BQ24150A Datasheet, PDF (21/41 Pages) Texas Instruments – Fully Integrated Switch-Mode One-Cell Li-Ion Charger With Full USB Compliance and USB-OTG Support

bq24150A
bq24151A
www.ti.com ..................................................................................................................................................................................................... SLUS931 – APRIL 2009
Output Overload Protection
The bq24150A/1A provides a built-in overload protection to prevent the device and battery from damage when
VBUS is over loaded. Once over load condition is detected, Q1 operates in linear mode to limit the output current
while VPMID keeps in voltage regulation. If the overload condition lasts for more than 30 ms, the overload fault is
detected. When an overload condition is detected, the bq24150A/1A turns off the PWM converter, reset
OPA_MODE bit to 0, sets fault status bits, and sends out fault pulse in STAT pin. The boost will not start until the
host clears the fault register.
Battery Voltage Protection
During boosting, when battery voltage is above the battery overvoltage threshold, V_(BATMX), or below the minimum
battery voltage threshold, V_(BAT)min, the bq24150A/1A turns off the PWM converter, reset OPA_MODE bit to 0,
sets fault status bits, and sends out fault pulse in STAT pin. Once battery voltage goes back to the normal level,
the boost starts after host sets OPA_MODE to "1", or the OTG pin remains in active status.
STAT Pin Boost Mode
During normal boosting process, the STAT pin behaves as a high impedance (open-drain) output. Under fault
conditions, a 128-µs pulse is sent out to notify the host.
High Impedance Mode
When control bit of HZ-MODE is set to "1" and the OTG pin is not in active status, the bq24150A/1A operates in
high impedance mode, with the impedance in VBUS pin higher than 165 kΩ. In high impedance mode, a crude
32-second timer is enabled when the battery voltage is below V_(LOWV) to monitor the host control is available or
not. If the crude 32 second timer expires, the bq24150A/1A operates in 32 minute mode and the crude 32
second timer is disabled. In 32 minute mode, when VBUS is below UVLO, the bq24150A/1A operates in high
impedance mode regardless of the setting of the HZ_MODE bit.
Output Inductor and Capacitance Selection Guidelines
The bq24150A/1A provides internal loop compensation. With this scheme, the best stability occurs when the LC
resonant frequency, ƒ_o, is approximately 40 kHz (20 kHz to 80 kHz). Equation 1 is used to calculate the value of
the output inductor, L_OUT, and output capacitor, C_OUT.
1
f_o =
2p ´ L_OUT ´ C_OUT
(1)
To reduce the output voltage ripple, a ceramic capacitor with the capacitance between 4.7 µF and 47 µF is
recommended for C_OUT, see the application section for components selection.
Pre-Regulator Application
Figure 2 shows a typical pre-regulator application that the bq24150A/1A operates as a DC/DC converter, with the
termination disabled. In this application, the host charge controller controls switch Q to achieve pulse-charging
function, and bq24150A/1A converts the input voltage to the lower output voltage (V_OREG). The robust internal
compensation design ensures the stable operation when the host-controlled switch Q is turned off. With the input
overvoltage protection, output current regulation and high efficiency power conversion, the bq24150A/1A is an
ideal choice for pre-regulator used in pulse charging applications.
State Machine Table and State Diagram
Based on the previously-described operation modes, the definitions of all operation states are shown in Table 3
and Table 4, whereas the relationship among different states is shown in Figure 26.
Copyright © 2009, Texas Instruments Incorporated
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