LP3913 Datasheet, PDF (41/70 Pages) Texas Instruments – Power Management IC for Flash Memory-Based Portable Media Players

LP3913
www.ti.com
SNVS489I – NOVEMBER 2006 – REVISED SEPTEMBER 2013
charger.
2. USB power is present and supplies the system and the battery.
3. USB power is present but the system demand exceeds the USB current limit, so that the battery provides the
additional power to operate the system.
4. The battery is the sole supply source to the system when no external power source is present
The current flows in the different modes are realized through internal FETS and an external Schottky as
illustrated as follows:
ADAPTER
VDD
USBPW_xxxxR _{xxxxxxxxxxxxxxxxQQ12}
VBATT
Li - Ion Cell
The current provided by the external adapter power or USB power, when inserted, first supplies the system load;
the remainder is used for charging.
The different paths are configured through two internal power FETs, Q1 and Q2, and an external Schottky diode.
Q1 is a Power FET that is only active during USB charging. Q2 functions either as a linear Power FET during
charging or as a low R_DSON switch when no external power is present and the battery discharges to supply power
to the system.
Power Route
Q1
Regulated adapter supply &
battery charging
OFF
USB supply & battery
charging
ON
No external supply & battery
discharging
OFF
Q2
Regulated
Regulated
ON
The Power Routing function will allocate power to the system through the V_DD pin and to the battery. V_DD1, V_DD2,
V_DD3, V_IN1, V_IN2, V_IN3, and V_IN4 must be connected together externally. V_BATT1, V_BATT2, and V_BATT3 must be
connected together externally.
USB Suspend Mode
The LP3913 USB current consumption can be disabled during suspend mode through a dedicated pin
(USBSUSP). Applying a logic 1 to this pin will disable the USB current path and current is reduced to input
leakage current less than 30 µA on the USBPWR pin.
Setting the USB Current Limit
The USB current that is available from the USB on the VBUS wire is limited by default to 100 mA. More current
(up to 800 mA) can be negotiated through a session request protocol between host and peripheral. The USB
current limit needs to be signaled to the LP3913 by means of the USB_ISEL pin or the I_LIMIT Register as indicated
below.
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