JP2003215214A - Semiconductor integrated circuit device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor integrated circuit device which prevents operating function blocks from malfunctioning without almost increasing the scale of a circuit which realizes the function of holding the output data of a functional block, when power supply to the function block is interrupted. <P>SOLUTION: A circuit block 100 is connected between the output terminal of the function block whose power interruption is performed and the input terminal of a function block whose power interruption is not performed. The circuit block 100 is provided with a selector 111 which selects an input data DIN or serial data SDIN from the function block whose power interruption is performed when a power interruption signal POFF is a signal representing a power supplying state, selects a held data held by a flip-flop 109 when power supply is interrupted, and outputs it to the operating function blocks when the power interruption signal is a signal representing a power interrupted state on the other hand. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor integrated circuit device, and more particularly to a semiconductor integrated circuit device having a power cutoff function.

[0002]

2. Description of the Related Art One of the technical problems in recent semiconductor integrated circuit devices is to reduce power consumption when a functional block in a semiconductor integrated circuit is in a standby state.
Conventionally, various measures have been taken to reduce power consumption, but a typical method is to stop the clock supplied to the inside of the functional block.

However, the off-leakage current of a transistor is increasing with the miniaturization of the process. Therefore, even if the internal clock of the functional block in the standby state is stopped, the power consumption due to the off-leakage current increases, and the power consumption reduction effect is becoming insufficient. As one of the methods for solving this, there is a means for cutting off the power supply to the functional block in the standby state. This is to cut off the power supply to eliminate the off-leakage current of the transistors in the functional block and reduce the power consumption.

As described above, a problem when the power supply to the functional block is cut off is a signal connected from the functional block that cuts off the power to the functional block that does not cut off the power. This signal becomes a floating state in terms of voltage when the functional block is in the power-off state, so the input gate of the functional block that receives this signal and does not perform power-off becomes floating, and as a result, its input gate It will cause a leak in the.

For this reason, conventionally, as shown in FIG. 4A, the voltage fixing circuit 403 is provided between the output terminal of the functional block 401 that cuts off the power and the input terminal of the functional block 402 that does not cut off the power. This voltage fixing circuit 4
03 is a power-off signal PO of logic "0" at power-off
By fixing the signal voltage to the functional block 402 to the ground level (logic “0”) by the FF, it is possible to prevent the input gate of the functional block 402 that does not perform power shutoff from floating. The voltage fixing circuit 403 shown in FIG. 4B is configured by an AND circuit as an example. However, by configuring the voltage fixing circuit 403 by an OR circuit, the functional block 4 is activated by the power cutoff signal POFF of logic “1”.
It is also possible to fix the signal voltage to 02 to the power supply voltage level (logic "1").

Also, in a processing device such as a processor, when a certain functional block does not need to operate while a certain instruction is being executed, the power supply to the functional block that does not require the operation is shut off in the same manner as described above. To reduce power consumption. However, when the voltage fixing circuit 403 fixes the output signal to either the power supply voltage level or the ground level, the output signal of the functional block 401 whose power supply is cut off is controlled by the functional block 402 which does not cut off the power supply. When used as a signal or the like, the logic of the control signal changes when the power is cut off, which may cause the functional block 402 to malfunction. Therefore, by adding a data holding circuit that holds the logic of the control signal before the power is cut off, even if the power of a certain function block is cut off, the function block in operation does not malfunction. .

By the way, recently, JTAG (Joint Test A
ction group) and IEEE Standard 1149.1-
1990 Standard (IEEE Standard Test Access Port and Bounda
Boundary scan circuit, which is standardized as ry scan architecture, is implemented, and the logical level of the signal is arbitrarily given to the input of the functional block by serial data, and the output result can be monitored and the output signal during operation can be monitored. Generally, a semiconductor integrated circuit device capable of monitoring the state and performing various tests and debugs is designed and manufactured.

As is well known, in the boundary scan method, for example, as shown in FIG. 5, an input terminal 50 of a functional block 500 in a semiconductor integrated circuit is used.
1. A shift register called “cell” is arranged between the output terminal 502 and another functional block or device terminal to monitor a signal passing through the cell 503 or
It is possible to set the value for 03
Boundary scan register is a series connection of 3's. In FIG. 5, reference numeral 504 is a TAP (test access point) controller, which is a sequential circuit (state machine) that controls the boundary scan.

[0009]

However, when powering down the functional block having the boundary scan register as described above, a voltage fixing circuit or a data holding circuit at the time of powering down is further provided around the boundary scan register. Must be placed, and as a result,
The circuit scale will increase.

Further, in a processing device such as a processor, when power is supplied to a functional block and then restored, the functional block that has been powered off initializes its internal logic and returns. For this reason, the output data changes to the signal logic of the initial state at the same time when the power supply is started only with the conventional data holding circuit at the time of power shutoff, which is the control signal to the functional block in the peripheral operation state. In such a case, it may cause a malfunction.

The present invention has been made in view of the above problems, and an object thereof is a circuit that realizes a function of holding output data of a functional block having a boundary scan register when the power is cut off. The semiconductor that does not malfunction even if the logic of the output signal from the function block that was shutting down the power supply changes to the initial state when the power supply is started. An object is to provide an integrated circuit device.

[0012]

In order to achieve the above-mentioned object, a first semiconductor integrated circuit device according to the present invention has an output terminal of a first functional block to which power is supplied / interrupted and a power supply. It is connected between the input terminal of the second functional block that is not interrupted, receives the output data from the output terminal of the first functional block, and outputs it to the input terminal of the second functional block. 1. A semiconductor integrated circuit device having a plurality of circuit blocks for sequentially performing a boundary scan by sequentially transferring the serial data held in each of the plurality of circuit blocks, wherein each of the plurality of circuit blocks is a power-off signal or a serial transfer signal indicating a power supply / interruption state. A latch circuit that latches and holds output data or serial data from the output terminal of the first functional block according to the clock signal for power supply When the supply state is indicated, the output data or serial data from the output terminal of the first functional block is selected. On the other hand, when the power cutoff signal indicates the power cutoff state, the holding data held by the latch circuit at the time of the power cutoff And a selection circuit for selecting and outputting to the second functional block.

According to this configuration, when the power supply to the functional block having the boundary scan circuit connected to the output terminal is cut off, the operation block using the output signal from the functional block malfunctions. The output data holding function for preventing the occurrence of the above can be realized with almost no increase in the circuit scale.

In order to achieve the above-mentioned object, a second semiconductor integrated circuit device according to the present invention has an output terminal of a first functional block to which power is supplied / interrupted and a power supply not interrupted. It is connected between the input terminal of the second functional block, receives the output data from the output terminal of the first functional block, outputs it to the input terminal of the second functional block, and holds the output data internally. A semiconductor integrated circuit device having a circuit block, wherein the circuit block latches and holds output data from an output terminal of the first functional block in response to a power cutoff signal indicating a power supply / interruption state. Select the output data from the output terminal of the first functional block when the circuit and the power cutoff signal indicate the power supply state, while the power cutoff signal is selected when the power cutoff signal indicates the power cut state. A selection circuit for selecting the held data held by the latch circuit and outputting it to the second functional block when the power cutoff signal changes from the power cutoff state to the supply state; The data held in the latch circuit is selected until the output data from the first functional block is updated, and when the output data is updated in the first functional block, the output from the output terminal of the first functional block Characterized by selecting data.

According to this structure, when the power is restored, the output from the functional block is switched by synchronizing the update timing of the output signal from the functional block and switching from the held data before the power shutdown to the updated data. A malfunction can be suppressed for an operation block using a signal.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be specifically described below with reference to the drawings.

(First Embodiment) FIG. 1 shows a first embodiment of the present invention.
3 is a circuit diagram showing a partial configuration of a semiconductor integrated circuit device having a boundary scan function according to the embodiment of FIG. The circuit block 100 of FIG. 1 is connected between an output terminal of a functional block (not shown) to which power is supplied / cut off and an input terminal of a functional block (not shown) to which power is not cut off.

This circuit block 100 is connected as a connection terminal to the output terminal of the functional block whose power is cut off in the standby state, and the data input terminal 101 for input data (DIN) and the serial data (SDIN) are input. A serial data input terminal 102, a terminal 103 to which a serial clock (SCLK) is input, and a terminal 104 to which a power cutoff signal (POFF: “0” when power is supplied, “1” when power is cut off) are input. Connected to the terminal 105 to which the serial transfer mode signal (STMODE) is input and the input terminal of the functional block whose power is not cut off,
A data output terminal 106 for output data (DOUT).

Further, the circuit block 100 has a selector 107 (SMODE = “0”) which selectively outputs the input data DIN or the serial data SDIN according to the serial transfer mode signal STMODE.
N, SMODE = “1” selects SDIN), and a selector 108 that selectively outputs the power-off signal POFF or the serial clock SCLK according to the serial transfer mode signal STMODE (SMODE = “0” POFF,
SMODE = “1” selects SCLK) and selector 1
Flip-flop 109 that latches and holds the output data from 07 at the rising edge of the output signal (ICLK) from selector 108, OR circuit 110 that ORs power-off signal POFF and serial mode transfer signal STMODE, and OR Output signal from circuit 110 (OROU
Selector 111 (OROUT = “0” (POFF and S) that selectively outputs input data DIN or output data (FOUT) from flip-flop 109 according to T).
When both TMODEs are "0"), DIN and OROUT =
"1" (Either POFF or STMODE is "1")
And select FOUT).

Next, the operation of the circuit block 100 thus configured will be described.

In normal operation, power is supplied to the functional block for supplying / shutting off power, that is, the power shutoff signal POFF is "0" (ground level) and the serial transfer mode signal STMODE is "0". If there is
The input data DIN from the data input terminal is the selector 1
11 is selected and the output data D is output to the data output terminal 106.
It is output as OUT.

Here, when the functional block for supplying / shutting off the power supply is in a standby state, the power supply to it is shut off, that is, the serial transfer mode signal STMOD.
When E is "0" and the power cutoff signal POFF changes from "0" to "1" (power supply voltage level), the flip-flop 109 latches and holds the logic of the input data DIN, and at the same time, the selector. 111 selects the output data FOUT of the flip-flop 109 and outputs it to the data output terminal 106.

Thereafter, the flip-flop 1 is turned on while the power is cut off.
The data held in 09 continues to be output, and the signal logic to the other operation blocks can maintain the state before the power-off.

When the boundary scan function is used for debugging or test operation, that is, the power cutoff signal POFF is "0" and the serial transfer mode signal ST
When MODE is “1”, the selector 107 selects the serial data SDIN, the selector 108 selects the serial clock SCLK, and the selector 111 selects the output data FOUT of the flip-flop 109, whereby a shift register is provided. Can be operated.

Here, when the power supply is cut off, the state of the data input terminal 101 becomes floating, but the power supply cutoff signal POFF is "1", so the selector 111
Does not select the input data DIN and the flip-flop 10
9 output data FOUT is selected. Therefore, the leak current due to the floating state of the data input terminal 101 does not occur. Further, considering the time from when the power supply is cut off until the input data DIN changes to an indefinite logic, the flip-flop 109 can sufficiently latch the input data DIN before the power supply is cut off.

FIG. 2A is a block diagram showing a modified example of this embodiment, and FIG. 2B is a circuit diagram showing the internal structure of the circuit block 202. 2 (a) and 2
In (b), 201 is a boundary scan circuit, which is provided in the circuit block 100 of FIG.
It is composed of a flip-flop 109 and a selector 111. This is the selector 108, the OR circuit 110, and the system selector 10 in the circuit block 100 of FIG.
Output signal ICLK from 8 to the flip-flop 109,
Output signal ORO from OR circuit 110 to selector 111
UT and serial transfer mode signal STMODE
This is because all boundary scan circuits 201 connected in series around a certain functional block 200 can be shared. Using this, the selector 108 and O
By arranging the R circuit 110 as the control circuit 202 outside the boundary scan circuit 201, the area of the boundary scan circuit portion is reduced.

As described above, according to this embodiment, the function of holding the logic of the output signal from the functional block when the power supply to the functional block is cut off, and the shift register function of the boundary scan, One flip-flop 109 can be shared. Further, since the selector 111 receives the output signal from the functional block, it is not necessary to separately add a circuit in consideration of the floating of the output signal when the power is cut off. As a result, in the semiconductor integrated circuit device having the boundary scan circuit in the periphery of the functional block, it becomes possible to realize the data holding function when the power is cut off, with almost no additional circuit.

(Second Embodiment) FIG. 3 shows a second embodiment of the present invention.
3 is a block diagram showing an example of a partial configuration of the semiconductor integrated circuit device according to the embodiment of FIG. In FIG. 3, the semiconductor integrated circuit device according to the present embodiment includes an output terminal of the functional block 300 to which power is supplied / interrupted and an output terminal of the functional block 300 and a functional block (not shown) in which power is not interrupted. It is composed of a circuit block 301 connected to the input terminal.

The circuit block 301 serves as a connection terminal.
A data input terminal 101 for input data (DIN) and a clock terminal 302 to which a clock signal (CLK) is input.
And a terminal 105 to which a power-off signal (POFF) is input
And a reset terminal 3 to which a reset signal (RS) is input
03 and a data output terminal 1 for output data (DOUT)
06 and.

Further, the circuit block 301 includes a flip-flop 304 which latches and holds the input data DIN when the power cutoff signal POFF changes from "0" to "1" (when the power is cut off). , Function block 3
Clock signal CLK from 00 and power cutoff signal POFF
AND circuit 305 that performs a logical product with the inversion signal of
At the rising edge of the output signal from the D circuit 305, the data “0” at the D input terminal is latched and held, and the power cutoff signal P
When OFF is “1” (power-off state), the flip-flop 306 that outputs “1” and the flip-flop 3
Input data D according to the output signal FOUT2 from 06.
IN or output signal F from flip-flop 304
A selector 307 that selectively outputs OUT1 (FOUT2 =
Select "0" for DIN, FOUT2 = "1" for FOUT
1 is selected).

Further, the functional block 300 outputs the system clock (SCLK) to the clock signal CLK when the enable signal (EN) is "1" and the flip-flop group 308 and the combinational circuit 309 which generate the logic of the input data DIN. To the circuit block 301 and to the flip-flop group 308 as the clock signal CLK.
And an AND circuit for outputting.

Next, the operation of the circuit block 301 thus configured will be described.

In the normal operation after the reset start, when the power is supplied to the functional block 300, that is, when the power cutoff signal POFF is "0" and the output signal FOUT2 of the flip-flop 306 is "0", the input is made. The data DIN is selected by the selector 307 and output to the data output terminal 106 as output data DOUT.

Here, when the functional block 300 is in the standby state and shuts off the power supply, that is, the power shutoff signal P.
When OFF changes from "0" to "1", the flip-flop 304 latches and holds the signal logic of the data input DIN, and at the same time, the flip-flop 306 is set to "1" by the power cutoff signal POFF. As a result, the selector 307 receives the output signal FOUT2 of “1” from the flip-flop 306, selects the output signal FOUT1 from the flip-flop 304, and outputs it as the output data DOUT to the data output terminal 106.

After that, the data output terminal 10 is operated while the power is cut off.
From 6, the data held in the flip-flop 304 continues to be output, and the signal logic to other operation blocks can maintain the state before power-off.

Next, when power is supplied and the functional block 300 that has been shut down is restored, that is, when the power shutoff signal POFF changes from "1" to "0", the clock of the flip-flop 304 becomes "0". However, since there is no change in operation of the selector 307 and the flip-flop 306, the data held in the flip-flop 304 continues to be output from the data output terminal 106 as it is.

After that, when the functional block 300 starts to operate and the data held in the flip-flop group 308 which generates the logic of the input data DIN is updated, that is, the clock signal CLK to the flip-flop group 308 is "0".
When it changes from “1” to “1”, in the circuit block 301, the clock signal CLK is supplied to the flip-flop 306 via the AND circuit 305, and the flip-flop 30
The output signal FOUT2 of 6 is updated to "0" at the same time.
As a result, the selector 307 selects the input data DIN, the logic of the output signal from the functional block 300 is output to the data output terminal 106, and the data is updated at the timing to be updated.

Here, when the power supply is cut off, the state of the data input terminal 101 becomes floating, but since the power supply cutoff signal POFF is "1", the selector 307 is selected.
Does not select the input data DIN and the flip-flop 30
4 output data FOUT1 is selected. For this reason,
Leakage current due to the floating state of the data input terminal 101 does not occur. Further, since the power cutoff signal POFF is “1”, the flip-flop 304 is configured by connecting a tri-state inverter or the like to the data input terminal (D) therein. This allows
It is possible to avoid the occurrence of leakage current. Further, as a method of generating the clock signal CLK for updating the logic of the output signal of the functional block 300, another method may be used.

As described above, according to the present embodiment, when the power supply to the functional block 300 is cut off, the logic of the output signal from the functional block 300 is held, and the functional block is further supplied by the power supply. Is restored, the function of switching from the signal logic held in the flip-flop 304 to the logic of the output signal from the functional block 300 is realized at the same timing as when the output signal from the functional block 300 is updated. can do. As a result, in a processing device such as a processor, when power is supplied to a functional block again after the power is cut off, the functional block is initialized, and thus it is possible to prevent a signal from changing to a signal logic in an initial state. At the same time, it is possible to avoid the cause of the malfunction occurring in the functional block in operation, which is switched between the hold data before power-off and the output data in synchronization with the update timing of the output signal.

[0040]

As described above, according to the present invention,
Holds output data to prevent malfunctions in the operation block that uses the output signal from the functional block when powering off the functional block to which the boundary scan circuit is connected to the output terminal. The function can be realized with almost no increase in the circuit scale.

Further, when returning from power cutoff, the output signal from the functional block is used by switching from the hold data before power cutoff to the update data in synchronization with the update timing of the output signal from the functional block. It is possible to suppress malfunctions of the operating blocks that are in operation.

Further, it becomes possible to finely control the power supply to the functional block which could not be shut down due to the malfunction of the functional block which is in operation due to the power shutoff, and further low power effect is expected. it can.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a partial configuration of a semiconductor integrated circuit device having a boundary scan function according to a first embodiment of the present invention.

FIG. 2 is a block diagram (a) showing a modified example of the semiconductor integrated circuit device having a boundary scan function according to the first embodiment of the present invention and a circuit diagram showing an internal configuration of a circuit block 202.

FIG. 3 is a block diagram showing a partial configuration example of a semiconductor integrated circuit device according to a second embodiment of the present invention.

FIG. 4 is a block diagram (a) showing a partial configuration of a conventional semiconductor integrated circuit device and a circuit diagram (b) showing an internal configuration of an output voltage fixing circuit 403.

FIG. 5 is a block diagram showing a partial configuration of a conventional semiconductor integrated circuit device having a boundary scan function.

[Explanation of symbols]

100, 201, 301 Circuit block 101 having an output data holding function 101 Data input terminal 102 Serial data input terminal 103 Serial clock input terminal 104 Power cutoff signal input terminal 105 Serial transfer mode signal input terminal 106 Data output terminals 107, 108, 111, 307 selector 109, 304, 306 flip-flop 110 OR circuit 200, 300 functional block 202 in which power is cut off control circuit 302 clock signal input terminal 303 reset signal input terminal 305, 310 AND circuit 308 flip-flop group

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 2G132 AA00 AA15 AC15 AG08 AH04                       AK07 AK09 AL00                 5F038 BH19 CD06 CD16 DF17 DT06                       DT10 EZ20                 5J032 AA00 AB02 AC13                 5J056 AA03 BB21 CC00 CC14 EE08                       FF01 FF07 FF09 GG14

Claims (2)

[Claims] 1. The first function block is connected between an output terminal of a first functional block where power is supplied / cut off and an input terminal of a second functional block where power is not cut off. A semiconductor integrated circuit having a plurality of circuit blocks for receiving output data from an output terminal of the block, outputting the data to an input terminal of the second functional block, and sequentially transferring internally held serial data to perform boundary scan. In the device, each of the plurality of circuit blocks is configured to output data from an output terminal of the first functional block according to a power cutoff signal indicating a power supply / cutoff state or a clock signal for serial transfer. A latch circuit for latching and holding the serial data; and an output terminal of the first functional block if the power cutoff signal indicates a power supply state. Output data or the serial data is selected, and when the power cutoff signal indicates a power cutoff state, the held data held in the latch circuit at the time of power cutoff is selected and the second functional block is selected. A semiconductor integrated circuit device comprising: a selection circuit for outputting. 2. The first function block, which is connected between an output terminal of a first functional block where power is supplied / cut off and an input terminal of a second functional block where power is not cut off. A semiconductor integrated circuit device having a circuit block that receives output data from an output terminal of a block, outputs the data to an input terminal of the second functional block, and holds the output data inside, the circuit block comprising: A latch circuit that latches and holds output data from the output terminal of the first functional block according to a power cutoff signal indicating a power supply / shutdown state; and the power cutoff signal indicates a power supply state In this case, when the output data from the output terminal of the first functional block is selected, while the power cutoff signal indicates a power cutoff state, the data is held by the latch circuit when the power is cut off. A selection circuit for selecting the retained data and outputting it to the second functional block, wherein the selection circuit has the first function when the power cutoff signal changes from a power cutoff state to a supply state. The data held in the latch circuit is selected until the output data from the block is updated, and when the output data from the first functional block is updated, the data from the output terminal of the first functional block is selected. A semiconductor integrated circuit device characterized by selecting output data.