IDT1339 Integrated Device Technology, IDT1339 Datasheet - Page 10

• Manufacturer Part Number: IDT1339
• Description: Real-time Clock With Serial I 2c Interface
• Manufacturer: Integrated Device Technology

Trickle Charger Register (10h)
The simplified “Programmable Trickle Charger” schematic shows the basic components of the trickle charger. The
trickle-charge select (TCS) bits (bits 4 to 7) control the selection of the trickle charger. To prevent accidental enabling, only
a pattern on 1010 enables the trickle charger. All other patterns disable the trickle charger. The trickle charger is disabled
when power is first applied. The diode-select (DS) bits (bits 2 and 3) select whether or not a diode is connected between
V
6 shows the bit values.
Table 6. Trickle Charger Register (10h)
Warning: The ROUT value of 250 must not be selected whenever
The user determines diode and resistor selection according to the maximum current desired for battery or super cap
charging. The maximum charging current can be calculated as illustrated in the following example. Assume that a 3.3 V
system power supply is applied to
been enabled with a diode and resistor R2 between
calculated as follows:
As the super cap or battery charges, the voltage drop between
current decreases.
IDT™ REAL-TIME CLOCK WITH SERIAL I
TCS3 TCS2 TCS1
CC
Bit 7
IDT1339
REAL-TIME CLOCK WITH SERIAL I
X
X
X
1
1
1
1
1
1
0
and V
I
MAX
Bit 6
BACKUP
X
X
X
0
0
0
0
0
0
0
= (3.3 V - diode drop) / R2
Bit 5
. The ROUT bits (bits 0 and 1) select the value of the resistor connected between
X
X
X
1
1
1
1
1
1
0
TCS0
Bit 4
X
X
X
0
0
0
0
0
0
0
Bit 3
2
DS1
C INTERFACE
V
0
1
X
0
1
0
1
0
1
0
2
CC
C INTERFACE
and a super cap is connected to V
Bit 2
DS0
(3.3 V - 0.7 V) / 2k
0
1
X
1
0
1
0
1
0
0
ROUT 1 ROUT 0
Bit 1
V
X
X
0
0
0
1
1
1
1
0
CC
and V
Bit 0
10
BACKUP
X
X
0
1
1
0
0
1
1
0
V
CC
1.3 mA
and V
. The maximum current I
Disabled
Disabled
Disabled
No diode, 250 resistor
One diode, 250 resistor
No diode, 2k resistor
One diode, 2k resistor
No diode, 4k resistor
One diode, 4k resistor
Initial power-up values
V
CC
BACKUP
BACKUP
is greater than 3.63 V.
Function
. Also assume that the trickle charger has
decreases and therefore the charge
MAX
IDT1339
V
would therefore be
CC
and V
BACKUP
REV H 112008
. Table
RTC