DS1305 Datasheet, PDF(8/22 Page) Dallas Semiconductor

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DS1305 Datasheet, PDF (8/22 Pages) Dallas Semiconductor – Serial Alarm Real Time Clock RTC

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DS1305

AIE1 (Alarm Interrupt Enable 1) â When set to a logic 1, this bit permits the interrupt 1 request flag

(IRQF1) bit in the status register to assert INT1 (when INTCN = 1) or to assert INT0 (when INTCN = 0).

When the AIE1 bit is set to logic 0, the IRQF1 bit does not initiate an interrupt signal.

STATUS REGISTER (READ 10h)

BIT7

BIT6

BIT5

BIT4

BIT3

BIT2

BIT1

IRQF1

BIT0

IRQF0

IRQF0 (Interrupt 0 Request Flag) â A logic 1 in the interrupt request flag bit indicates that the current

time has matched the Alarm 0 registers. If the AIE0 bit is also a logic 1, the INT0 pin goes low. IRQF0 is

cleared when the address pointer goes to any of the Alarm 0 registers during a read or write.

IRQF1 (Interrupt 1 Request Flag) â A logic 1 in the interrupt request flag bit indicates that the current

time has matched the Alarm 1 registers. This flag can be used to generate an interrupt on either INT0 or

INT1 depending on the status of the INTCN bit in the control register. If the INTCN bit is set to a logic 1

and IRQF1 is at a logic 1 (and AIE1 bit is also a logic 1), the INT1 pin goes low. If the INTCN bit is set

to a logic 0 and IRQF1 is at a logic 1 (and AIE1 bit is also a logic 1), the INT0 pin goes low. IRQF1 is

cleared when the address pointer goes to any of the Alarm 1 registers during a read or write.

TRICKLE CHARGE REGISTER (READ 11H, WRITE 91H)

This register controls the trickle charge characteristics of the DS1305. The simplified schematic of Figure

3 shows the basic components of the trickle charger. The trickle-charge select (TCS) bits (bits 4â7)

control the selection of the trickle charger. To prevent accidental enabling, only a pattern of 1010 enables

the trickle charger. All other patterns disable the trickle charger. On the initial application of power, the

DS1305 powers up with the trickle charger disabled. The diode select (DS) bits (bits 2â3) select whether

one diode or two diodes are connected between VCC1 and VCC2. The resistor select (RS) bits select the

resistor that is connected between VCC1 and VCC2. The resistor and diodes are selected by the RS and DS

bits, as shown in Table 3.

Figure 3. PROGRAMMABLE TRICKLE CHARGER

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