Datasheet

0
mA
0mA
V
OUT
V
SYS(REG)
V
MINSYS
~3.1V
DPPM loop active
Supplement
Mode
I
BAT
I
IN
I
SYS
800 mA
1800 mA
2000 mA
-200 mA
1A
1500 mA
~850 mA
0mA
bq24160, bq24160A
bq24161, bq24161B
bq24163, bq24168
SLUSAO0E –NOVEMBER 2011–REVISED NOVEMBER 2013 www.ti.com
path management (DPPM) circuitry of the bq2416x monitors the current limits continuously, and if the SYS
voltage falls to the V
MINSYS
voltage, it adjusts charge current to maintain the minimum system voltage and supply
the load on SYS. If the charge current is reduced to zero and the load increases further, the bq2416x enters
battery-supplement mode. During supplement mode, the battery FET is turned on and the battery supplements
the system load.
Figure 23. Example DPPM Response (V
Supply
=5V, V
BAT
= 3.1V, 1.5A Input current limit)
V
BAT(REG)
should never be programmed less than V
BAT
. If the battery is ever 5% above the regulation threshold,
the battery OVP circuit shuts the PWM converter off immediately and the battery FET is turned on to discharge
the battery to safe operating levels. If the battery OVP condition exists for the 1ms deglitch, a battery OVP fault is
reported in the I
2
C status registers. The battery OVP fault is cleared when the battery voltage discharges below
V
RCH
or if the IC enters hi-impedance mode (HZ_MODE=1 or CD=1). Always write bq2416x to high impedance
mode before changing V
BATREG
to clear BOVP condition to ensure proper operation.
Battery Only Connected
When a battery voltage less than V
BATUVLO
is connected with no input source, the battery FET is turned on similar
to supplement mode. In this mode, the current is not regulated; however, there is a short circuit current limit. If
the short circuit limit is reached, the battery FET is turned off for the deglitch time (t
DGL(SC1)
). After the recovery
time (t
REC(SC1)
), the battery FET is turned on to test and see if the short has been removed. If it has not, the FET
turns off and the process repeats until the short is removed. This process is to protect the internal FET from over
current. If an external FET is used for discharge, the body diode prevents the load on SYS from being
disconnected from the battery. If the battery voltage is less than V
BATUVLO
, the battery FET (Q4) remains off and
BAT is high-impedance. This prevents further discharging of deeply-discharged batteries.
Battery Discharge FET (BGATE)
The bq2416x contains a MOSFET driver to drive the gate of an external discharge FET between the battery and
the system output. This external FET provides a low impedance path when supplying the system from the
battery. Connect BGATE to the gate of the external discharge MOSFET. BGATE is on under the following
conditions:
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