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PDF UBA2071 Data sheet ( Hoja de datos )
| Número de pieza | UBA2071 | |
| Descripción | Half bridge control IC | |
| Fabricantes | NXP Semiconductors | |
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UBA2071; UBA2071A
Half bridge control IC for CCFL backlighting
Rev. 01 — 23 June 2008
Product data sheet
1. General description
2. Features
The UBA2071 and UBA2071A are high voltage ICs intended to drive Cold Cathode
Fluorescent Lamps (CCFLs) or External Electrode Fluorescent Lamps (EEFLs) for
backlighting applications. They can drive a half bridge circuit made up of two NMOSFETs
with a supply voltage of up to 550 V, so the inverter can be supplied directly from a 400 V
PFC bus.
The UBA2071 and UBA2071A contain a controller, a level shifter, a bootstrap diode and
drivers for the external half bridge power switches. It also contains a low frequency PWM
generator, which can be used to control the brightness level of the lamps, using an analog
brightness/dimming control voltage. PWM dimming can also be realized, using a digital
PWM input signal. PWM dimming can be synchronized with other ICs. The lamp current is
controlled by means of a true zero voltage switching resonant control principle, ensuring
lowest possible switch losses in the half bridge power structure.
The UBA2071 is designed to be supplied by a ∆V/∆t supply from the half bridge circuit that
it drives. The IC itself needs little current and if the IC is off, a clamp protects the supply
voltage from getting too high.
The UBA2071A is designed to be supplied by a fixed 12 V supply. It has a lower supply
start voltage and no supply clamp.
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I Suitable for operating in a very wide inverter supply voltage range (up to 550 V DC).
I Integrated level shifter.
I Integrated bootstrap diode.
I Lamp current control by means of a true zero voltage switching resonant control
principle.
I Sample & Hold circuit, maintaining current control value during PWM lamp-off
situation.
I Separately definable time constants for current control loop and PWM dimming
attack/decay setting.
I Overvoltage control.
I Overcurrent protection.
I Ignition failure detection.
I Hard switching control.
I Arcing detection.
I Open/short pin protections on feedback pins.
I Integrated, programmable fault timer.
datasheet pdf - http://www.DataSheet4U.net/
1 page  
NXP Semiconductors
7. Pinning information
7.1 Pinning
UBA2071; UBA2071A
Half bridge control IC for CCFL backlighting
IFB 1
CIFB 2
VFB 3
CVFB 4
CSWP 5
CT 6
CF 7
IREF 8
CPWM 9
SGND 10
COMM 11
NONFAULT 12
UBA2071
24 GH
23 FS
22 SH
21 n.c.
20 n.c.
19 n.c.
18 GL
17 PGND
16 VDD
15 EN
14 PWMA
13 PWMD
014aaa099
Fig 2. Pin assignment SO24 and SSOP24 package (top view)
7.2 Pin description
Table 3.
Symbol
IFB
CIFB
VFB
CVFB
CSWP
CT
CF
IREF
CPWM
SGND
COMM
Pin description
Pin Description
Function
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1 current feedback input. Input signal for the lamp current control loop. Should be connected to a
voltage proportional to the lamp current.
2 current regulation
capacitor.
A capacitor must be connected between this pin and the signal ground. It
sets the time constant of the lamp current control loop.
3 voltage feedback input Input signal for the voltage control loop. Should be connected to a voltage
proportional to the transformer output voltage.
4 voltage regulation
capacitor
A capacitor must be connected between this pin and the signal ground. It
sets the time constant of the voltage control loop.
5 frequency sweep
capacitor
A capacitor must be connected between this pin and the signal ground. It
sets the time in which the HF frequency is swept up from regulation level to
the maximum frequency and back during PWM dimming.
6 fault timing capacitor
A capacitor must be connected between this pin and the signal ground. It
sets the time that a fault condition is allowed before the IC shuts down itself.
7 HF-oscillator timing
capacitor
A capacitor must be connected between this pin and the signal ground. It
sets the minimum switching frequency of the half bridge.
8 reference current output A 33 kΩ resistor must be connected between this pin and the signal ground.
The IC uses it to make accurate internal currents.
9 PWM timing capacitor If a capacitor is connected between this pin and the signal ground, it sets the
frequency of the PWM oscillator.
If this pin is connected to signal ground the internal PWM oscillator is
disabled.
10 signal ground
11 master / slave
communication
Via this pin the IC can communicate with a dedicated slave device.
UBA2071_A_1
Product data sheet
Rev. 01 — 23 June 2008
© NXP B.V. 2008. All rights reserved.
5 of 35
datasheet pdf - http://www.DataSheet4U.net/
5 Page 
NXP Semiconductors
UBA2071; UBA2071A
Half bridge control IC for CCFL backlighting
(H)2(EN)
EN
(H)1(EN)
(L)(EN)
0
GH VSH
GL
0
0.5 T
disabled
7.5 T
3 / fsw(min)
T
1 / fsw(max)
DC blocking capacitor charging
Fig 7. DC blocking capacitor charging mode
7.5 T
3 / fsw(min)
initial ignition sweep
and normal mode
014aaa252
Remark: Due to the nature of the charging sequence, VCblock will automatically be
charged to 0.5 × VHV (when given enough time). If the IC is kept in DC blocking capacitor
charging mode longer than necessary, VCblock will remain 0.5 × VHV. Therefor the time
constant made by R1 and C1 in example A in Figure 6, is not critical. However, since
VCblock cannot become more than 0.5 × VHV, it is important to take a lower target value for
VCblock than 0.5 × VHV (with enough margin) in examples B and C of Figure 6, otherwise
the IC may get stuck in DC blocking capacitor charging mode.
8.8 Lamp (re-)ignition
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The IC starts at its maximum switching frequency fsw(max). The lamp current and the lamp
voltage control loops are enabled. The frequency is swept down towards the minimum
frequency fsw(min), see Figure 9. During this initial ignition frequency sweep the lamp
voltage will increase as the frequency comes closer to the resonant frequency of the
unloaded resonance circuit. Once the ignition voltage Vign is reached the lamps will ignite
and the lamp voltage will drop4 to the voltage of the loaded resonance curve, see
Figure 8.
4. For CCFLs only.
UBA2071_A_1
Product data sheet
Rev. 01 — 23 June 2008
© NXP B.V. 2008. All rights reserved.
11 of 35
datasheet pdf - http://www.DataSheet4U.net/
11 Page | ||
| Páginas | Total 35 Páginas | |
| PDF Descargar | [ Datasheet UBA2071.PDF ] | |
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