Ds1302 streaming Charging

Source: http://hi.baidu.com/piane/homechoose a two pole and a resistance (2 k) charging current about 2mA
Select a diode and a resistor (4 K) for charge current of approximately 1mA
Selecting a diode and a resistor (8 K) charging current of about 3.6 mads1302 is a dropstream charging, so the charging current is small, a 80mA V/2mA rechargeable battery is used full for about 36 hours

Streaming charging Controller

2-3 bits: DS = 01 is a Diode
DS = 10 is two Diodes
DS = 00 no diode, cannot charge
DS = 11 No diode, cannot charge

0-1 bits: rs = 00 no resistor, cannot charge
Rs = 01 2 K
Rs = 10 4 K
Rs = 11 8 K

4-7 bits: TCS = 1010 can be charged. Other combinations cannot be charged.

10100101 one diode resistor 2 K
10100110 one diode resistor 4 K
10100111 one diode resistor 8 K
10101001 two diode resistors 2 K
10101010 two diode resistors 4 K
10101011 two diode resistors 8 K
01011100 initialize power supply

Figure 1A typical flat charger circuit is provided, which specifies that the four-bit high of the flat charger register is used to enable the flat charger, and the four-bit low is used to select the diode pressure difference and throttling resistance. You can insert a diode in the charging path, or choose not to use a diode. The available resistance values are 250 Ω, 2 kb, or 4 kb. Some devices provide different diode and resistor configurations.

The capacitor is connected between the vbackup and the ground (Figure 2). The user selects the diode and resistor based on the maximum charging current required.

Calculate charging current

The maximum charging current can be calculated as follows: assuming that the system power of 3.3v is added to VCC, the dropper charger is enabled, no diode is used, and a 2 k Ω resistor is selected. When the capacitor voltage is zero, the maximum charge current can be calculated:

IMAX = (VCC-diode pressure difference)/R2

= (3.3 V-0 V)/R2

≈ (3.3 V-0 V)/2 k Ω

≈. 1. 65mA

As the vbackup voltage increases, the charging current gradually decreases.

.......................

**************************************** ******************

 

DS 1302 streaming Control Section:

1 0 0 1 0 0 1 tcs ds Rs

Register location 0x90; register location name

TCS bits (4-7) 1010 enable the streaming charging function and disable other settings.

The ds bits (2-3) 01 has a diode In The Middle Of vcc2.

10 There are two diodes In The Middle Of vcc2.

Settings,

The resistance between Rs bits (0-1) and vcc2

RS bits	Register	Typical Value
00	None	None
01	R1	2 K ou
10	R2	4 K ou
11	R3	8 K ou

** The two diodes are connected in series ..

** TCS: streaming charging options

DS: Number of Diodes

RS: select a bit for the resistance of the throttling resistor.