SANYO VPC-MZ2EX, VPC-MZ2, VAR-GA4U, VAR-GA4EX, VAR-GA4E POWER CIRCUIT DESCRIPTION
1-4. PW1 POWER CIRCUIT DESCRIPTION
1. Outline
This is the main PW1 power circuit, and is comprised of the
following blocks.
Switching controller (IC501)
Digital and LCD system and 5.0 V system power output
(L5005, Q5015, D5005, C5036, C5037)
Digital 3.3 V system power supply (L5002, Q5003, D5002,
C5018)
Digital 3.4 V system power supply (L5003, Q5009, D5004,
C5029)
Series regulator (IC502)
Digital 2.5 V system power supply (Q5007, C5025, C5026)
Analog system 5 V power supply (L5008, Q5020, D5006,
C5045)
2. Switching Controller (IC501)
This is the basic circuit which is necessary for controlling the
power supply for a PWM-type switching regulator, and is provided with four built-in channels, only CH1 (digital 3.3 V), CH3
(5 V system), CH2 (digital 3.4 V) and CH4 (analog system 5
V) are used. Feedback from 3.3 V (D) (CH1), 3.4 V (D) (CH2),
5 V (D) (CH3) and 5.0 V (A) power supply outputs are received, and the PWM duty is varied so that each one is maintained at the correct voltage setting level.
2-1. Short-circuit protection circuit
If output is short-circuited for the length of time determined
by the condenser which is connected to Pin (33) of IC501, all
output is turned off. The control signal (P ON, P(A) ON and
LCD ON) are recontrolled to restore output.
3. Digital 3.3 V Power Output
3.3 V (D) is output. Feedback for the 3.3 V (D) is provided to
the switching controller (Pins (1) of IC501) so that PWM control can be carried out.
4. Digital 3.4 V System Power Output
3.4 V (D) is output. Feedback is provided to the swiching controller (Pin (12) of IC501) so that PWM control can be carried
out.
5. 5 V System Power Output
5 V (D) and 5 V (L) are output. Feedback for the 5 V (D) is
provided to the switching controller (Pin (25) of IC501) so
that PWM control can be carried out.
6. Series Regulator (IC502)
This is provided with one built-in channel. Digital 3.4 V is input, and digital 2.5 V is output.
7. Digital 2.5 V System Power Output
2.5 V (D) is output. Feedback for the 2.5 V (D) is provided to
the Pin (7) of IC502. The current of Q5008 base is controled
so that the voltage of Q5008 collector is 2.5 V.
8. Analog 5 V System Power Output
5 V (A) is output. Feedback is provided to the swiching controller (Pin (36) of IC501) so that PWM control can be carried
out.
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1-5. PW1 STROBE CIRCUIT DESCRIPTION
1. Charging Circuit
When UNREG power is supplied to the charge circuit and the
CHG signal becomes High (3.3 V), the charging circuit starts
operating and the main electorolytic capacitor is charged with
high-voltage direct current.
However, when the CHG signal is Low (0 V), the charging
circuit does not operate.
1-1. Power switch
When the CHG signal switches to Hi, Q5406 turns ON and
the charging circuit starts operating.
1-2. Power supply filter
L5401 and C5401 constitute the power supply filter. They
smooth out ripples in the current which accompany the switching of the oscillation transformer.
1-3. Oscillation circuit
This circuit generates an AC voltage (pulse) in order to increase the UNREG power supply voltage when drops in current occur. This circuit generates a drive pulse with a frequency
of approximately 50-100 kHz. Because self-excited light omission is used, the oscillation frequency changes according to
the drive conditions.
2. Light Emission Circuit
When RDY and TRIG signals are input from the ASIC expansion port, the stroboscope emits light.
2-1. Emission control circuit
When the RDY signal is input to the emission control circuit,
Q5409 switches on and preparation is made to let current
flow to the light emitting element. Moreover, when a STOP
signal is input, the stroboscope stops emitting light.
2-2. Trigger circuit
When a TRIG signal is input to the trigger circuit, D5405
switches on, a high-voltage pulse of several kilovolts is generated inside the trigger circuit, and this pulse is then applied
to the light emitting part.
2-3. Light emitting element
When the high-voltage pulse form the trigger circuit is applied to the light emitting part, currnet flows to the light emitting element and light is emitted.
Beware of electric shocks.
1-4. Oscillation transformer
The low-voltage alternating current which is generated by the
oscillation control circuit is converted to a high-voltage alternating current by the oscillation transformer.
1-5. Rectifier circuit
The high-voltage alternating current which is generated at
the secondary side of T5401 is rectified to produce a highvoltage direct current and is accumulated at electrolytic capacitor C5144 on the CA3 board.
1-6. Voltage monitoring circuit
This circuit is used to maintain the voltage accumulated at
C5144 at a constance level.
After the charging voltage is divided and converted to a lower
voltage by R5417 and R5419, it is output to the SY1 circuit
board as the monitoring voltage VMONIT. When this VMONIT
voltage reaches a specified level at the SY1 circuit board, the
CHG signal is switched to Low and charging is interrupted.
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