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Summit SMB137C Battery Charger
The SMB137C is controlled via an I2C bus. Its 7-bit I2C slave address is
programmed during manufacturing.
Required properties:
- compatible: Must be "summit,smb137c".
- reg: The device's 7-bit I2C address.
Optional properties:
- summit,chg-current-ma Maximum battery charging current in milliamps.
Supported values are: 500, 650, 750, 850, 950,
1100, 1300, and 1500.
- summit,term-current-ma Charging terminaton current in milliamps.
Supported values are: 0, 35, 50, 100, and 150.
A value of 0 means no termination current is
used.
- summit,pre-chg-current-ma Maximum battery pre-charging current in
milliamps. This current limit is applied while
the battery voltage is below the pre-charge /
fast-charge threshold. Supported values are:
50, 100, 150, and 200.
- summit,float-voltage-mv Battery voltage threshold in millivolts at which
point charging switches from constant current to
constant voltage. Supported values are: 3460 up
through 4730 in 10 mV steps.
- summit,thresh-voltage-mv Threshold voltage in millivolts which is used to
switch between pre-charge and fast-charge
current limits. Supported values are: 2400 up
to 3100 in 100 mV steps.
- summit,recharge-thresh-mv Specifies the minimum voltage drop in millivolts
below the float voltage that is required in
order to initiate a new charging cycle.
Supported values are: 75 and 120.
- summit,system-voltage-mv Regulated voltage output on the VOUTL pin in
millivolts. Supported values are 4250 and 4460.
- summit,charging-timeout Maximum duration in minutes that a single charge
cycle may last. Supported values are: 0, 382,
764, and 1527. A value of 0 means that no
charge cycle timeout is used and charging can
continue indefinitely.
- summit,pre-charge-timeout Maximum time in minutes spent in the pre-charge
state in any given charge cycle. Supports
values are: 0, 48, 95, and 191. A value of 0
means that there is no limit to the amount of
time that may be spent in the pre-charge state.
- summit,therm-current-ua Thermistor current in microamps to be used for
battery temperature monitoring. Supported
values are 10, 20, 40, and 100. These values
correspond to 100, 50, 25, and 10 kohm NTC
thermistors respectively.
- summit,temperature-min Specifies the minimum temperature at which
charging is allowed. Supported values are
0 to 7. These values correspond to -20 C to
+15 C in 5 C increments for an NTC thermistor
with beta = 4400.
- summit,temperature-max Specifies the maximum temperature at which
charging is allowed. Supported values are
0 to 7. These values correspond to +30 C to
+65 C in 5 C increments for an NTC thermistor
with beta = 4400.
Note: If an optional property is not specified, then the hardware default value
will be used.
Example:
/ {
i2c@f9925000 {
charger@57 {
compatible = "summit,smb137c";
reg = <0x57>;
summit,chg-current-ma = <1500>;
summit,term-current-ma = <50>;
summit,pre-chg-current-ma = <100>;
summit,float-voltage-mv = <4200>;
summit,thresh-voltage-mv = <3000>;
summit,recharge-thresh-mv = <75>;
summit,system-voltage-mv = <4250>;
summit,charging-timeout = <382>;
summit,pre-charge-timeout = <48>;
summit,therm-current-ua = <10>;
summit,temperature-min = <4>; /* 0 C */
summit,temperature-max = <3>; /* 45 C */
};
};
};