UH8615 Datasheet, PDF (3/9 Pages) Unisonic Technologies – HID LAMP CONTROLLER

UH8615
Preliminary
CMOS IC
 PIN FUNCTION DESCRIPTIONS (Cont.)
PIN NO.
6
7
8
9
10
11
12
13
14
15
16
17
18
FUNCTION
WARMUPV
LPOWER
ADJ
QOUT
I_SET
V_O(SENSE)
FLTC
FLT
NOTON
QOUT
V_CC
PUMPOUT
BOOST
DESCRIPTION
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.
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.
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.
When operated with AC HID lamps, the QOUT pin is a logic output that toggles at OSC
frequency divided by 512.
Precise current is required for many functions of the UH8615. A resistor connected
from I_SET 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.
The V_O(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
V_O(SENSE) voltage reaches 5V, corresponding to the lamp voltage of 600V, the UTC
UH8615 will terminate PWM output. When the V_O(SENSE) voltage is outside the window of
83Mv and 2V, the lamp is either shorted, open or not lit.
the UTC UH8615 monitors the voltage on V_O(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.
if the voltage on the FLTC pin exceeds 5V, the FLT output goes high to V_CC. And it
indicates a serious system fault.
NOTON is pulled low When the voltage on V_O(SENSE) is within the 83mV ~ 2V window.
Otherwise NOTON is pulled high to V_CC
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.
V_CC is the main supply input to the UTC UH8615. all the functions are powered by the
V_CC and BOOST. V_CC 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.
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 V_CC to GND
at half of the OSC frequency.
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.
UNISONIC TECHNOLOGIES CO., LTD
www.unisonic.com.tw
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QW-R118-019.a