VLSI
Solution
y
VS2000 PRELIMINARY
VS2000
5. VS2000 FUNCTIONAL BLOCKS
5
VS2000 Functional Blocks
Reference
Regulator
Regulator
Regulator
Common
Voltage
Driver
Voltage
Monitor
Stereo
Earphone
Driver
Stereo
DAC
AVDD1
AVDD2
AVDD3
Serial
Data/
Control
Interface
UART
Clock
NAND
Flash
Interface/
General IO
<1.6V
USB
X RAM
X ROM
Y RAM
Y ROM
I RAM
I ROM
VSDSP4
processor
USBP
USPN
XCS/GPIO1[0]
SCLK/GPIO1[1]
SI/GPIO1[2]
SO/GPIO1[3]
RX/GPIO1[5]
TX/GPIO1[4]
XTALO
XTALI
Data/
GPIO0[0...7]
Control/
GPIO0[8...14]
XRESET
TEST
IOVDD
AVDD
CVDD
IOVDD1
IOVDD2
PWRBTN
VHIGH
RCAP
CBUF
RIGHT
LEFT
reset
Figure 2: VS2000 Block Diagram
5.1
Regulator Section
The VHIGH pin in the regulator section is used as a common main power supply for voltage regulation. This
input is connected to three internal regulators, which are activated when the PWRBTN pin is set high for about one
millisecond, so that AVDD starts to rise and reaches about 1.5 V. After the PWRBTN has given this initial start
current, the regulators reach their default voltages even if the PWRBTN is released. VHIGH must be sufficiently
(about 0.3 V) above the highest regulated power (normally AVDD) so that regulation can be properly performed.
The PWRBTN state can also be read by software, so it can be used as one of the user interface buttons.
A power-on reset monitors the core voltage and asserts reset if CVDD drops below 1.6 V. It is also possible to
force a reset by keeping PWRBTN pressed for longer than approximately 5.6 seconds. A watchdog counter and
the XRESET pin can also generate a reset for the device.
Resets do not cause the regulators to shut down, but they restore the default regulator voltages. After boot the
firmware and user software can change the voltages.
Return to power-off is possible only with active software control (VSDSP writes the regulator shutdown bit), or
when VHIGH voltage is removed for a sufficiently long time. In the default firmware player the power button has
to be pressed for 2 seconds to make the software powerdown the system and turn the regulators off.
Version 0.3,
2007-09-05
10
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