T89C5121-ICUIL Atmel, T89C5121-ICUIL Datasheet - Page 27

• Manufacturer Part Number: T89C5121-ICUIL
• Description: IC 8051 MCU W/SMART CARD 24SSOP
• Manufacturer: Atmel
• Series: 89Cr

Specifications of T89C5121-ICUIL

• Core Processor: 8051
• Core Size: 8-Bit
• Speed: 16MHz
• Connectivity: SmartCard, UART/USART
• Peripherals: LED, POR, WDT
• Number Of I /o: 14
• Program Memory Size: 16KB (16K x 8)
• Program Memory Type: Flash RAM
• Eeprom Size: 16K x 8
• Ram Size: 256 x 8
• Voltage - Supply (vcc/vdd): 2.85 V ~ 5.4 V
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 24-SSOP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Data Converters: -
• Other names: Q1468934; T89C5121-ICSIL; T89C5121-ICSIL

DC/DC Clock
Clock Control Register
Clock Prescaler
4164G–SCR–07/06
The DC/DC block needs a clock with a 50% duty cycle. The frequency must also respect
a value between 3.68 MHz and 4 MHz. The first requirement imposes a divider in the
clock path and the second constraint is solved with the use of a prescaler.
Figure 13. Functional Block Diagram
This register is used to reload the clock prescaler of the DC/DC converter clock.
Table 11. DCCKPS Register
DCCKPS - DC/DC converter Reload Register (BFh)
Reset Value = XXXX XX11b
Before supplying the DC/DC block, the oscillator clock is divided by a factor 2 to 5 to
adapt the clock needed by the DC/DC converter. This factor is controlled with the
DCCKPS register.
The prescaler factor must be chosen to match the requirement range which is 4MHz.
Table 12. Examples of Factors
Number
Bit
7:2
1:0
XTAL (MHz)
7
-
14.756
12
16
20
8
Mnemonic
DCCKPS
Bit
-
6
-
F
OSC
Description
Reserved
Do not use write those bits
Clock Reload Register
Prescaler value
00b: Division factor equals 2
01b: division factor equals 3
10b: division factor equals 4
11b: division factor equals 5 (reset value which minimize the consumption)
DCCKPS Value
5
-
00h
01h
02h
02h
03h
(2 to 5)
DCCKPS
Address BFh
1
4
-
Prescaler
Factor
2
3
4
4
5
3
-
F
2 to 5
OSC
2
-
DC/DC Converter CLK (MHz)
A/T8xC5121
F
CLK_DC/DC
DCCKPS
1
3.689
4
4
4
4
DCCKPS
0
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