Datasheet

bq24610
bq24617
www.ti.com SLUS892B –DECEMBER 2009–REVISED SEPTEMBER 2013
Power Up
The bq24610/7 uses a SLEEP comparator to determine the source of power on the VCC pin, because VCC can
be supplied either from the battery or the adapter. If the VCC voltage is greater than the SRN voltage, bq24610/7
enables the ACFET and disables BATFET. If all other conditions are met for charging, the bq24610/7 then
attempts to charge the battery (See Enabling and Disabling Charging). If the SRN voltage is greater than VCC,
indicating that the battery is the power source, the bq24610/7 enables the BATFET and enters a low-quiescent-
current (<15 μA) SLEEP mode to minimize current drain from the battery.
If VCC is below the UVLO threshold, the device is disabled, ACFET turns off and BATFET turns on.
Enable and Disable Charging
The following conditions must be valid before charge is enabled:
• CE is HIGH
• The device is not in undervoltage lockout (UVLO) and not in VCCLOWV mode
• The device is not in SLEEP mode
• The VCC voltage is lower than the ac overvoltage threshold (VCC < V
ACOV
)
• 30-ms delay is complete after initial power up
• The REGN LDO and VREF LDO voltages are at the correct levels
• Thermal shut (TSHUT) is not valid
• TS fault is not detected
One of the following conditions will stop on-going charging:
• CE is LOW
• Adapter is removed, causing the device to enter UVLO, VCCLOWV, or SLEEP mode
• Adapter is over voltage
• The REGN or VREF LDO is overloaded;
• TSHUT IC temperature threshold is reached (145°C on rising edge with 15°C hysteresis).
• TS voltage goes out of range, indicating the battery temperature is too hot or too cold.
• TTC safety timer out
System Power Selector
The bq24610/7 automatically switches adapter or battery power to the system load. The battery is connected to
the system by default during power up or during SLEEP mode. The battery is disconnected from the system and
then the adapter is connected to the system 30 ms after exiting SLEEP. An automatic break-before-make logic
prevents shoot-through currents when the selectors switch.
The ACDRV is used to drive a pair of back-to-back p-channel power MOSFETs between the adapter and ACP
with sources connected together and to VCC. The FET connected to the adapter prevents reverse discharge
from the battery to the adapter when turned off. The p-channel FET with the drain connected to the adapter input
provides reverse battery discharge protection when off; and also minimizes system power dissipation with its low
r
DS(on)
, compared to a Schottky diode. The other p-channel FET connected to ACP separates the battery from the
adapter, and provides a limited dI/dt when connecting the adapter to the system by controlling the FET turnon
time. The BATDRV controls a p-channel power MOSFET placed between BAT and the system.
When the adapter is not detected, ACDRV is pulled to VCC to keep ACFET off, disconnecting the adapter from
system. BATDRV stays at ACN-6V to connect the battery to the system.
Approximately 30 ms after the device comes out of SLEEP mode, the system begins to switch from the battery to
the adapter. The break-before-make logic keeps both ACFET and BATFET off for 10 µs before ACFET turns on.
This prevents shoot-through current or any large discharging current from going into the battery. BATDRV is
pulled up to ACN and the ACDRV pin is set to VCC-6V by an internal regulator to turn on p-channel ACFET,
connecting the adapter to the system.
When the adapter is removed, the system waits until VCC drops back to within 200 mV above SRN to switch
from the adapter back to the battery. The break-before-make logic still keeps 10 μs dead time. The ACDRV is
pulled up to VCC and the BATDRV pin is set to ACN-6V by an internal regulator to turn on p-channel BATFET,
connecting the battery to the system.
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Product Folder Links: bq24610 bq24617