UH8615 Datasheet, PDF (2/9 Pages) Unisonic Technologies – HID LAMP CONTROLLER

UH8615
 PIN CONFIGURATION
BYPASS 1
SLOPEC 2
WARMUPC 3
N/C 4
LOADISENSE 5
WARMUPV 6
LPOWER 7
ADJ ⁸
QOUT 9
ISET 10
VO(SENSE) 11
FLTC 12
FLT 13
NOTON 14
Preliminary
28 5VREF
27 FB
26 COMP
25 N/C
24 BAT
23 ISENSEIN
22 DIVPAUSE
21 OSC
20 GND
19 PWMOUT
18 BOOST
17 PUMPOUT
16 VCC
15 _QOUT
CMOS IC
 PIN FUNCTION DESCRIPTIONS
PIN NO. FUNCTION
1
BYPASS
DESCRIPTION
The UTC UH8615 compensates for lamp temperature changes by varying the voltage
on the WARMUPC and SLOPEC capacitors. As the lamp warms up these two voltages
rises. And an internal circuit will calculate what power should be applied to the lamp.
When the HID lamp is turned off, the lamp will cool down at a certain rate, the two
voltage on the WARMUPC and SLOPEC capacitors should also discharge at a similarly
rate. In this way, if the lamp is restarted before the lamp is fully cooled down, the
controller will estimate the temperature of the lamp at the same time. So the correct
power for the lamp can be calculated.
A large capacitor connected to BYPASS supply the power for controlling the discharge
of the two capacitors. The value of the capacitor can be estimated by the following
formula:
Assuming a maximum BYPASS current of 5uA, a discharge time of 60s, and a
maximum allowable droop of 5V, the capacitor should be 60uF.
SLOPEC and WARMUPC is connected to capacitors to track lamp cool down and
2
SLOPEC
warm-up. The capacitor connected to SLOPEC charges up to 5V with a rate controlled
by the resistor connected to the I_SET. When V_CC is power off, SLOPEC discharges at a
current of 100nA.
the lamp temperature is estimated not only by the capacitor from SLOPEC to GND but
also by the voltage on a capacitor from WARMUPC to GND. This capacitor is charged
3
WARMUPC by a 200nA current source to 4.2V and by a 100nA current source from 4.2V to 10V
when the lamp is on, and discharged by 39nA current sink to 2.5V and 11nA current sink
to GND when the lamp is off.
5
LOADISENSE Lamp current regulation to supply correct lamp power at every lamp temperature.
UNISONIC TECHNOLOGIES CO., LTD
www.unisonic.com.tw
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QW-R118-019.a