UH8615

Preliminary

CMOS IC

UNISONICTECHNOLOGIESCO.,LTD

4 of 9

www.unisonic.com.tw

QW-R118-019.a



PIN FUNCTION DESCRIPTIONS (Cont.)

PIN NO.

FUNCTION

DESCRIPTION

19

PWMOUT

The output of the PWMOUT is the signal output of the pulse width modulator. it is used to

command a power MOSFET switch. In normal PWM-OUT can be directly connected to

the gate of an N-channel power MOSFET. And if the lead between the UTC UH8615 and

the MOSFET is longer than a few cm. A 10 ohm resistor from PWMOUT to the MOSFET

gate may be required.

20

GND

Ground for IC is through this pin.

21

OSC

The frequency of the PWM in the UTC UH8615 can be generated by the pin. A 200pF

capacitor from OSC to GND programs the PWM frequency at 100kHz. In fact the actual

oscillator frequency is determined by both the capacitor from OSC to GND and the

resistor from ISET to GND

22

DIVPAUSE

The QOUT and QOUT outputs switch lamp polarity in an AC ballast. when the lamp is

being lit, It is important to stop polarity switching to keep the arc across the electrodes

can form in the correct place. A high voltage on DIVPAUSE can stop the internal circuit

generates the QOUT and QOUT signals.

Connect a resistor from NOTON to DIVPAUSE and a capacitor from DIVPAUSE to GND,

will stop the divider when the lamp is being lit and start after the lamp has lit.

23

the UTC UH8615 HID Controller is built in a power regulation algorithm that can compute

a function of the lamp current and voltage. It computes the appropriate battery current to

current sense resistor. This current sensed pulse width modulation scheme is often

referred to as current mode control. The UTC UH8615 also contains peak input current

during starting. The period from starting to normal operation is accomplished by the rise of

the WARMUPC capacitor. As the current mode control has a disadvantage that the loop

will enter chaotic oscillations at high duty cycle, the UTC UH8615 inherent the slope

resistor creates a voltage drop proportional to OSC voltage, which gives slope

compensation.

24

BAT

This input can detect excessively high input voltage and will shut down the IC if the input

voltage exceeds a set voltage. When connect BAT to a voltage divider across the input

supply, in order to protect the IC in the quite event, please keep divider impedance higher

than 10k.

26

COMP

COMP is drived by the amplifier which senses the difference between FB and 2.5V. a

capacitor should be connected from COMP to FB to keep the system stable.

27

FB

The FB pin is the inverted input of error amplifier that senses the differences between the

commanded lamp power and desired lamp power. The output of the error amplifier drives

the comp.

28

The output of the internal 5V reference voltage that is used for setting currents and

thresholds and can also be used for other functions.