MAX1647 Maxim, MAX1647 Datasheet - Page 19

• Manufacturer Part Number: MAX1647
• Description: Chemistry-Independent Battery Chargers
• Manufacturer: Maxim

Two sources of current in the MAX1647 charge the bat-
tery: a binary-weighted linear current source sources
from IOUT, and a switching regulator controls the current
flowing through the current-sense resistor (R1). IOUT
provides a small maintenance charge current to com-
pensate for battery self-discharge, while the switching
regulator provides large currents for fast charging.
IOUT sources from 1mA to 31mA. Table 3 shows the
relationship between the value programmed with the
Table 3. Relationship Between IOUT Source Current and ChargingCurrent( ) Value
Note 1: Logical AND of THERMISTOR_HOT, HOT_STOP, NOT(THERMISTOR_UR).
Figure 9. Average Voltage Between CS and BATT vs. Current DAC Code
INHIBITED
CHARGE_
0
0
0
0
0
0
0
0
0
0
1
(NOTE 1)
0
0
0
0
0
0
0
0
x
1
x
______________________________________________________________________________________
INHIBITED
ALARM_
0
0
0
0
0
0
0
0
1
x
x
ChargingVoltage( )
0x0010–0xFFFF
0x0010–0xFFFF
0x0010–0xFFFF
0x0010–0xFFFF
0x0010–0xFFFF
0x0010–0xFFFF
0x0000–0x000F
2.94
185
94
0b000001
SEL = OPEN OR SEL = VL
x
x
x
x
CURRENT DAC CODE, DA5–DA0 BITS
0b100000
ChargingCurrent( )
Chemistry-Independent
0x0001–0x001F
0x0001–0x001F
0x0001–0x001F
0x0020–0xFFFF
0x0020–0xFFFF
0x0020–0xFFFF
ChargingCurrent( ) command and IOUT source current.
The CCV_LOW comparator checks to see if the output
voltage is too high by comparing CCV to REF / 4. If
CCV_LOW = 1 (when CCV < REF / 4), IOUT shuts off,
preventing the output voltage from exceeding the voltage
set point specified by the ChargingVoltage( ) register.
VOLTAGE_NOTREG = 1 whenever the internal clamp
pulls down on CCV. (The internal clamp pulls down on
CCV to keep its voltage close to CCI’s voltage.)
0x0000
x
x
x
x
0b111111
Battery Chargers
CCV_LOW
0
1
1
0
1
1
x
x
x
x
x
VOLTAGE_
NOTREG
x
0
1
x
0
1
x
x
x
x
x
1mA–31mA
1mA–31mA
CURRENT
OUTPUT
31mA
31mA
IOUT
0mA
0mA
0mA
0mA
0mA
0mA
0mA
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