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Optical disc ICs
4-channel driver and power controller
BA6893AK
The BA6893AK is a 4-channel driver and power supply that includes the reset, recharge, and shock detection circuits required for portable CD players on a single IC. The driver block power supply uses the on-chip switching regulator, making this component an ideal choice for low-power sets. FApplications Portable CD players FFeatures 1) Four H-bridge driver circuits. 2) DC to DC converter control circuit. 3) Reset circuit. 4) Shock detection circuit. 5) Battery recharge circuit. FAbsolute maximum ratings (Ta = 25_C)
6) 7) 8) 9) 10)
Ripple filter circuit. Audio reference output. Low power consumption. Thermal shutdown circuit. QFP44 package.
FRecommended operating conditions (Ta = 25_C)
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FBlock diagram
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FPin descriptions
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FInput / output circuits
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FElectrical characteristics (unless otherwise noted, Ta = 25_C, BATT = 2.4V, VSYS1 = VSYS2 = 3.2V, VREF = 1.6V, CHGVCC = 0V, and fCLK = 88.2kHz)
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FCircuit operation (1) Empty detector block When the voltage applied to the BSEN pin falls below the detector voltage, EMP (pin 35) goes from high level to low level (open-collector output). The detector voltage has 50mV (Typ.) of hysteresis to prevent output chattering. Use SEL (pin 42) to switch the detection voltage as shown below.
BA6893AK
(2) Reset circuit block At about 90% (Typ.) of the DC / DC comparator output voltage, RESET (pin 3) goes from low level to high level, and AMUTE (pin 34) goes from high level to low level. The reset voltage has 50mV (Typ.) of hysteresis to prevent output chattering. (3) Ripple filter circuit By connecting an external PNP transistor, a voltage of (VSYS1 0.24)V is supplied from AVCC (pin 14). Connect a ripple bypass capacitor between CRIP (pin 11) and GND.
A thermal shutdown circuit is provided, and when the chip temperature reaches 150_C (Typ.) the charging current is cut. The chip starts operating again at about 120_C (Typ.). (6) DC / DC converter block (1) Output voltage A 3.2V (Typ.) voltage multiplier circuit can be constructed using external components. This voltage can be varied with the addition of an external resistor. The setting method is as follows. R2 S R4 R1 S R3 ) R1)R3 R2)R4 VSYS1 = 1.20 (V) R2 S R4 R2)R4
(2) Short protect function When the error amplifier output (pin 6) has switched to the high-level state, SPRT (pin 8) is charged, and when the voltage reaches 1.2V (Typ.), the SW (pin 5) switching stops. The time until switching stops is set by the capacitor connected to SPRT (pin 8) according to the following formula. (4) Audio reference circuit block One half of the AVCC voltage (pin 14) generated by the ripple filter circuit is output from AREF (pin 10). The output impedance is 4.0k (Typ.). (5) Charging circuit block The power supply for the charging circuit block is CHGVCC (pin 41), and is independent from the other circuits. The resistance between RCHG (pin 33) and GND sets the charging current. This current is drawn from SEL. VTH t = CSPRT (sec) ISPRT (VTH = 1.20V, ISPRT = 10A)
(3) Soft start function The soft start function operates when a capacitor is connected between DEAD (pin 4) and GND. Also, the maximum duty can be varied by connecting a resistor to pin 4. t = CDEAD R (sec) (R = 65k)
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(4) Power off function When low-level is applied to OFF (pin 40), SPRT (pin 8) is charged, and when the voltage reaches 1.2V (Typ.), the SW (pin 5) switching stops. The time until switching stops is set by the capacitor connected to SPRT (pin 8) according to the following formula. VTH t = CSPRT (sec) IOFF (VTH = 1.20V, IOFF = 20A) (5) Over voltage protection circuit When the voltage applied to BSEN (pin 1) reaches 8.4V (Typ.), SPRT (pin 8) is charged, and when the voltage reaches 1.2V (Typ.), the SW (pin 5) switching stops. The time until switching stops is set by the capacitor connected to SPRT (pin 8) according to the following formula. VTH t = CSPRT (sec) IHV (VTH = 1.20V, IHV = 20A) (7) H-bridge driver block (1) Gain setting The driver input resistance is 11k (Typ.) for channels 1, 3, and 4, and 7.5k for channel 2. Set the gain according to the following formula.
BA6893AK
The driver output stage power supply is HVCC (pin 36), and the bridge circuit power supply is VSYS2 (pin 15). Connect a bypass capacitor between these two power supplies (approximately 0.1F). (2) Mute function Of the four drivers, channel 1 has a brake function, and the other channels have a mute function. When BRAKE1 (pin 23) is set to high level, both channel 1 outputs go low level, and the circuit enters brake mode. When MUTE2 (pin 21) is set to high level, the channel 2 output is muted. When MUTE34 (pin 19) is set to high level, the channel 3 and 4 outputs are muted. (3) VREF drop mute When the voltage applied to VREF (pin 16) is 1.0V or less (Typ.), the driver outputs are set to high impedance. (4) Thermal shutdown When the chip temperature reaches 150_C (Typ.) the output current is cut. The chip starts operating again at about 120_C (Typ.). (8) PWM power supply drive block This detects the maximum output level from among the four channels, and supplies the load drive power supply for the PWM. The external components are a PNP transistor, coil, Schottky diode, and capacitor.
R: Externally-connected input resistor
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FApplication example
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FExternal dimensions (Units: mm)
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