13892 datasheet(94/156 Pages) FREESCALE

94 / 156 page

Analog Integrated Circuit Device Data

Freescale Semiconductor

13892

FUNCTIONAL DEVICE OPERATION

BATTERY INTERFACE AND CONTROL

Crossing the thresholds BATTCYCL and CHGCURR will generate the interrupts CCCVI and CHGCURRI respectively. These

interrupts can be used as a simple way to implement a 3-bar battery meter.

BATTERY THERMISTOR CHECK CIRCUITRY

A battery pack may be equipped with a thermistor, which value decreases over temperature (NTC). The relationship between

temperature T (in Kelvin) and the thermistor value (RT) is well characterized and can be described as RT = R0*e^(B*(1/T-1/T0),

with T0 being room temperature, R0 the thermistor value at T0 and B being the so called B-factor which indicates the slope of

the thermistor over temperature. In order to read out the thermistor value, it is biased from GPO1 through a pull-up resistor RPU.

See also the ADC chapter. The battery thermistor check circuit compares the fraction of GPO1 at ADIN5 with two preset

thresholds, which correspond to 0 and 45 °C, see Table 73. Charging is generally allowed when the thermistor is within the range,

see next section for details.

Table 73. Battery Thermistor Check Main Characteristics

Tlow

24/32 * GPO1

10 k

30 k

-3.0

+2.0

Thigh

10/32 * GPO1

10 k

45 k

+49

+46

+44

CHARGE LED INDICATOR

Since normal LED control via the SPI bus is not always possible in the charging mode, an 8.0 mA max current sink is provided

at the CHRGLED pin for an LED connected to CHRGRAW.

The LED will be activated when standalone charging is started, and will remain under control of the state machine also when

the application is powered on. At the end of charge, the LED is automatically disabled. Through the CHRGLEDEN bit, the LED

can be forced on. In software controlled charging, the LED is under full control of this CHRGLEDEN bit.

Table 74. Charge LED Drivers Main Characteristics

Trickle LED current

CHRGLED = 2.5 V

8.0

CHRGLED = 0.7 V

5.0

Notes

69.

Above conditions represent respectively a USB and a collapsed charger case

Table 75. Charge LED Driver Control

CHRGLEDEN

CHRGLED

0 (default)

Auto

Charger Valid

CHRGRAW

3.8

CHGCURR Threshold

CHRGISNS-BPSNS, current from charger

Debounce Period

BATTMIN, BATTON rising edge (normal

BATTMIN, BATTON rising edge (slow)

1.0

BATTMIN falling edge (slow)

1.0

BATTMIN falling edge (fast)

1.0

BATTCYCL dual edge

100

CHGCURR

1.0

Charger Detect dual edge

100

Temperature Threshold

Voltage at ADIN5

Corresponding Resistor Values

Corresponding Temperature (in °C) *

Rpu

B=3200

B=3500

B=3900

Parameter

Condition

Min

Typ

Max

Units

Table 72. Charger Detectors main characteristics

Parameter

Condition

Min

Typ

Max

Units

13892 датащи(PDF) 94 Page - Freescale Semiconductor, Inc

13892 датащи(HTML) 94 Page - Freescale Semiconductor, Inc

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

датащи скачать

ссылки URL