TX4939XBG-400 Toshiba, TX4939XBG-400 Datasheet - Page 99

• Manufacturer Part Number: TX4939XBG-400
• Manufacturer: Toshiba

Specifications of TX4939XBG-400

• Cpu Core: TX49/H4 90nm
• Clock Mhz/max Mips: 400/520
• Inst./data Cache: 32KB (4 Way)/32KB (4 Way)
• Tlb: x
• 1cycle Mac: x
• Volts (v): 1.25/2.5/3.3
• Peripherals: DDR, NAND, ATA, ETHERNET, SECURITY, FPU, MMU, SPI, I2S, I2C, PCI, VIDEO, UART, TIMER, RTC
• Companion Chip: TC86C001FG
• Package: PGBA456

CG
Depend on the Source Clock frequency, the Baud Rate Source Clock also varies. The Baud Rate Source Clock is either
14,745,600 Hz or 11,059,200 Hz. Table 5-3 describes the relation between UART Divisor and Baud Rate. In this table,
“UART Divisor” represents the product of prescaler and divisor.
5.3.3. Frequency Error in the Generation of Source Clock out of 20 MHz
Followings are the explanation of the technology of fractional N PLL, which generate 451,584,000 Hz clock (F
Figure 5-4 shows the block diagram of this fractional N PLL.
Rev. 3.1 November 1, 2005
Target =
Actual =
20 MHz
451,584,000 Hz
451,578,947 Hz
14,745,600 Hz
11,059,200 Hz
REF
FBK
PLL
F
F
429
SOURCE
SOURCE
19
Table 5-3 Corresponding Prescaler value for each source clock.
OUT
-11.2 PPM
0 PPM
Figure 5-4 Block Diagram of Fractional N PLL
BAUD RATE
BAUD RATE
921,600 bps
460,800 bps
230,400 bps
921,600 bps
460,800 bps
230,400 bps
115,200 bps
115,200 bps
57,600 bps
38,400 bps
28,800 bps
14,400 bps
57,600 bps
38,400 bps
28,800 bps
14,400 bps
9,600 bps
4,800 bps
2,400 bps
1,200 bps
9,600 bps
4,800 bps
2,400 bps
1,200 bps
600 bps
300 bps
600 bps
300 bps
147
245
10
16
1
8
5-5
Division
Division
1536
3072
1152
2304
192
384
768
N/A
N/A
144
288
576
16
24
32
64
96
12
18
24
48
72
1
2
4
8
3
6
Target
Actual
Target
Actual
Target
Actual
(=88.199 KHz x 512)
(=95.999 KHz x 512)
(=921.590 KHz x 16)
(=88.2 KHz x 512)
(=96.0 KHz x 512)
(=921.6 KHz x 16)
Pre-scalar
Bypass pre-scalar and divider
Pre-scalar
45,158,400 Hz
45,157,895 Hz
49,152,000 Hz
49,151,450 Hz
14,745,600 Hz
14,745,435 Hz
1/32
1/32
N/A
N/A
N/A
1/2
1/2
1/2
1/2
1/2
1/2
1/2
1/2
1/2
1/2
1/8
1/8
1/2
1/2
1/2
1/2
1/2
1/2
1/2
1/2
1/8
1/8
Toshiba RISC Processor
Divisor
Divisor
192
192
N/A
N/A
N/A
144
144
12
16
32
48
96
96
96
12
24
36
72
72
72
1
2
4
8
3
6
9
n: numerator
d: denominator
Multiply-Divider
= multiplier
= divider
LEGEND
Digital
n
d
SOURCE
TX4939
).
5
5
5
5