UH8615

Preliminary

CMOS IC

UNISONICTECHNOLOGIESCO.,LTD

2 of 9

www.unisonic.com.tw

QW-R118-019.a



PIN CONFIGURATION

28

27

26

25

24

23

22

21

20

19

18

17

16

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

FB

COMP

N/C

BAT

DIVPAUSE

OSC

GND

PWMOUT

BOOST

PUMPOUT

QOUT

NOTON

FLT

FLTC

QOUT

ADJ

LPOWER

WARMUPV

LOADISENSE

N/C

WARMUPC

SLOPEC

BYPASS



PIN FUNCTION DESCRIPTIONS

PIN NO.

FUNCTION

DESCRIPTION

1

BYPASS

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.

2

SLOPEC

SLOPEC and WARMUPC is connected to capacitors to track lamp cool down and

warm-up. The capacitor connected to SLOPEC charges up to 5V with a rate controlled

current of 100nA.

3

WARMUPC

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

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.