JP4555167B2 - Power-on control system - Google Patents

Description

  The present invention relates to a power-on control system for an electronic device having circuit blocks that operate with different power supply voltages.

  For example, when a plurality of different power supply voltages are required in one LSI, there are LSIs in which the supply order of different power supply voltages is not restricted, while there are other LSIs in which the supply order of power supplies is restricted. That is, there are LSIs that should supply a high power supply voltage and a low power supply voltage at the same time, and LSIs that supply a low power supply voltage after supplying a high power supply voltage, or supply a high power supply voltage after supplying a low power supply voltage. Exists. Among them, for the LSI with the restriction on the supply voltage supply order, such as the latter, a rule that the time difference of the supply voltage supply must be a certain value or less is specified as the LSI specification.

  Conventionally, this type of power-on control system has a power-on condition different from the initial power-on condition when the apparatus does not start up normally even when the power is turned on and the power is turned on again (for example, Patent Document 1). reference). The power-on condition when assuming two types of power supply voltages is determined by a combination of four parameters indicating whether or not the power supply voltage is delayed and whether or not the rise of the power supply voltage is dull 16 It becomes as follows.

  Sequentially turn on the power under these power-on conditions, and even if there are critical factors such as the power-on voltage turn-on sequence, variation in LSI characteristics, and differences in the usage environment, the device is reliably brought up to a normal state. Make it possible.

JP 2002-176777 (first page to second page, FIGS. 1 and 6)

  However, with the above-described conventional technology, it is necessary to turn on the power a plurality of times until a normal result is obtained, but for LSIs and the like in which the power supply order is limited, in order to obtain appropriate parameters There is a first problem that multiple power-on attempts may cause fatal damage to the LSI itself, and in the worst case, the LSI may be damaged.

  The second problem is that a parameter corresponding to the load must be redetected every time the load of the power supply voltage supply destination changes.

  Accordingly, an object of the present invention is to provide a power-on control system in which an appropriate power-on sequence corresponding to a load is determined by only one power-on, and the power control system is highly reliable and simplified. It is in.

  The power-on control system of the present invention includes a power switch (6, 7 in FIG. 1) and a power supply voltage monitoring circuit (16, 17 in FIG. 1) for monitoring the power supply voltage (11, 12 in FIG. 1) output from the power switch. The rise time calculation circuit (20, 21 in FIG. 1) for calculating the rise time of the power supply voltage, the power switch time of the power switch at the timing suitable for the system from the power-on time desired by the user and the rise time obtained by the rise time calculation circuit It consists of a power-on sequence determination circuit (10 in FIG. 1) that performs ON / OFF.

In general, the rising characteristic of the power supply voltage varies depending on the size of the load connected to the power supply. When the load is large (heavy), the time required to reach the specified power supply voltage becomes longer, and when the load is light, the time becomes shorter. Therefore, a power supply voltage monitoring circuit for monitoring the power supply voltage supplied to each load is provided, and the rise time calculation circuit calculates the time required to reach a specified voltage (effective for the load).

The turn-on order determination circuit determines the timing for turning on the power switch from the rise time signal output from the rise time calculation circuit and the value of the power supply voltage turn-on time defined by the load 13 (24 in FIG. 1). In this way, the optimal power-on timing for the system can be determined in a single trial.

The first effect of the present invention is that a power-on sequence control system that does not depend on the size (weight) of the load can be constructed with a single power-on trial. The reason for this is that the power-on result is monitored by the power-supply voltage monitoring circuit, and the rise time difference of the power-supply voltage output from the rise-time calculating circuit is fed back to the power-on timing based on this monitoring result.

  The second effect of the present invention is that it is possible to construct a power-on sequence control system that responds quickly to changes in the usage environment. This is because the result of power-on is fed back to the power-on timing, so that the power-on sequence can be determined by compensating for the power-up characteristics corresponding to the fluctuations in the usage environment.

A power-on control system according to the present invention is a power-on control system for an electronic device having a circuit block that operates at different power supply voltages. The power switch corresponding to the power voltage, a power voltage monitoring circuit, a rise time calculation circuit , And an order determination circuit.

The power switch turns on / off the input power supply voltage and supplies it to the load. The power supply voltage monitoring circuit monitors the rise time of the power supply voltage output from the power switch. The rise time calculation circuit calculates the rise time until the power supply voltage reaches a specified voltage effective for the load based on the monitoring result, and outputs a rise time signal representing the rise time. The power-on sequence determination circuit is set with the power supply voltage power-on time difference value specified for the load, and each rise time difference represented by the rise-time signal falls within the set power-up time difference. Determine when to turn on the power switch.

Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a configuration diagram of a power-on control system to which the present invention is applied. This power-on control system generates two secondary power supply voltages 4 and 5 from the primary power supply voltages 1 and 3 and supplies them to power supply circuits 14 and 15 of a load 13 such as an LSI that operates at different power supply voltages. To do.

In FIG. 1, a primary power supply voltage 1 is connected to a power supply 2 and a turn-on order determination circuit 10. When the primary power supply voltage 1 is supplied, the power supply 2 outputs secondary power supply voltages 4 and 5. The secondary power supply voltage 4 is connected to the power switch 6, and the secondary power supply voltage 5 is connected to the power switch 7.

  The output of the power switch 6 is controlled by the ON / OFF signal 8 output from the input sequence determining circuit 10, and the power supply voltage 11 becomes the same voltage as the secondary power supply voltage 4 when the ON / OFF signal 8 is ON. . The power supply voltage monitoring circuit 16 monitors the power supply voltage 11, and after the power switch 6 is turned ON, the power supply voltage 11 (which becomes an effective power supply voltage for the load 13) reaches a specified voltage, and a specified voltage pulse 18 is output.

  Similarly, the output of the power switch 7 is controlled by the ON / OFF signal 9 output from the input sequence determining circuit 10, and the power supply voltage 12 is the same as the secondary power supply voltage 5 when the ON / OFF signal 9 is ON. Become a voltage. The power supply voltage monitoring circuit 17 monitors the power supply voltage 12, and after the power switch 7 is turned ON, the power supply voltage 12 (which becomes an effective power supply voltage for the load 13) reaches the specified voltage pulse. 19 is output. These states are shown in a waveform diagram in FIG.

Upon receiving the specified voltage pulse 18, the rise time calculation circuit 20 sends a rise time signal 22 corresponding to the time width to the input sequence determination circuit 10. Similarly, upon receiving the specified voltage pulse 19, the rise time calculation circuit 21 sends a rise time signal 23 corresponding to the time width to the input sequence determination circuit 10.

In the turn-on order determination circuit 10, a power-on time difference 24 between the power supply circuit 14 and the power supply circuit 15 defined by the load 13 is set by the user. The turn-on sequence determination circuit 10 compares the power-on time difference 24 with the difference between the rise time represented by the rise time signal 22 and the rise time represented by the rise time signal 23, and the result matches the latter with the former. The ON / OFF signals 8 and 9 are output so that the The timing for sending the ON / OFF signals 8 and 9 starts from the primary input voltage 3.
[Description of operation]
Next, a method for controlling the power-on sequence according to the present invention will be described. In FIG. 1, when the primary power supply voltage 1 is turned on after the load 13 is connected, the turn-on order decision circuit 10 outputs ON / OFF signals 8 and 9 for turning the power switches 6 and 7 from OFF to ON simultaneously. To do. This is the first power-on.

  The power switches 6 and 7 start outputting when the ON / OFF signals 8 and 9 are input. At this time, the power supply voltage depends on the size (weight) of the load connected to the power switches 6 and 7. The transition times (rise times) of 11 and 12 are different. This is shown in FIGS. Note that the loads connected to the power switches 6 and 7 mean not only the load 13 but also all the loads for the outputs of the power switches 6 and 7 including wiring and the like.

  FIG. 2 shows a case where the load on the power switch 6 side is smaller than the load on the power switch 7 side, and it can be seen that the power supply voltage 11 reaches the specified voltage earlier than the power supply voltage 12. On the other hand, FIG. 3 shows a case where the load on the power switch 6 side is larger than the load on the power switch 7 side. The power supply voltage 12 reaches the specified voltage earlier than the power supply voltage 11. I understand.

The power supply voltage monitoring circuits 16 and 17 output specified voltage pulses 18 and 19 corresponding to the rise times of the power supply voltages 11 and 12, as shown in FIG. The rise time difference calculation circuits 20 and 21 output rise time signals 22 and 23 corresponding to the pulse widths of the specified voltage pulses 18 and 19, respectively. FIG. 5 shows the situation when the load on the power switch 6 side shown in FIG. 2 is light. In the example of FIG. 5, if the power supply rise time on the power switch 6 side is 10 msec and the power supply rise time on the power switch 7 side is 20 msec, these values of 10 msec and 20 msec are input to the input sequence determination circuit 10 as rise time signals 22 and 23. Is done.

  In the turn-on order determination circuit 10, a prescribed value of the power-on time difference 24 prescribed for the power supply circuit 14 and the power supply circuit 15 of the load 13 is preset by the user. The specified value of the power-on time difference 24 is, for example, that the power supply voltage 12 becomes the specified voltage 30 msec after the power supply voltage 11 reaches the specified voltage.

  FIG. 6 shows how the power supply voltages 11 and 12 rise when the power switches 6 and 7 are simultaneously turned ON. In FIG. 6, since the power supply voltage 12 reaches the specified voltage 10 msec after the power supply voltage 11 reaches the specified voltage, the specified value in the above example is not satisfied.

  In order to compensate for this, the power switch 12 must be turned on 30 msec−10 msec = 20 msec after the power switch 11 is turned on. That is, the input sequence determination circuit 10 sends an ON / OFF signal 9 for turning on the power switch 12 after 20 msec after sending the ON / OFF signal 8 for turning on the power switch 6. This is the second power-on. By performing such control, it is possible to control the power-on sequence specified for the load 13. This is shown in FIG.

  As described above, the turn-on order determination circuit 10 performs appropriate power-on by feeding back the power supply voltage rising characteristics according to the load. Especially in systems where the power is frequently turned on and off, by performing this feedback operation every time, it is possible to follow changes in the power-up characteristics due to environmental conditions such as ambient temperature, and always adapts to the situation. This makes it possible to construct a power-on sequence control system.

  In order to simplify the explanation, the load 13 has been described as having only two power supply circuits 14 and 15. However, even if the load 13 has three or more power supply circuits whose turn-on order is restricted. Of course it is good. In that case, the switch, the power supply voltage monitoring circuit, and the rise time calculation circuit are provided as many as the number of power supply voltages subject to the turn-on control, and the power-on time difference 24 is also set by that number.

Block diagram of a power-on control system according to the present invention Waveform diagram showing rise characteristic example 1 of power supply voltage Waveform chart showing power supply voltage rise characteristic example 2 Waveform diagram showing generation of specified voltage pulse in the present invention Waveform showing generation of rise time signal in the present invention The waveform diagram which illustrates the rise time difference of the power supply voltage according to the weight of the load in the present invention Waveform diagram showing how the rise time difference of the power supply voltage due to the weight of the load is compensated according to the present invention

Explanation of symbols

1,3 Primary power supply voltage 2 Power supply 4,5 Secondary power supply voltage 6,7 Power switch 8,9 ON / OFF signal
10 Input sequence determination circuit
11, 12 Supply voltage
13 Load
14, 15 Power circuit
16, 17 Supply voltage monitoring circuit
18, 19 Specified voltage pulse
20, 21 Rise time calculation circuit
22, 23 Rise time signal
24 Power-on time difference

Claims (2)

In a power-on control system for an electronic device having a circuit block that operates with different power supply voltages,
A power switch corresponding to the power supply voltage to supply the load by turning ON / OFF the input power supply voltage;
A power supply voltage monitoring circuit corresponding to the power supply voltage for monitoring a rise time of a power supply voltage output from the power switch;
A rise time calculation circuit corresponding to the power supply voltage for calculating a rise time until the power supply voltage reaches a specified voltage effective for the load according to a result of the monitoring, and outputting a rise time signal representing the rise time ; ,
The power supply voltage input time difference value specified for the load is set, and the timing for turning on each of the power switches is determined so that the rise time difference falls within the set input time difference. A power-on control system, comprising: The power supply voltage monitoring circuit is a specified voltage having a pulse width that is a time from when the power switch is turned on by the turn-on order determining circuit until the rising of the power supply voltage reaches a specified voltage effective for the load. Output a pulse,
The power-on control system according to claim 1, wherein the rise time calculation circuit outputs the rise time signal according to a pulse width of the specified voltage pulse.

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