UH8615L-S28-R datasheet(3/9 Pages) UTC

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UH8615

Preliminary

CMOS IC

UNISONICTECHNOLOGIESCO.,LTD

3 of 9

www.unisonic.com.tw

QW-R118-019.a



PIN FUNCTION DESCRIPTIONS (Cont.)

PIN NO.

FUNCTION

DESCRIPTION

WARMUPV

The UTC UH8615 in herents a buffer amplifier which buffers the voltage on WARMUPC

and processes it to WARMUPV. because of the impedance on WARMUPC is too high.

The voltage of WARMUPC can’t be used to modulate the signal fed to the error amplifier

through FB directly. So after processed by the buffer, the signal of WARMUPV is

appropriate for driving FB.

LPOWER

the amplifier which amplifies the difference between the desired load current and the

actual load current can generate an output signal on LPOWER. The signal feeds to the

error amplifier.

ADJ

The voltage on the pin controls the ratio of cold lamp peak current to warmed-up lamp

peak current. It is selected by connecting a resistor from ADJ to GND.

QOUT

When operated with AC HID lamps, the QOUT pin is a logic output that toggles at OSC

frequency divided by 512.

ISET

Precise current is required for many functions of the UH8615. A resistor connected

from ISET to GND can adjust the current. A resistor of 100K is for the normal operating

current. Lower value increases the internal currents. The functions of WARMUPC

charging and discharging, SLOPEC charging and discharging, FLTC charging and

discharging, and error amplifier bandwidth are influenced by the resistor.

VO(SENSE)

The VO(SENSE) is used to sense lamp voltage. The voltage across the lamp is between

60V to 110V in a normal operation. When the voltage is higher than 300V, it may break

down the lamp. It is desirable to limit the voltage on the starter input to 600V maximum.

And the voltage less than 10V indicates a shorted lamp.

The voltage of the V O(SENSE) is between 83Mv and 2V corresponding to the lamp voltage

is between 10V and 240V, when the lamp is in normal operation. If the

VO(SENSE) voltage reaches 5V, corresponding to the lamp voltage of 600V, the UTC

UH8615

will terminate PWM output. When the VO(SENSE) voltage is outside the window of

83Mv and 2V, the lamp is either shorted, open or not lit.

FLTC

the UTC UH8615 monitors the voltage on VO(SENSE). This voltage is proportional to lamp

voltage. It is compared to an internal 83 mV lower threshold and 2V upper threshold. If it

is too high or too low, the lamp is in abnormal condition. At that time, the IC will pull up

on FLTC with a current of approximately 250nA. If the fault remains, the voltage on the

external FLTC capacitor will over 5V. then the controller declares a catastrophic fault

and shuts the circuit down. It will last until power is removed from BOOST.

If the fault clears before the capacitor reaches 5V, the capacitor discharge down to 0V

with a current of approximately 50nA. It is five times longer than charging.

FLT

if the voltage on the FLTC pin exceeds 5V, the FLT output goes high to VCC. And it

indicates a serious system fault.

NOTON

NOTON is pulled low When the voltage on VO(SENSE) is within the 83mV ~ 2V window.

Otherwise NOTON is pulled high to VCC

QOUT

The pin QOUT is a logic output, which toggles at the OSC frequency divided by 512,

180 degrees out of phase with the QOUT pin.

VCC

VCC is the main supply input to the UTC UH8615. all the functions are powered by the

VCC and BOOST. VCC will be clamped to 6.8V by an external zener diode. And it will

keep as close to 6.8V as practical with a low value resistor to the supply.

PUMPOUT

In normal operation, a voltage of approximately 10V which connected to BOOST supply

power for many functions. This voltage is generated by a voltage doubler using the

PUMPOUT pin. The out of PUMPOUT is a square wave, which swings from VCC to GND

at half of the OSC frequency.

BOOST

This pin supply a approximately 10V voltage for the functions of the device operate. And

the 10v voltage is generated by a voltage doubler using PUMPOUT as an AC signal and

external diodes switches.

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