Temperature-control system

The present invention relates to a temperature control system for a semiconductor integrated circuit having an on-chip temperature sensor (temperature sensor incorporated in the chip).

In high-performance semiconductor integrated circuits, parallelization of operations and speeding up of operation speeds are progressing, and the accompanying increase in chip temperature has become a problem.

When the chip temperature exceeds a certain limit, phenomena such as transistor destruction and ignition occur, so technology to prevent this is required.

One of the technologies is a management method in which a temperature sensor is incorporated in the chip, and when the chip temperature exceeds a predetermined value, a cooling fan is driven, the calculation speed is reduced, and the calculation is stopped. (See, for example, Patent Document 1).

In this method, before shipping, calibration is performed to adjust a predetermined temperature for starting the cooling fan. In calibration, the trimming value is determined so that an alert output is output at a predetermined temperature, and this value is stored in the fuse box.

Here, the chip environment of a predetermined temperature is created by, for example, a temperature-controlled plate, an oven, or a hot bath, but in order to obtain an accurate alert output at the predetermined temperature, self-heating due to a leak current in the chip is taken into consideration. Must be (see, for example, Patent Document 2).

However, even so, if the trimming values determined by pre-shipment calibration are used consistently, alert output will occur at temperatures other than the specified temperature due to changes in the characteristics of the temperature sensor, comparator, etc. after shipment over time. The problem arises.<patcit num="1"><text>Japanese Unexamined Patent Publication No. 10-41466</text></patcit><patcit num="2"><text>Japanese Unexamined Patent Publication No. 2003-149055</text></patcit>

<p> In the example of the present invention, we propose a management method that compensates for characteristic fluctuations due to changes over time by re-execution of calibration after shipment.</p>

<p> The temperature control system according to the example of the present invention includes the first and second temperature sensors formed in the chip, the trimming control circuit that determines the characteristics of the first temperature sensor based on the trimming value, and the first temperature. A non-volatile memory for storing trimming information regarding the characteristics of the initial state of the sensor and a system controller for giving temperature information regarding the chip temperature detected by the second temperature sensor at a predetermined time point to the trimming control circuit are provided. The trimming control circuit determines a new trimming value based on the temperature information and the trimming information, and updates the trimming value.</p><p> The temperature control system according to the example of the present invention includes first and second temperature sensors formed in the chip, a trimming control circuit that determines the characteristics of the first temperature sensor based on the trimming value, and the first temperature. A new trimming value is obtained based on a non-volatile memory that stores trimming information regarding the characteristics of the initial state of the sensor, temperature information regarding the chip temperature detected by the second temperature sensor at a predetermined time, and the trimming information. A system controller for determining the trimming is provided, and the trimming control circuit receives the new trimming value and updates the trimming value.</p><p> In the temperature control method according to the example of the present invention, regarding the trimming value that determines the characteristics of the first temperature sensor, the chip temperature is periodically detected by the second temperature sensor at a predetermined time point, and the temperature information regarding the chip temperature is obtained. And the trimming information regarding the characteristics of the first temperature sensor in the initial state, the characteristic fluctuation of the first temperature sensor is estimated, and the trimming value is updated.</p>

<p> According to the example of the present invention, the characteristic fluctuation due to the change with time can be compensated by the management method of re-executing the calibration after shipment.</p>

Hereinafter, the best mode for carrying out the example of the present invention will be described in detail with reference to the drawings.

1. Outline The temperature control system according to the example of the present invention is characterized in that calibration is performed not only before the chip is shipped but also after the chip is shipped.

However, for calibration after shipment, it is not possible to adopt a method of creating a predetermined temperature and adjusting the trimming value so that an alert output is output at the predetermined temperature as before shipment.

Therefore, in the example of the present invention, a relational expression for estimating a new trimming value in consideration of the characteristic change due to the change with time after shipment is created so that the alert output is always output at a predetermined temperature even after shipment.

The trimming value is updated periodically based on this relational expression.

Specifically, (1) Calibrate under two temperature conditions before shipping to obtain the relational expression. The relational expression for estimating the trimming value is (trimming value) = a × (chip temperature) + b equation (A), and the values before shipment a = a0, b = b0 are obtained, and this is calculated as For example, it is stored in advance in a non-volatile memory such as a fuse box.

At this stage, since the purpose is to obtain the relational expression, the trimming information does not need to be the coefficients a0 and b0 themselves. Information for obtaining the coefficients a0 and b0 may be stored, and the chip (or system) may be made to obtain the coefficients a0 and b0 based on this information.

(2) After shipment, calibrate and measure the temperature by OTD (on-chip thermal diode). Of the coefficients a and b of the relational expression in equation (A), the coefficient b changes with time.

Therefore, the value of the coefficient b1 at the current stage is calculated from the calibration result (trimming value) and the chip temperature (alert temperature) by OTD measurement. b1 = (Trimming value)-{a0 × (Chip temperature)} Equation (B) However, the chip temperature is the chip temperature at the time of calibration.

Then, when b1 is not equal to b0, the trimming value is updated based on (trimming value (updated value)) = a0 × (chip temperature) + b1 equation (C). However, the chip temperature here is a predetermined temperature at which an alert signal should be output.

When b1 is equal to b0, there is no need to update the trimming value. In this case, the update value is the same as the previous trimming value, and as a result, the calculation of equation (C) is unnecessary.

(3) After that, calibration and temperature measurement by OTD are performed in the same manner. The coefficient b2 at this stage is b2 = (trimming value)-{a0 × (chip temperature)} Equation (D) However, the chip temperature is the chip temperature at the time of calibration. Will be.

If b2 is not equal to b1, (trimming value (updated value)) = a0 × (chip temperature) + b2 Update the trimming value based on equation (E). However, the chip temperature here is a predetermined temperature at which an alert signal should be output.

When b2 is equal to b1, the trimming value does not need to be updated.

In such a method, the trimming value at the current stage may be obtained by calibration each time, or the trimming value obtained by the previous calibration may be stored in the non-volatile memory.

Regarding the value of the coefficient b (b = b0, b1, b2, ...), when comparing with each other as described above, it is necessary to store the previous value of the coefficient b in the non-volatile memory. For example, if instead of this, the calculation of the equation (C) or the equation (E) is performed every time without performing the comparison, it is not necessary to memorize the coefficient b.

Calibration after shipment should be performed at a time when the amount of heat generated in the chip becomes uniform, such as at power-on, clock stop, and reset.

According to such a configuration, even if the characteristics of the temperature sensor fluctuate after the chip is shipped, the accurate chip temperature can always be detected by updating the trimming value of the temperature sensor. Therefore, the margin in consideration of the temperature detection error can be reduced, and the cooling cost can be reduced.

2. Embodiments Next, some embodiments that seem to be the best will be described.

(1) First Embodiment Figure 1 shows the temperature control system related to the first embodiment. The chip (semiconductor integrated circuit) 11 is, for example, a microcomputer, a GPU (graphics processing unit), a processor including a CPU (central processing unit), a high-speed arithmetic unit having a plurality of independently operable arithmetic units, and the like. The type of chip 11 is not particularly limited.

A fuse box 12, a trimming control circuit 13, an alert circuit 14, and an OTD 15 are arranged in the chip 11.

The fuse box 12 stores trimming information (data required for calibration) of the alert circuit 14 before shipment.

The OTD15 detects the chip temperature at a time when the amount of heat generated in the chip becomes uniform, such as when the power is turned on, when the clock is stopped, and when the chip is reset. That is, the OTD 15 outputs a detection signal related to the chip temperature, and the temperature detection unit 16 obtains the chip temperature based on the detection signal from the OTD 15 and gives this to the system controller 17 as temperature information.

The system controller 17 gives the temperature information from the temperature detection unit 16 to the trimming control circuit 13 as a control signal.

The trimming control circuit 13 is based on the calibration result (trimming value) at the current temperature, the control signal (temperature information), and the trimming information of the alert circuit 14 before shipment from the fuse box 12, and the alert circuit 14 The new trimming value (updated value) of the alert circuit 14 is determined based on the characteristic fluctuation of the alert circuit 14, and the trimming value is updated.

The trimming value (update value) is input to the alert circuit 14 and also to the system controller 17.

Here, in this example, the temperature detection unit 16 is arranged outside the chip 11, but it may be arranged inside the chip 11. Further, the same function as the system controller 17 may be provided in the chip 11 and the system controller 17 may be omitted.

The number of OTD15 is not limited to one, and may be plural.

According to such a configuration, the alert circuit 14 can be calibrated periodically even after the chip is shipped. Therefore, even if the characteristics of the temperature sensor fluctuate after the shipment, the trimming value of the temperature sensor is updated. Accurate chip temperature can always be detected.

(2) Second Embodiment Figure 2 shows the temperature control system related to the second embodiment. The type of the chip (semiconductor integrated circuit) 11 is not particularly limited as in the first embodiment.

A fuse box 12, a trimming control circuit 13, an alert circuit 14, and an OTD 15 are arranged in the chip 11.

The fuse box 12 stores trimming information (data required for calibration) of the alert circuit 14 before shipment.

The OTD15 detects the chip temperature at a time when the amount of heat generated in the chip becomes uniform, such as when the power is turned on, when the clock is stopped, and when the chip is reset. That is, the OTD 15 outputs a detection signal related to the chip temperature, and the temperature detection unit 16 obtains the chip temperature based on the detection signal from the OTD 15 and gives this to the system controller 17 as temperature information.

The system controller 17 uses the alert circuit 14 based on the calibration result (trimming value) at the current temperature, the temperature information from the temperature detection unit 16, and the trimming information of the alert circuit 14 before shipment from the fuse box 12. The characteristic fluctuation of the alert circuit 14 is estimated, and a new trimming value (updated value) of the alert circuit 14 is determined based on this characteristic fluctuation.

The trimming control circuit 13 receives this new trimming value (updated value) from the system controller 17, and actually updates the trimming value for the alert circuit 14.

The trimming value (update value) is input to the alert circuit 14 and also to the system controller 17.

Here, the temperature detection unit 16 is arranged outside the chip 11 as in the first embodiment, but may be arranged inside the chip 11. Further, the same function as the system controller 17 may be provided in the chip 11 and the system controller 17 may be omitted.

The number of OTD15 is not limited to one, and may be plural.

Even in such a configuration, since the alert circuit 14 can be calibrated periodically after the chip is shipped, even if the characteristics of the temperature sensor fluctuate after the chip is shipped, the trimming value of the temperature sensor is updated so that the chip is always accurate. The temperature can be detected.

(3) Temperature sensor An example of a temperature sensor will be described.

FIG. 3 shows an example of an alert circuit as a temperature sensor. The variable current source 18 generates a current I × n and supplies it to a resistor (eg, polysilicon resistor, diffusion resistor, etc.) R. A reference voltage Vref is generated by the variable current source 18 and the resistor R. Trimming of the alert circuit is performed, for example, by changing the value of the current I × n based on the trimming value.

The variable current source 18 is composed of, for example, n MOS transistors connected in parallel. In this case, the value of the reference voltage Vref is trimmed by controlling the on / off of n MOS transistors.

The constant current source 19 generates a current I and supplies it to the diode D. Since the diode D has a threshold value (Vf) characteristic that depends on the chip temperature, the amount of voltage drop changes depending on the chip temperature. Therefore, the output voltage Vf corresponding to the chip temperature is generated.

The voltage comparison circuit 30 includes N-channel MOS transistors Q1 and Q2, constant current sources 19,20,21, a differential amplifier 22 and a buffer 23. The reference voltage Vref is input to the gate of the N-channel MOS transistor Q1, and the output voltage Vf is input to the gate of the N-channel MOS transistor Q2.

The voltage comparison circuit 30 is an example, and a voltage comparison circuit having a configuration other than this can also be used.

When the chip temperature is lower than the alert point, Vref &lt;Vf, so the output signal Alert of the alert circuit is L. Further, when the chip temperature is higher than the alert point, Vref&gt; Vf, so that the output signal Alert of the alert circuit is H.

According to such an alert circuit, it is possible to detect whether or not the chip temperature exceeds the alert point by comparing the output voltage Vf of the diode D having temperature dependence with the reference voltage Vref having no temperature dependence. ..

Here, as shown in FIG. 4, in the case of the temperature sensor using OTD, in order to detect the chip temperature using the voltage difference ΔVeb between the two current values I1 and I2, the characteristic fluctuation of the temperature sensor, That is, there is little variation in the characteristics of the temperature sensor in the initial state (initial) and in the state (after stress) after a certain period of time has elapsed.

Therefore, OTD is used to detect the chip temperature required for updating the trimming value according to the example of the present invention.

On the other hand, as shown in FIG. 5, in the case of the temperature sensor using the alert circuit, in order to detect the chip temperature using the voltage value (absolute value) for one current value Ics, the temperature sensor The characteristic fluctuation, that is, the characteristic fluctuation in the initial state and the characteristic fluctuation of the temperature sensor in the after stress after a certain period of time is large.

The characteristic fluctuation of the alert circuit is due to the following causes.

Fluctuation 1 is a characteristic fluctuation that accompanies a change in the resistance value of resistance R over time. When the resistance value of the resistor R changes, the reference voltage Vref changes.

Fluctuation 2 is a characteristic fluctuation that accompanies a change in the characteristics of the diode D over time. When the characteristics of the diode D change, the relationship between the chip temperature and the output voltage Vf in the diode D changes.

Fluctuation 3 is a characteristic fluctuation due to the reference voltage Vref being constantly applied to the gate of the N-channel MOS transistor Q1. Fluctuation 4 is a characteristic fluctuation due to the output voltage Vf being applied to the gate of the N-channel MOS transistor Q1. Further, the offset voltage of the differential pair fluctuates due to an unbalanced addition (stress) applied to the differential pair of the N-channel MOS transistors Q1 and Q2.

According to the example of the present invention, even if such a characteristic fluctuation of the temperature sensor occurs after the chip is shipped, the accurate chip temperature can always be detected by updating the trimming value of the temperature sensor.

In this way, even when a temperature sensor such as an alert circuit that has a large change in characteristics with time after shipment is used, this is used in combination with a temperature sensor such as OTD that has a small change in characteristics after shipment. However, if the former is compensated by the latter, more accurate chip temperature can be detected.

It should be noted that the temperature sensor whose characteristics change with time after shipment is not limited to the alert circuit, and similarly, the temperature sensor whose characteristics change with time after shipment is not limited to OTD. Absent.

(4) Temperature control method The temperature control method using the temperature control system shown in Fig. 1 or Fig. 2 will be described.

Pre-shipment preparatory work Figure 6 shows the pre-shipment preparatory work for chips.

First, the manufacturer designs and manufactures the chip (step ST1).

In addition, calibration is performed under two temperature conditions (points A and B), the characteristics of the temperature sensor are confirmed, and this is stored as trimming information in a non-volatile memory such as a fuse box (steps ST2 to ST3).

For example, as shown by symbol 1 in FIG. 8, when the trimming value (for example, 8 bits) of the temperature sensor is determined to be 00000100, this is stored in the non-volatile memory. In addition, the coefficients a0 and b0 in Eq. (A) are stored in the non-volatile memory. However, the trimming value and the coefficient b0 can be stored in the non-volatile memory depending on the calibration after shipment.

After this, the chips are shipped (step ST4).

b. Post-shipment temperature control method Figure 7 shows the post-shipment temperature control method.

First, the chip temperature is detected by OTD at a predetermined time point, for example, when the amount of heat generated in the chip becomes uniform at the time of power-on, clock stop, reset, etc. (step ST1).

This predetermined time point is the same as the predetermined time point when the trimming information is obtained in the preparatory work before shipment.

The reason why the calorific value in the chip becomes uniform is that it is desirable that the temperature difference between the chip temperature of the part where the OTD is arranged and the chip temperature of the part where the alert circuit is arranged is as small as possible. is there.

After that, the characteristic fluctuation of the alert circuit is estimated based on the calibration result (trimming value) of the alert circuit, the temperature information, and the trimming information of the alert circuit before shipment, and a new trimming value of the alert circuit is determined. , Update the trimming value (steps ST2 to ST3).

For example, as shown by arrow 2 in FIG. 8, if the trimming value remains in the initial state 00000100 even though the characteristics of the temperature sensor fluctuate, the alert point is lower than the original value. It becomes C point.

Therefore, as shown by arrow 3 in FIG. 8, a new trimming value 00000010 is set and the trimming value is updated so that the alert point does not change even if the characteristic changes due to aging.

The above temperature control method is an example, and the method of updating the trimming value or the data required for updating the trimming value is not particularly limited.

3. Others According to the example of the present invention, accurate chip temperature can always be detected even if the characteristics of the temperature sensor change with time.

As the fuse box, a laser cut type fuse or an electric fuse (E-fuse) can be used.

Further, the non-volatile memory for storing the trimming information is not limited to the fuse box, and a semiconductor memory such as a flash memory can also be used.

The example of the present invention is not limited to the above-described embodiment, and each component can be modified and embodied without departing from the gist thereof. In addition, various inventions can be constructed by appropriately combining a plurality of components disclosed in the above-described embodiment. For example, some components may be deleted from all the components disclosed in the above-described embodiment, or components of different embodiments may be combined as appropriate.

<figref num="1">The figure which shows the temperature control system which concerns on 1st Embodiment.</figref><figref num="2">The figure which shows the temperature control system which concerns on 2nd Embodiment.</figref><figref num="3">A circuit diagram showing an example of an alert circuit.</figref><figref num="4">The figure which shows the characteristic variation of OTD.</figref><figref num="5">The figure which shows the characteristic variation of an alert circuit.</figref><figref num="6">A flow chart showing preparatory work before shipping.</figref><figref num="7">A flow chart showing a temperature control method after shipment.</figref><figref num="8">The figure which shows the update of a trimming value.</figref>

Code description

11: Chip (semiconductor integrated circuit), 12: Fuse box, 13: Trimming control circuit, 14: Alert circuit, 15: OTD, 16: Temperature detector, 17: System controller, 18: Variable current source, 19,20, 21: Constant current source, 22: Differential amplifier, 23: Buffer, 30: Voltage comparison circuit.