Hardware Reference
In-Depth Information
External
modem or
accelerator
LP Audio back-end
L3
USB-HS
ARMv7
MPU
32KB/32KB L1
1MB L2
64KB.RAM
128KB ROM
Imaging
Extensions
mini64
466MHz
32KB L1
128KB L2
IVA-HD
1080P
256KB SL2
C2C
200MHz
(DDR)
DSS
Display
(DSI/HDMI)
3-port
USB-HS
Host
SGX540
2D/3D
SDMA
ISP5
SIMCOP
UNIPRO
HSI
Ducati
200Mhz
IVA3
SDRC
High bandwidth interconnect with multichannel memory support
DMM
C2C
Crypto
DMA
Security
accelerators
GPMC
external
NAND/NOR
On-chip
L3 RAM
48KB
DAP
Debug
& trace
MMCSD
(w/DMA)
8-bit DDR
Power
Reset
Clocks
Manager
Peripherals
L4
Per/emu/core/ABE
EMIF1
LPDDR2
(400MHz)
EMIF0
LPDDR2
(400MHz)
AES/SHA
Figure 3-47.
The internal organization of the OMAP4430 system-on-a-chip.
The many processors of the OMAP4430 are incorporated specifically to sup-
port its mission of low-power operation. The graphics processor, ISP, and IVA3 are
all programmable accelerators that provide efficient computation capabilities at
significantly less energy compared to the same tasks running on the ARM A9
CPUs alone. Fully powered, the OMAP4430 SoC draws only 600 mW of power.
Compared to a high-end Core i7, the OMAP4430 uses about 1/250 as much power.
The OMAP4430 also implements a very efficient sleep mode; when all compo-
nents are asleep, the design draws only 100
μ
W. Efficient sleep modes are crucial
to mobile applications with long periods of standby time, such as a cell phone. The
less energy used in sleep mode, the longer the cell phone can stay in standby mode.
To further reduce power demands of the OMAP4430, the design incorporates a
variety of power-management facilities, including
dynamic voltage scaling
and
power gating
. Dynamic voltage scaling allows components to run slower at a
lower voltage, which significantly reduces power requirements. If you do not need
the CPU's most blazing speed for computation, the voltage of the design can be
lowered to run the CPU at a slower speed and much energy will be saved. Power
gating is an even more aggressive power-management technique where a compo-
nent is powered down completely when it is not in use, thereby eliminating its
power draw. For example in a tablet application, if the user is not watching a
movie, the IVA3 video processor is completely powered down and draws no power.
Conversely, when the user is watching a movie, the IVA3 video processor is speed-
ing through its video decoding tasks, while the two ARM A9 CPUs are asleep.
