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Datasheet MAX1647 - Chemistry-Independent Battery Chargers - Maxim Integrated Products

Chemistry-Independent

Battery Chargers

Each communication with the MAX1647 begins with aChargingVoltage( )

start condition that is defined as a falling edge on SDAThe ChargingVoltage( ) command uses Write-Wordwith SCL high. The device address follows the startprotocol. The command code for ChargingVoltage( ) iscondition. The MAX1647 device address is 0b00010010x15; thus, the CMD7–CMD0 bits in Write-Word proto-(0bindicates a binary number), which may also becol should be 0b00010101. The 16-bit binary numberdenoted as 0x12 (0xindicates a hexadecimal number)formed by D15–D0 represents the voltage set pointfor Write-Word commands, or 0x13 in hexadecimal for(V0) in millivolts; however, since the MAX1647 has onlyRead-Word commands (note that the address is only16mV resolution in setting V0, the D0, D1, D2, and D3seven bits, and the hexadecimal representation usesbits are ignored. For D15 = D14 = 0:

R/Was its least significant bit).

ChargerMode( )

The ChargerMode( ) command uses Write-Word proto-col. The command code for ChargerMode( ) is 0x12;thus the CMD7–CMD0 bits in Write-Word protocolIn equation 1, VDAC is the decimal equivalent of theshould be 0b00010010. Table 2 describes the functionsbinary number represented by bits D13, D12, D11,of the 16 different data bits (D0–D15). Bit 0 refers to theD10, D9, D8, D7, D6, D5, and D4 programmed with theD0 bit in the Write-Word protocol (Figure 7).

ChargingVoltage( ) command. For example, if D4–D13Whenever the BATTERY_PRESENT status bit is clear,are all set, VDAC is the decimal equivalent ofthe HOT_STOP bit is set, regardless of any previous0b1111111111 (1023). If either D15 or D14, or bothChargerMode( ) command. To charge a battery thatD15 and D14, are set, all the bits in the voltage DAChas a thermistor impedance in the HOT range (i.e.,(Figure 6a) are set, regardless of D13–D0, and the THERMISTOR_HOT = 1 and THERMISTOR_UR = 0),status register’s VOLTAGE_OR bit is set. For D15 = 1the host must use the ChargerMode( ) command toand/or D14 = 1:

clear HOT_STOP afterthe battery is inserted. TheHOT_STOP bit returns to its default power-up condition(‘1’) whenever the battery is removed.

Table 2. ChargerMode( ) Bit Functions

*Bit position in the D15–D0 data.**Power-on reset value.

N/A = Not available.

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MAX1647/MAX1648