature threshold alerts, the critical high
temperatures can be set such that a warning can be
dispatched to the THERM# pin and the readable registers.
The thermal warnings also have programmable hysteresis.
Each channel has its own programmable register to set the
thresholds as follows:
(1) Critical Thermal Warning (default 127°C)
Where byte[7] is the critical thermal warning for DX1.
Byte[2:0], Bit[7:0] Temperature
Bit[7] Sign Bit
Bit[6] 64°C
Bit[5] 32°C
Bit[4] 16°C
Bit[3] 8°C
Bit[2] 4°C
Bit[1] 2°C
Bit[0] 1°C
Byte[5:3], Bit[7:0] Temperature
Bit[7] Sign Bit
Bit[6] 64°C
Bit[5] 32°C
Bit[4] 16°C
Bit[3] 8°C
Bit[2] 4°C
Bit[1] 2°C
Bit[0] 1°C
Byte[6], Bit[3:2] Number of Alert Events
[00] (default) 1
[01] 2
[10] 3
[11] 4
Byte[9:7], Bit[6:0] Temperature
Bit[6] 64°C
Bit[5] 32°C
Bit[4] 16°C
Bit[3] 8°C
Bit[2] 4°C
Bit[1] 2°C
Bit[0] 1°C
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(2) Critical Thermal Warning Temperature Hysteresis
(default 4°C)
Critical Thermal Warning Status
When a critical warning is activated, a status indicator bit is
also set. Register byte[14], bit2 will be set depending on the
thermal sensor has detected the critical event.
Critical Thermal Warning THERM# Pin
The critical thermal warnings are sent to the THERM# pin
and requires a system register write to byte[15], bit[7] to
reset. This fault clear I2C write will also clear the
temperature threshold alerts
Active/Standby Mode
The thermal sensor has two modes in the temperature
conversion process:
(1) Active mode – In this mode the ADC will have a
selectable conversion rate for the temperature sensing.
(2) Standby mode – The system will command via I2C the
9TCS1082 to sample the temperature sensors. Once the
temperature reading from the ADC is updated, the
temperature sensor will be on stand-by awaiting the next
system request.
Register byte[15], bit[6] controls whether the thermal sensor
is in active or standby mode.
The conversion rate programmable register detail is as
follows:
The thermal sensor architecture has dynamic averaging to
smooth out the temperature conversion readings. To select
the number of temperature reading averages requires the
dynamic averaging function to be enabled, register byte[15],
bit[5]. The number of averages is then selected as follows:
Byte[12], Bit[4:0] Temperature
Bit[4] 16°C
Bit[3] 8°C
Bit[2] (default) 4°C
Bit[1] 2°C
Bit[0] 1°C
Byte[17], Bit[4:1] Conversion Rate
[0000] 16/sec
[0001] 8/sec
[0010] (default) 4/sec
[0011] 2/sec
[0100] 1/sec
[0101] 1/2 sec
[0110] 1/4 sec
[0111] 1/8 sec
[1000] 1/16 sec
[1001] 1/32 sec
[1010] 1/64 sec
Byte[6], Bit[1:0] Average the ADC Temperature
[00] 1
[01] 4
[10] 8
[11] 16

9TCS1082BNLG

Mfr. #:
Manufacturer:
IDT
Description:
Clock Synthesizer / Jitter Cleaner PLL THERMAL SENSOR AND FAN CONTROLLER
Lifecycle:
New from this manufacturer.
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