Apple engineers designed the A4 chip with an emphasis on being "extremely powerful yet extremely power efficient." using performance enhancements developed by chip designer
Intrinsity (which was subsequently acquired by Apple) in collaboration with
Samsung. The resulting CPU, dubbed "
Hummingbird", is able to run at a far higher clock rate than previous Cortex-A8 CPUs while remaining fully compatible with the Cortex-A8 design provided by
ARM. The same Cortex-A8 used in the A4 is also used in Samsung's S5PC110A01 SoC. The A4 also features a single-core
PowerVR SGX535 graphics processing unit (GPU). The die of the A4 takes up 53.3 mm2 of area. The
clock rate of the Cortex-A8 in the A4 used inside the
first-generation iPad is 1
GHz. The clock rate of the Cortex-A8 in the A4 used inside the
iPhone 4 and
fourth-generation iPod Touch is 800 MHz (
underclocked from 1 GHz). It is unknown what the clock rate of the Cortex-A8 in the A4 used inside the
second-generation Apple TV is. The A4 uses the
PoP method of installation to support RAM. The top package of the A4 used inside the first-generation iPad, the fourth-generation iPod Touch, and the second-generation Apple TV contains two 128 MB
LPDDR chips, providing a total of 256 MB of RAM. The top package of the A4 used inside the iPhone 4 contains two 256 MB LPDDR chips, providing a total of 512 MB of RAM. The RAM is connected to the A4 using ARM's 64 bits wide
AMBA 3 AXI bus. == Products featuring the Apple A4 ==