SE97TL datasheet(25/54 Pages) NXP

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SE97_5

Product data sheet

Rev. 05 — 6 August 2009

25 of 54

NXP Semiconductors

SE97

DDR memory module temp sensor with integrated SPD, 3.3 V

SHMD

Shutdown Mode.

0 — enabled Temperature Sensor (default)

1 — disabled Temperature Sensor

When shut down, the thermal sensor diode and ADC are disabled to save

power, no events will be generated. When either of the Critical Trip or Alarm

Window lock bits is set, this bit cannot be set until unlocked. However, it can be

cleared at any time.

Remark: SMBus Time-out works over the entire supply range of 1.7 V to 3.6 V

unless the shutdown bit (SHMD) is set and turns off the oscillator.

• The EEPROM read works over the entire supply range of 1.7 V to 3.6 V

whether or not SHMD is set because it does not need oscillator to function.

There is no undervoltage lockout, the device no longer responds at some

voltage below 1.7 V.

• EEPROM write works over the supply range of 3.0 V to 3.6 V, but not if

SHMD is set since the oscillator is needed to write to EEPROM. There is an

undervoltage lockout around 2.7 V that disables the RRPROM write

operation.

• Thermal sensor is operational over the supply range of 3.0 V to 3.6 V, but

not if SHMD is set since the oscillator is needed. There is an undervoltage

lockout around 2.7 V that disables the temp sensor.

Thermal sensor auto turn-off feature:

It was determined during testing of the SE97TP on 5 May 2008 that the Thermal

Sensor auto turn-off feature was not compatible with the JEDEC power supply

maximum ramp rate of 70 ms to 100 ms (slowest ramp rate) and this feature was

disabled for all SE97 samples/production devices tested after 6 May (wk 0818

date code is when the devices were assembled).

If there is a slow ramp rate on the supply voltage to 3.3 V the SE97 would be EE

read only and not Thermal Sensor. This is due to a feature integrated into the

device to automatically turn off the oscillator and place the thermal sensor in

shutdown if the SE97 was being used in SO-DIMM in notebook applications at

1.8 V to reduce the power consumption on the battery. The feature counts for

30 ms (

± 5 ms) after the oscillator starts working (around 1.2 V to 1.7 V) and if at

30 ms the voltage is greater than 2.4 V, the oscillator is left on and the Thermal

Sensor functions as normal. But if the voltage is less than 2.4 V at 30 ms, the

oscillator is turned off and the SE97 will think the part is in SPD only mode

defaulting to the oscillator and Thermal Sensor disabled (SHMD Shutdown

Mode bit 8 = 1). The oscillator and Thermal Sensor can be re-enabled by writing

a logic 0 to SHMD. It is important in RDIMM/server applications that the Thermal

Sensor is working as the default condition since the Thermal Sensor needs to be

compatible with the JEDEC power supply ramp rate (maximum ramp rate is

70 ms to 100 ms) so the Thermal Sensor auto turn-off feature was disabled

starting on 6 May 2008 by changing a programmable bit on the device during

ﬁnal test. There is no change in performance of the SE97 with this feature turned

off and was veriﬁed during characterization. There is no way to read the SE97

registers via the I2C-bus to determine if the Thermal Sensor auto turn-off feature

is enabled or disabled. This is set in a factory only register. You need to check

the date code or do an operational test (e.g., run up to < 2.4 V, hold, then go to

3.3 V, then read SHMD bit 8 in the Conﬁguration register to see if it is set to

logic 0 (e.g., oscillator running = feature disabled) or logic 1 (e.g., oscillator

turned off = feature enabled)). The Thermal Sensor auto turn-off feature is active

in all package options prior to wk 0818. The SE97TP and SE97TL were not yet

released to production so there is a clear line at release/orderable devices

versus samples with this feature disabled in all production devices.

Table 12.

Conﬁguration register (address 01h) bit description …continued

Bit

Symbol

Description

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