ROHM BA9755S Datasheet

1

Multimedia ICs

High voltage controller for CRT
displays

BA9755S

The BA9755S is an LSI chip with a chopper voltage controller designed to control the anode voltage of multiscan
monitors and other CRTs. There are two internal high-precision power supplies, each with an output voltage preci­sion of ±1%. Using a high-precision voltage detection resistor makes it possible to set anode voltage without adjust­ment. Other internal components include an output voltage error detector and an overcurrent detector, which detects
overcurrent when the power is turned on.

•

Applications

CRT displays and HDTV products

•

Features

1) Internal chopper voltage controller.

2) Two internal high-precision power supplies, each
with an output voltage precision of ±1%.

3) Internal output voltage error detector.

4) Internal buffer circuit that directly drives power MOS­FET for output drive.

•

Absolute maximum ratings (Ta = 25°C)

•

Recommended operating voltage (Ta = 25°C)

Parameter Symbol Limits Unit

Applied voltage 1

V

CC118

∗

1

V

Applied voltage 2

V

CC220

∗

2

V

Power dissipation

Pd 600

∗

1

mW

Operating temperature

Topr – 25 ~ + 75 °C

Storage temperature

Tstg – 55 ~ + 125 °C

∗

3 Reduced by 6.0mW for each increase in Ta of 1°C over 25°C.

∗

1 18pin ∗ 2 3pin

Parameter Symbol Limits Unit

Applied voltage 1 V

CC111 ~ 13 V

Applied voltage 2 V

CC211 ~ 16 V

∗

Used with condition

V

CC2 ⭌ VCC1

2

Multimedia ICs BA9755S

•

Block diagram

1

2

3

4

5

6

7

8

9

18

17

16

15

14

13

12

11

10

PROTOUT

VREG9

VREG6

XREF

XRAYIN

ABLIN

PONDET

ERROUT

GND

PWMOUT

HDIN

MMCR

SAWOUT

AGC

ERRIN

ERRREF

+

–

SAW
GEN.

AGC
TYPE

+

–

REF

9.0V

REF

6.0V

+

–

LATCH

+

–

GND

Buffer

START

M. M.

PV

CC

Power VCC

VCC

Sig VCC

3

Multimedia ICs BA9755S

Pin No.

Pin name

1

GND

Ground
This is the common ground for the small signal system and the power system, and so requires
a stable ground suitable for common impedance.

2

PWMOUT

PWM wave output
Output is fixed at the low level when the protector circuit or thermal shutdown circuit is activated.

3

PV

CC

Power supply for the power system. Place a decoupling capacitor in proximity to this pin.

4

HDIN

HD pulse input. The input signal should be shorter than the rise time (

µs).

5

MMCR

Shifts the phase of the serrated wave. Use a charge resistance higher than 4.7kΩ.

Internal mono-multi time constant setting.

6

SAWOUT

f

Max. 80kHz→C = 1500p, fMax. 60kHz→C = 2000p

7

AGC

Set capacity according to the linearity of the minimum oscillation frequency and the response
time during frequency change.

AGC time constant setting.

8

ERRIN

Input of the error amplifiers feedback voltage.

9

ERRREF

Input of the error amplifiers feedback voltage.
When this voltage is given a time constant, the IC soft-starts when the power is turned on.

10

ERROUT

Output of the error detection voltage.

11

PON DET

12

ABLIN

Beam protector input. When the protector is activated, the latch locks and PWM output is fixed
at the low level.

13

XRAYIN

X-ray protector input. When the protector is activated, the latch locks and PWM output is fixed
at the low level.

14

XREF

Input of the X-ray protector's reference voltage.

15

VREG6

Reference voltage output (6V). Output variation is guaranteed to be 1% or less (with trimming).
This circuit is completely separate from the 9V system. Output is stopped when the thermal
shutdown circuit is activated. Use a 47

µF bypass capacitor.

16

VREG9

Reference voltage output (9V). Output variation is guaranteed to be 1% or less (with trimming).
This circuit is completely separate from the 6V system. Output is stopped when the thermal
shutdown circuit is activated. Use a 10

µF bypass capacitor.

17

PROTOUT

Protector output.
Output changes to the high level when the protector circuit or thermal shutdown circuit is activated.

18

Power supply for the signal system.
Place a decoupling capacitor in proximity to this pin.

Function

Serrated wave output. Adjust maximum capacity by changing maximum oscillation frequency.

V

CC

Setting the time constant for the protector output suppression time and input of the beam
protectors reference voltage. This stops the protectors until the system stabilizes. The latch
can be unlocked by raising the voltage of this pin above 4.5V.

f

Max. 120kHz→C = 1000p, fMax. 100kHz→C = 1200p

•

Pin descriptions