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UBA2014T/N1,518

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P19
UBA2014_4 © NXP B.V. 2008. All rights reserved.
Product data sheet Rev. 04 — 16 October 2008 4 of 19
NXP Semiconductors
UBA2014
600 V driver IV for HF fluorescent lamps
7. Pinning information
7.1 Pinning
7.2 Pin description
Fig 2. Pin configuration (SO16) Fig 3. Pin configuration (DIP16)
UBA2014T
CT CSN
CSW CSP
CF VREF
IREF LVS
GND ACM
GL SH
V
DD
GH
PCS FV
DD
001aad405
1
2
3
4
5
6
7
8
10
9
12
11
14
13
16
15
UBA2014P
CT CSN
CSW CSP
CF VREF
IREF LVS
GND ACM
GL SH
V
DD
GH
PCS FV
DD
001aad486
1
2
3
4
5
6
7
8
10
9
12
11
14
13
16
15
Table 3. Pin description
Symbol Pin Description
CT 1 preheat timer output
CSW 2 input of voltage controlled oscillator
CF 3 voltage controlled oscillator output
IREF 4 internal reference current input
GND 5 ground
GL 6 gate output for the low-side switch
V
DD
7 low-voltage supply
PCS 8 preheat current sensor input
FV
DD
9 floating supply voltage; supply for high-side switch
GH 10 gate output for the high-side switch
SH 11 source for the high-side switch
ACM 12 capacitive mode input
LVS 13 lamp voltage sensor input
VREF 14 reference voltage output
CSP 15 positive input for the average current sensor
CSN 16 negative input for the average current sensor
UBA2014_4 © NXP B.V. 2008. All rights reserved.
Product data sheet Rev. 04 — 16 October 2008 5 of 19
NXP Semiconductors
UBA2014
600 V driver IV for HF fluorescent lamps
8. Functional description
8.1 Start-up state
Initial start-up can be achieved by charging the low-voltage supply capacitor C7
(see Figure 8) via an external start-up resistor. Start-up of the circuit is achieved under the
condition that both half bridge transistors TR1 and TR2 are non-conductive. The circuit
will be reset in the start-up state. If the low-voltage supply (V
DD
) reaches the value of
V
DD(start)
the circuit will start oscillating. A DC reset circuit is incorporated in the High-Side
(HS) driver. Below the lockout voltage at the FV
DD
pin the output voltage (V
GH
− V
SH
) is
zero. The voltages at pins CF and CT are zero during the start-up state.
8.2 Oscillation
The internal oscillator is a Voltage Controlled Oscillator (VCO) circuit which generates a
sawtooth waveform between the V
CF(high)
level and 0 V. The frequency of the sawtooth is
determined by capacitor C
CF
, resistor R
IREF
, and the voltage at pin CSW. The minimum
and maximum switching frequencies are determined by R
IREF
and C
CF
; their ratio is
internally fixed. The sawtooth frequency is twice the half bridge frequency. The UBA2014
brings the transistors TR1 and TR2 into conduction alternately with a duty cycle of
approximately 50 %. An overview of the oscillator signal and driver signals is illustrated in
Figure 4. The oscillator starts oscillating at f
max
. During the first switching cycle the
Low-Side (LS) transistor is switched on. The first conducting time is made extra long to
enable the bootstrap capacitor to charge.
8.3 Adaptive non-overlap
The non-overlap time is realized with an Adaptive Non-overlap circuiT (ANT). By using an
adaptive non-overlap circuit, the application can determine the duration of the non-overlap
time and make it optimum for each frequency; see Figure 4. The non-overlap time is
determined by the slope of the half bridge voltage, and is detected by the signal across
resistor R16 which is connected directly to pin ACM. The minimum non-overlap time is
internally fixed. The maximum non-overlap time is internally fixed at approximately 25 %
of the bridge period time. An internal filter of 30 ns is included at the ACM pin to increase
the noise immunity.
8.4 Timing circuit
A timing circuit is included to determine the preheat time and the ignition time. The circuit
consists of a clock generator and a counter.
The preheat time is defined by C
CT
and R
IREF
and consists of 7 pulses at C
CT
; the
maximum ignition time is 1 pulse at C
CT
. The timing circuit starts operating after the
start-up state, as soon as the low supply voltage (V
DD
) has reached V
DD(start)
or when a
critical value of the lamp voltage (V
lamp(fail)
) is exceeded. When the timer is not operating
C
CT
is discharged to 0 V at 1 mA.
UBA2014_4 © NXP B.V. 2008. All rights reserved.
Product data sheet Rev. 04 — 16 October 2008 6 of 19
NXP Semiconductors
UBA2014
600 V driver IV for HF fluorescent lamps
8.5 Preheat state
After starting at f
max
, the frequency decreases until the momentary value of the voltage
across sense resistor R14 reaches the internally fixed preheat voltage level (pin PCS). At
crossing the preheat voltage level, the output current of the
Preheat Current Sensor (PCS) circuit discharges the capacitor C
CSW
, thus raising the
frequency. The preheat time begins at the moment that the circuit starts oscillating. During
the preheat time the Average Current Sensor (ACS) circuit is disabled. An internal filter of
30 ns is included at pin PCS to increase the noise immunity.
8.6 Ignition state
After the preheat time the ignition state is entered and the frequency will sweep down due
to charging of the capacitor at pin CSW with an internally fixed current; see Figure 5.
During this continuous decrease in frequency, the circuit approaches the resonant
frequency of the load. This will cause a high voltage across the load, which normally
ignites the lamp. The ignition voltage of a lamp is designed above the V
lamp(fail)
level. If the
lamp voltage exceeds the V
lamp(fail)
level the ignition timer is started.
8.7 Burn state
If the lamp voltage does not exceed the V
lamp(max)
level the voltage at pin CSW will
continue to increase until the clamp level at pin CSW is reached; see Figure 5. As a
consequence the frequency will decrease until the minimum frequency is reached.
When the frequency reaches its minimum level it is assumed that the lamp has ignited and
the circuit will enter the burn state. The ACS circuit will be enabled. As soon as the
averaged voltage across sense resistor R14, measured at pin CSN, reaches the reference
level at pin CSP, the average current sensor circuit will take over the control of the lamp
current. The average current through R14 is transferred to a voltage at the voltage
controlled oscillator and regulates the frequency and, as a result, the lamp current.
8.8 Lamp failure mode
8.8.1 During ignition state
If the lamp does not ignite, the voltage level increases. When the lamp voltage exceeds
the V
lamp(max)
level, the voltage will be regulated at the V
lamp(max)
level; see Figure 6.
When the V
lamp(fail)
level is crossed the ignition timer has already started. If the voltage at
pin LVS is above the V
lamp(fail)
level at the end of the ignition time the circuit stops
oscillating and is forced into the Power-down mode. The circuit will be reset only when the
supply voltage is powered down.
8.8.2 During burn state
If the lamp fails during normal operation, the voltage across the lamp will increase and the
lamp voltage will exceed the V
lamp(fail)
level; see Figure 7. At that moment the ignition timer
is started. If the lamp voltage increases further it will reach the V
lamp(max)
level. This forces
the circuit to reenter the ignition state and results in an attempt to re-ignite the lamp. If
during restart the lamp still fails, the voltage remains high until the end of the ignition time.
At the end of the ignition time the circuit stops oscillating and the circuit will enter the
Power-down mode.
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P19

UBA2014T/N1,518

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Manufacturer:
NXP Semiconductors
Description:
Display Drivers & Controllers TL BALLAST
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