UNISONIC TECHNOLOGIES CO., LTD
UH8615
Preliminary
CMOS IC
HID LAMP CONTROLLER
DESCRIPTION
The UTC
UH8615
is suit for all lighting applications where HID
lamps are select, and designed for the demanding of fast turn on
requirements of automobile headlamps.
It integrates all of the functions required to control and drive
one HID lamp. A complete current mode pulse width modulation,
total fault protection, a lamp power regulator and temperature
compensation are integrated.
FEATURES
* Current Mode Control
* Fixed Frequency Operation
* Regulates Lamp Power and Temperature Compensation.
* High Current FET Drive Output
* Over-Current Protection.
* Over-Voltage Protection.
* Open and Short Protection.
* Operates Over Wide Battery Voltage Range: 5V ~ 18V
ORDERING INFORMATION
Order Number
UH8615L-D28-T
UH8615L-S28-R
Package
DIP-28
SOP-28
Packing
Tube
Tape Reel
MARKING
DIP-28
SOP-28
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QW-R118-019.a
UH8615
PIN CONFIGURATION
BYPASS
SLOPEC
WARMUPC
N/C
LOADISENSE
WARMUPV
LPOWER
ADJ
1
2
3
4
5
6
7
8
Preliminary
CMOS IC
28 5V
REF
27 FB
26 COMP
25 N/C
24 BAT
23 I
SENSEIN
22 DIVPAUSE
21 OSC
20 GND
19 PWMOUT
18 BOOST
17 PUMPOUT
16 V
CC
15 QOUT
QOUT 9
I
SET
10
V
O(SENSE)
11
FLTC 12
FLT 13
NOTON 14
PIN FUNCTION DESCRIPTIONS
FUNCTION
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
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
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.
Lamp current regulation to supply correct lamp power at every lamp temperature.
PIN NO.
1
BYPASS
2
SLOPEC
3
WARMUPC
5
LOADISENSE
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QW-R118-019.a
UH8615
PIN NO.
FUNCTION
Preliminary
CMOS IC
PIN FUNCTION DESCRIPTIONS (Cont.)
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.
6
WARMUPV
7
8
9
LPOWER
ADJ
QOUT
10
I
SET
11
V
O(SENSE)
12
FLTC
13
14
15
16
FLT
NOTON
QOUT
V
CC
17
PUMPOUT
18
BOOST
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UH8615
PIN NO.
FUNCTION
Preliminary
CMOS IC
PIN FUNCTION DESCRIPTIONS (Cont.)
DESCRIPTION
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.
Ground for IC is through this pin.
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
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.
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
keep lamp power constant. This current is sensed by a connection from I
SENSEIN
pin to a
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
limiting. It is limited 0.2V across the I
SENSEIN
resistor during normal operation and 0.4V
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
compensation to prevent oscillation. An external resistor from I
SENSEIN
to the current sense
resistor creates a voltage drop proportional to OSC voltage, which gives slope
compensation.
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.
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.
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.
The output of the internal 5V reference voltage that is used for setting currents and
thresholds and can also be used for other functions.
19
PWMOUT
20
21
GND
OSC
22
DIVPAUSE
23
I
SENSEIN
24
BAT
26
27
28
COMP
FB
5V
REF
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QW-R118-019.a
UH8615
BLOCK DIAGRAM
Preliminary
CMOS IC
DIVPAUSE
22
24- BAT
24
5V
50µA
OSC
21
100kHz
OSC
T
Q
390Hz
7 Bit Divider
50k
T
Q
Q
15
9
QOUT
QOUT
X1
10V
BOOST
18
50K
17
PUMPOUT
IC Power
ISENSEIN
COMP
23
26
R
S
X10
19
PWMOUT
+
-
R
R
+
-
R
R
Q
-
FB
27
+
2.5V
2V
-
+
-
delay
14
NOTON
VOUT SENSE
11
83mV +
250nA
V
CC
+
5V
SLOPEC
5V
0.5V
2
Q
R S
0.82V
+
-
-
+
-
+
-
5V
50nA
12
FLTC
X1
100nA
0.268V
5.6V From
Boost
4.2V
10V
100nA
11nA
0V
5V
13
FLT
LOAD ISENSE
LPOWER
WARMUPC
5
7
3
200nA
39nA
2.5V
20nA
Reference
6
WARMUPV
83k
10k
-
ADJ
8
+
-
+
Master
Bias
To Current Sinks
10
1
16
20
28
5VREF
ISET
BYPASS
V
CC
GND
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QW-R118-019.a
微控制器 MCU
