MAX1647 Datasheet, PDF (17/24 Pages) Maxim Integrated Products – Chemistry-Independent Battery Chargers

Chemistry-Independent
Battery Chargers
Each communication with the MAX1647 begins with a
start condition that is defined as a falling edge on SDA
with SCL high. The device address follows the start
condition. The MAX1647 device address is 0b0001001
(0b indicates a binary number), which may also be
denoted as 0x12 (0x indicates a hexadecimal number)
for Write-Word commands, or 0x13 in hexadecimal for
Read-Word commands (note that the address is only
seven bits, and the hexadecimal representation uses
R/W as 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 protocol
should be 0b00010010. Table 2 describes the functions
of the 16 different data bits (D0–D15). Bit 0 refers to the
D0 bit in the Write-Word protocol (Figure 7).
Whenever the BATTERY_PRESENT status bit is clear,
the HOT_STOP bit is set, regardless of any previous
ChargerMode( ) command. To charge a battery that
has a thermistor impedance in the HOT range (i.e.,
THERMISTOR_HOT = 1 and THERMISTOR_UR = 0),
the host must use the ChargerMode( ) command to
clear HOT_STOP after the battery is inserted. The
HOT_STOP bit returns to its default power-up condition
(‘1’) whenever the battery is removed.
ChargingVoltage( )
The ChargingVoltage( ) command uses Write-Word
protocol. The command code for ChargingVoltage( ) is
0x15; thus, the CMD7–CMD0 bits in Write-Word proto-
col should be 0b00010101. The 16-bit binary number
formed by D15–D0 represents the voltage set point
(V0) in millivolts; however, since the MAX1647 has only
16mV resolution in setting V0, the D0, D1, D2, and D3
bits are ignored. For D15 = D14 = 0:
( ) VOLTAGE_OR = 0 and V0 in Volts = 4 x REF x VDAC
2¹⁰
In equation 1, VDAC is the decimal equivalent of the
binary number represented by bits D13, D12, D11,
D10, D9, D8, D7, D6, D5, and D4 programmed with the
ChargingVoltage( ) command. For example, if D4–D13
are all set, VDAC is the decimal equivalent of
0b1111111111 (1023). If either D15 or D14, or both
D15 and D14, are set, all the bits in the voltage DAC
(Figure 6a) are set, regardless of D13–D0, and the
status register’s VOLTAGE_OR bit is set. For D15 = 1
and/or D14 = 1:
( ) VOLTAGE_OR = 1 and V0 in Volts = 4 x REF x 210 - 1
2¹⁰
Table 2. ChargerMode( ) Bit Functions
BIT NAME
BIT
POR
POSITION* VALUE**
FUNCTION
INHIBIT_CHARGE
0
0
0 = Allow normal operation; clear the CHG_INHIBITED status bit.
1 = Turn the charger off; set the CHG_INHIBITED status bit.
ENABLE_POLLING
POR_RESET
RESET_TO_ZERO
1
—
Not implemented. Write 0 into this bit.
0 = No change in any non-ChargerMode( ) settings.
2
—
1 = Change the voltage and current settings to 0xFFFF and 0x00C0
respectively; clear the THERMISTOR_HOT and ALARM_INHIBITED bits.
3
—
Not implemented. Write 0 into this bit.
N/A
4, 7, 8, 9,
11–15
—
Not implemented. Write 1 into this bit.
BATTERY_PRESENT_MASK
5
0
0 = Interrupt on either edge of the BATTERY_PRESENT status bit.
1 = Do not interrupt because of a BATTERY_PRESENT bit change.
POWER_FAIL_MASK
6
1
0 = Interrupt on either edge of the POWER_FAIL status bit.
1 = Do not interrupt because of a POWER_FAIL bit change.
HOT_STOP
10
1
0 = The THERMISTOR_HOT status bit does not turn the charger off.
1 = THERMISTOR_HOT turns the charger off.
*Bit position in the D15–D0 data.
N/A = Not available.
**Power-on reset value.
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