BQ24152 Datasheet, PDF (21/38 Pages) Texas Instruments – Fully Integrated Switch-Mode One-Cell Li-Ion Charger with Full USB Compliance and USB-OTG Support

bq24152
www.ti.com ...................................................................................................................................................................................................... SLUS847 – JUNE 2008
High Impedance Mode
When control bit of HZ-MODE is set to "1" and the OTG pin is not in active status, the bq24152 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 bq24152 operates in 32 minute mode and the crude 32 second
timer is disabled. In 32 minute mode, when VBUS is below UVLO, the bq24152 operates in high impedance
mode regardless of the setting of the HZ_MODE bit.
Output Inductor and Capacitance Selection Guidelines
The bq24152 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 bq24152 operates as a DC/DC converter, with the
termination disabled. The robust internal compensation design ensures the stable operation when the
host-controlled switch is turned off. With the input overvoltage protection, output current regulation and high
efficiency power conversion, the bq24152 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.
MODE
IN Condition
OUT Condition
I²C
Buck
I_(SHORT)
Boost
Q1
Note
Table 3. State Machine Table 1 of bq24152
POWER DOWN
VBUS < UVLO
V_(AUXPWR) < V_(SHORT)
VBUS > UVLO
V_(AUXPWR) > V_(SHORT)
Off
Off
Off
Off
Off
POR when out
CHARGE CONFIGURE
OPA_MODE = 0
HZ_MODE = 0
OTG Inactive
VBUS > UVLO
VBUS < VBUS(MIN)
or
VBUS < V_{(SLP_ENT)}
or
CE = HIGH
OPA_MODE = 1
or HZ_MODE = 1
or
VBUS > VBUS(MIN)
VBUS > V_{(SLP_ENT)}
+ V_{(SLP_EXIT)}
or VBUS > UVLO
OTG Active
On
Off
Off
Off
On/Off
SHORT CIRCUIT
OPA_MODE = 0
HZ_MODE = 0
OTGIinactive
VBUS < VBUS(MIN)
VBUS < V_{(SLP_ENT)}
+V_{(SLP_EXIT)}
V_(AUXPWR) < V_(SHORT)
CE = Low
No Faults
OPA_MODE = 1
or HZ_MODE = 1
VBUS < VBUS(MIN)
VBUS < V_{(SLP_ENT)}
or
V_(AUXPWR) < V_(SHORT)
CE = HIGH
or Faults
or OTG Active
On
Off
On
Off
On
PWM CHARGE
OPA_MODE = 0
HZ_MODE = 0
OTG Inactive
VBUS < VBUS(MIN)
VBUS < V_{(SLP_ENT)}
+V_{(SLP_EXIT)}
V_(AUXPWR) < V_(SHORT)
CE = Low
No Faults
OPA_MODE = 1
or HZ_MODE = 1
VBUS < VBUS(MIN)
VBUS < V_{(SLP_ENT)}
or
V_(AUXPWR) < V_(SHORT)
CE = HIGH
or Faults
or OTG Active
On
On
Off
Off
On
Copyright © 2008, Texas Instruments Incorporated
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