Power control circuit

Abstract

Apparatus for controlling an integrated circuit comprises a power control device for controlling the power to at least part of the integrated circuit, the power control device is connected to a first input, for receiving a power-down signal, and a second input, for receiving a power-up signal, the power control device is adapted to power-up the at least part of the integrated circuit if a power-up signal is received at the second input when the at least part of the integrated circuit is in a powered-down state, and the power control device is further adapted to maintain the at least part of the integrated circuit in the powered-up state regardless of any signal received at the second input when the at least part of the integrated circuit is in a powered-up state, the apparatus is arranged so that the second input is also connected to a component of the integrated circuit and the apparatus comprising means for sending a signal to the component of the integrated circuit via the second input when the at least part of the integrated circuit is in the powered-up state.

1 . Apparatus for controlling an integrated circuit comprising a power control device for controlling the power to at least part of the integrated circuit, the power control device being connected to a first input, for receiving a power-down signal, and a second input, for receiving a power-up signal, the power control device being adapted to power-up the at least part of the integrated circuit if a power-up signal is received at the second input when the at least part of the integrated circuit is in a powered-down state, and the power control device being further adapted to maintain the at least part of the integrated circuit in the powered-up state regardless of any signal received at the second input when the at least part of the integrated circuit is in a powered-up state, the apparatus being arranged so that the second input is also connected to a component of the integrated circuit and the apparatus comprising means for sending a signal to the component of the integrated circuit via the second input when the at least part of the integrated circuit is in the powered-up state. 
   
   
       2 . Apparatus according to  claim 1 , wherein the at least part of the integrated circuit comprises digital control circuitry, and preferably the digital control circuitry comprises a serial interface. 
   
   
       3 . Apparatus according to  claim 2 , wherein the first input is connected to the serial interface. 
   
   
       4 . Apparatus according to  claim 2 , wherein the second input is connected to an external control line separate from the serial interface. 
   
   
       5 . Apparatus for controlling an integrated circuit, the integrated circuit comprising digital control circuitry, and the digital control circuitry comprising a serial interface, the apparatus comprising a power control device, the power control device being connected to a first input, for receiving a power-down signal, and a second input, for receiving a power-up signal, the power control device being adapted to power-down the digital control circuitry in response to the power-down signal and to power-up the digital control circuitry in response to the power-up signal, wherein the apparatus is arranged so that the power-down signal is sent to the first input via the serial interface and the power-up signal is sent to the second input via an external control line separate from the serial interface. 
   
   
       6 . Apparatus according to  claim 1 , wherein the power control device comprises a latch circuit and the first input and the second input are each connected to the latch circuit. 
   
   
       7 . Apparatus according to  claim 6 , wherein the latch circuit comprises a set-reset latch circuit and the first input is connected to the set input of the latch circuit and the second input is connected to the reset input of the latch circuit. 
   
   
       8 . Apparatus according to  claim 6 , wherein the power control device is adapted to generate a power-down signal at a second output of the latch circuit in response to receipt of a power-down signal at the first input, and to generate a power-up signal at a first output of the latch circuit in response to receipt of a power-up signal at the second input when the at least part of the integrated circuit is in the powered-down state. 
   
   
       9 . Apparatus according to  claim 8 , wherein the first output of the latch circuit and the second output of the latch circuit are each connected to a power regulation circuit for regulating power from a power source, and the power control device is adapted to control the power to the at least part of the integrated circuit by controlling the power regulation circuit. 
   
   
       10 . Apparatus according to  claim 1 , wherein the power control device is included in the integrated circuit. 
   
   
       11 . Apparatus according to  claim 1 , wherein the at least part of the integrated circuit comprises digital control circuitry, and the digital control circuitry is adapted to control the powering down of analogue circuitry included in the integrated circuit. 
   
   
       12 . Apparatus for controlling an integrated circuit, comprising a power source for powering at least analogue circuitry included in the integrated circuit, a power-down circuit for powering down the analogue circuitry, and digital control circuitry adapted to control the powering down of the analogue circuitry by sending a control signal to the power-down circuit, the digital control circuitry also being adapted to power-down, wherein the apparatus further comprises switching means arranged so as to be closed when the digital control circuitry is powered down and when closed to connect the power source to the power down circuit so as to ensure that the analogue circuitry remains in a powered-down state. 
   
   
       13 . Apparatus according to  claim 12 , wherein the digital control circuitry is adapted to send the control signal to the power-down circuit via a level shift circuit. 
   
   
       14 . Apparatus according to  claim 13 , wherein the switching means is adapted, when closed, to connect the power source to the output of the level shift circuit. 
   
   
       15 . Apparatus according to  claim 12 , wherein the switching means is adapted to close in dependence upon an output signal from a power control device. 
   
   
       16 . Apparatus according to  claim 15 , wherein the digital control circuitry is adapted to receive an external signal and to power down the analogue circuitry upon receipt of the external signal, and preferably the external signal is received via a serial interface. 
   
   
       17 . Apparatus according to  claim 16 , wherein the power control device is also adapted to receive the external signal, and preferably the power control device is adapted to power down the digital control circuitry upon receipt of the external signal. 
   
   
       18 . Apparatus according to  claim 17 , wherein the switching means is adapted to open in dependence upon a further output signal from the power control device, and the digital control circuitry is adapted to power-up in dependence upon the further output signal from the power control device. 
   
   
       19 . Apparatus according to  claim 18 , wherein the power control device is adapted to receive a further external signal and to generate the further output signal upon receipt of the further external signal. 
   
   
       20 . Apparatus according to  claim 19 , wherein the power control device is connected to an external control line separate from the serial interface and is adapted to receive the further external signal via the external control line. 
   
   
       21 . Apparatus according to  claim 20 , wherein the power control device comprises a latch circuit and preferably the output signal is output from a first output of the latch circuit and the further output signal is output from a second output of the latch circuit. 
   
   
       22 . (canceled) 
   
   
       23 . A method of controlling an integrated circuit, comprising providing a power control device for controlling the power to at least part of the integrated circuit, receiving a power-up signal at the power control device via an input and powering-up the at least part of the integrated circuit if the at least part of the integrated circuit is in a powered-down state, and maintaining the at least part of the integrated circuit in the powered-up state regardless of any signal received via the input when the at least part of the integrated circuit is in a powered-up state, the method further comprising sending a signal to a component of the integrated circuit via the input when the at least part of the integrated circuit is in the powered-up state. 
   
   
       24 . A method of controlling an integrated circuit, the integrated circuit comprising digital control circuitry, and the digital control circuitry comprising a serial interface, the method comprising powering-down the digital control circuitry in response to a power-down signal and powering-up the digital control circuitry in response to a power-up signal, the method further comprising sending the power-down signal via the serial interface and sending the power-up signal via an external control line separate from the serial interface. 
   
   
       25 . A method of controlling an integrated circuit, the integrated circuit comprising analogue circuitry, a power-down circuit for powering down the analogue circuitry, and digital control circuitry adapted to control the powering down of the analogue circuitry, the method comprising sending a control signal to the power-down circuit via the digital control circuitry to power down the analogue circuitry, powering down the digital control circuitry, and connecting a power source to the power-down circuitry so as to maintain the analogue circuitry in a powered-down state when the digital control circuitry is powered down. 
   
   
       26 . (canceled) 
   
   
       27 . (canceled)