Datasheet BA6893AK Datasheet (ROHM)

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.

Applications
Portable CD players

Features

1) Four H-bridge driver circuits.

2) DC to DC converter control circuit.

3) Reset circuit.

4) Shock detection circuit.

5) Battery recharge circuit.

6) Ripple filter circuit.

7) Audio reference output.

8) Low power consumption.

9) Thermal shutdown circuit.

10) QFP44 package.

Absolute maximum ratings (Ta = 25C)

Recommended operating conditions (Ta = 25C)

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Optical disc ICs BA6893AK

Block diagram

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Optical disc ICs BA6893AK

Pin descriptions

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Optical disc ICs BA6893AK

Input / output circuits

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Optical disc ICs BA6893AK

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Electrical characteristics (unles s o t h erwise noted, Ta = 25C, BATT = 2.4V, VSYS1 = VSYS2 = 3.2V, VREF = 1.6V,

CHGV

CC = 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.

(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 AV

CC (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
R2R4

(V)

VSYS1 = 1.20

R1 S R3
R1R3

R2 S R4
R2R4

(4) Audio reference circuit block
One half of the AV

CC voltage (pin 14) generated by the rip-

ple filter circuit is output from AREF (pin 10). The output
impedance is 4.0kΩ (Typ.).
(5) Charging circuit block
The power supply for the charging circuit block is

CC (pin 41), and is independent from the other cir-

CHGV
cuits. The resistance between RCHG (pin 33) and GND
sets the charging current. This current is drawn from
SEL.

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(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.

t = CSPRT

VTH

(sec)

ISPRT

(VTH = 1.20V, ISPRT = 10µA)

(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 = 65kΩ)

Optical disc ICs BA6893AK

(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.

V

t = CSPRT

TH

(sec)

IOFF

(VTH = 1.20V, IOFF = 20µA)

(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.

t = CSPRT

V

TH

(sec)

IHV

(VTH = 1.20V, IHV = 20µA)

(7) H-bridge driver block

(1) Gain setting

The driver input resistance is 11k Ω (Typ.) for channels 1,
3, and 4, and 7.5kΩ for channel 2. Set the gain according
to the following formula.

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 0.1µF).

(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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Optical disc ICs BA6893AK

Application example

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External dimensions (Units: mm)

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