The BQ2405x series of devices are highly integrated Li-Ion and Li-Pol linear chargers devices targeted at space-limited portable applications. The devices operate from either a USB port or AC adapter. The high-input voltage range with input overvoltage protection supports low-cost unregulated adapters.
The BQ2405x has a single power output that charges the battery. A system load can be placed in parallel with the battery as long as the average system load does not keep the battery from charging fully during the 10-hour safety timer.
The battery is charged in three phases: conditioning, constant current, and constant voltage. In all charge phases, an internal control loop monitors the IC junction temperature and reduces the charge current if an internal temperature threshold is exceeded.
The charger power stage and charge current sense functions are fully integrated. The charger function has high accuracy current and voltage regulation loops, charge status display, and charge termination. The precharge current and termination current threshold are programmed through an external resistor. The fast charge current value is also programmable through an external resistor.
PART NUMBER | PACKAGE | BODY SIZE (NOM) |
---|---|---|
BQ24050 | WSON (10) | 2.00 mm × 2.00 mm |
BQ24052 |
PIN | I/O | DESCRIPTION | |
---|---|---|---|
NAME | NO. | ||
CHG | 8 | O | Low (FET on) indicates charging and Open Drain (FET off) indicates no Charging or Charge complete. |
D+ | 5 | I | USB port D+ input connection |
D– | 6 | I | USB port D– input connection |
IN | 1 | I | Input power, connected to external DC supply (AC adapter or USB port). Expected range of bypass capacitors 1 μF to 10 μF, connect from IN to VSS. |
ISET | 2 | I | Programs the Fast-charge current setting. External resistor from ISET to VSS defines fast charge current value. Range is 52.3k (10 mA) to 540 Ω (1 A). |
ISET2 | 7 | I | Programming the Input/Output Current Limit for the USB or Adaptor source: High = 500 mA max, Low = ISET, FLOAT = 100 mA max. D+D– Detection initially sets the charge threshold and requires ISET2 to change states to take control. |
OUT | 10 | O | Battery Connection. System Load may be connected. Average load should not be excessive, allowing battery to charge within the 10-hour safety timer window. Expected range of bypass capacitors 1 μF to 10 μF. |
PRE-TERM | 4 | I | Programs the Current Termination Threshold (5 to 50% of Iout which is set by ISET) and Sets the Precharge Current to twice the Termination Current Level. |
Expected range of programming resistor is 1k to 10 kΩ (2k: IOUT/10 for term; IOUT/5 for precharge) | |||
TS | 9 (1) | I | Temperature sense pin connected to ‘50 — 10k at 25°C NTC thermistor, ’52 — 100k NTC at 25°C, in the battery pack. Floating TS Pin or pulling High puts part in TTDM and disable TS monitoring, Timers and Termination. Pulling pin Low disables the IC (CE function). If NTC sensing is not needed, connect this pin to VSS through an external ‘50 — 10-kΩ /’52—100-kΩ resistor. A ‘50 — 250-kΩ/’52 880-kΩ from TS to ground will prevent IC entering TTDM when battery with thermistor is removed. |
VSS | 3 | – | Ground terminal |
Thermal Pad | Pad 2x2mm2 | – | There is an internal electrical connection between the exposed thermal pad and the VSS pin of the device. The thermal pad must be connected to the same potential as the VSS pin on the printed circuit board. Do not use the thermal pad as the primary ground input for the device. VSS pin must be connected to ground at all times. |