AN8049 Panasonic Semiconductor, AN8049 Datasheet - Page 17

• Manufacturer Part Number: AN8049
• Description: 1.8-volt 3-channel step-up/ step-down/ and polarity inverting DC-DC converter control IC
• Manufacturer: Panasonic Semiconductor

Voltage Regulators
[4] Function descriptions (continued)
10. Output 3 block
11. CTL block
7. Low input voltage malfunction prevention circuit (U.V.L.O.)
8. PWM comparators
9. Output 1 and output 2 blocks
Application Notes (continued)
power supply voltage falls during power on or power off.
the supply voltage level. While the supply voltage is rising, this circuit cuts off the output drive transistor until the
reference voltage reaches 1.67 V. It also sets the dead-time to 100% and at the same time holds the S.C.P. pin (pin
23) and the DT pins (pins 1, 2, and 24) at 0 V, and the OSC pin (pin 15) at about 1.2 V.
both of the corresponding FB pin (pins 18, 20, or 22) and the corresponding DT pin (pins 1, 2, or 24).
a higher level than both of the FB2 pin (pin 20) and the DT2 pin (pin 1).
between the corresponding DT pin and ground, and can be set to a value higher than 86% by inserting a resistor
between the corresponding DT pin and the V
if a capacitor is inserted between the DT pin and ground.
can be set up freely by connecting current setting resistors to the RB pins.
regulation can be set up freely by connecting current setting resistors to the RB2 pin.
This circuit protects the system against degradation or destruction due to incorrect control operation when the
The low input voltage malfunction prevention circuit detects the internal reference voltage that changes with
The PWM comparators control the on-period of the output pulse according to their input voltage.
The output transistors are turned on during periods when the OSC pin (pin 15) triangular wave is lower than
The PWM 2 circuit turns the output transistor on during periods when OSC pin (pin 15) triangular wave is at
The maximum duty is set to 86% internally, but it can be set to a value lower than 86% by inserting a resistor
The IC's soft start function operates to gradually increase the width of the output pulse on-period during startup
These output circuits have a totem pole structure. A constant-current source output with good line regulation
These circuits can provide a constant-current source output of up to 50 mA.
This output circuit has an open collector structure.
An output current of up to 50 mA can be provided, and the output pin has a breakdown voltage of 15 V.
The CTL block output circuit also has a totem pole structure. A constant-current source output with good line
The CTL block can provide a constant-current source output of up to 50 mA.
REF
pin.
AN8049FHN
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