BQ24188_15 Datasheet, PDF (22/52 Pages) Texas Instruments – bq24188 2A, 30V, Host-Controlled Single-Input, Single Cell Switchmode Li-Ion Battery Charger with Power Path Management and USB-OTG Support

bq24188
SLUSC44A – DECEMBER 2014 – REVISED MAY 2015
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Device Functional Modes (continued)
9.4.14 LDO Output (DRV)
The bq24188 contains a linear regulator (DRV) that is used to supply the internal MOSFET drivers and other
circuitry. Additionally, DRV supplies up to 10mA external loads to power the STAT LED or the USB transceiver
circuitry. The maximum value of the DRV output is 5.3V so it ideal to protect voltage sensitive USB circuits. The
LDO is on whenever a supply is connected to the input of the bq24188 . The DRV is disabled under the following
conditions:
1. V_SUPPLY < UVLO
2. V_SUPPLY < V_BAT + V_SLP
3. Thermal Shutdown
9.4.15 External NTC Monitoring (TS)
The I²C interface allows the user to easily implement the JEITA standard for systems where the battery pack
thermistor is monitored by the host. Additionally, the bq24188 provides a flexible, voltage based TS input for
monitoring the battery pack NTC thermistor. The voltage at TS is monitored to determine that the battery is at a
safe temperature during charging. The JEITA specification is shown in Figure 13.
1.0 C
Charging Current 0.5 C
4.25 V
V_BAT 4.15 V
4.1 V
Portion of spec not covered by TS
Implementation on bq24188
T1
(0°C)
Cold
T2
(10°C)
Cool
T3 T4
(45°C) (50°C)
Warm
T5
(60°C)
Hot
Figure 13. Charge Current During TS Conditions
To satisfy the JEITA requirements, four temperature thresholds are monitored; the cold battery threshold (T_NTC <
0°C), the cool battery threshold (0°C < T_NTC < 10°C), the warm battery threshold (45°C < T_NTC < 60°C) and the
hot battery threshold (T_NTC > 60°C). These temperatures correspond to the V_COLD, V_COOL, V_WARM, and V_HOT
thresholds in the EC table. Charging is suspended and timers are suspended when V_TS < V_HOT or V_TS > V_COLD.
When V_COOL < V_TS < V_COLD, the charging current is reduced to half of the programmed charge current. When
V_HOT < V_TS < V_WARM, the battery regulation voltage is reduced by 140mV from the programmed regulation
threshold. The TS function is disabled by connecting TS directly to DRV (V_TS > V_TSOFF).
The TS function is voltage based for maximum flexibility. Connect a resistor divider from DRV to GND with TS
connected to the center tap to set the threshold. The connections are shown in Figure 14. The resistor values are
calculated using the following equations:
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