DS1305
STATUS REGISTER (READ 10H)
BIT7
BIT6
BIT5
BIT4
BIT3
BIT2
BIT1
BIT0
IRQF0
0
0
0
0
0
0
IRQF1
IRQF0 (Interrupt 0 Request Flag) – 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) – 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 4–7)
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 2–3) 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 2.
Figure 3. PROGRAMMABLE TRICKLE CHARGER
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DALLAS [ DALLAS SEMICONDUCTOR ]
