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PDF UBA3070 Data sheet ( Hoja de datos )
| Número de pieza | UBA3070 | |
| Descripción | LED backlight driver IC | |
| Fabricantes | NXP Semiconductors | |
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UBA3070
LED backlight driver IC
Rev. 3 — 9 December 2010
Product data sheet
1. General description
The UBA3070 driver IC is the first member of a first generation of power-efficient LED
backlight driver ICs. Highly efficient, flexible and reliable LED drivers can easily be
designed using the UBA3070 control IC.
2. Features and benefits
Switch-mode buck controller that drives strings of LEDs up to 600 V power-efficiently
Controller with power-efficient Boundary Conduction Mode (BCM) operation:
Virtually no reverse recovery losses in freewheel diode
Zero Current Switching (ZCS) at switch, switch-on
Zero voltage or valley switching at switch, switch-on
Minimal required inductance value and size
Suitable for direct Pulse Width Modulation (PWM) dimming
Fast transient response through cycle-by-cycle current control, thereby:
Preventing over or undershoots in the Light Emitting Diode (LED) current
Enabling efficient PWM dimming by quickly turning the converter on and off and
thus removing the need for extra dimming switches and high-side drivers
Single controlled input voltage required for all UBA3070 driven LED strings in RGB or
white backlighting units
No binning on LED forward voltage required
Protections:
UnderVoltage LockOut (UVLO)
Leading Edge Blanking (LEB)
OverCurrent Protection (OCP)
OverTemperature Protection (OTP)
Low cost LED driver solution:
No fast-switching Schottky diode required due to ZCS
No dimming switch or high-side driver required for PWM dimming
Operates with smaller inductor then a comparable fixed-frequency Continuous
Conduction Mode (CCM) controller
3. Applications
The UBA3070 is suitable for high voltage LED lighting application:
LED backlighting in LCD televisions and monitors
General lighting applications
The UBA3070 application is most efficient when driving long LED strings
1 page  
NXP Semiconductors
UBA3070
LED backlight driver IC
7.3 Masking and valley switching
The MASK pin ensures that switch-on of the converter is at a valley during ringing and not
at a peak during freewheeling of the inductor. If the voltage level at the MASK pin is above
100 mV, then switch-on of the switching FET is prevented. If the voltage level is below
100 mV, then switch-on prevention of the FET is released and at the moment of valley
detection the FET is turned on. The signal for the MASK pin can be derived from the
signal at the switch node as shown in Figure 2. The current flowing into the MASK pin
must be lower than the typical stop current of 60 μA.
If the MASK pin is open circuit or not connected, a fault condition is assumed and the
converter stops operating immediately. Operation restarts as soon as the fault condition is
removed.
7.4 Conversion frequency
The maximum conversion frequency of the UBA3070 is limited to 175 kHz. However, due
to production spread, the maximum conversion frequency of an individual UBA3070
sample can be as low as 145 kHz. Therefore, an inductance value must be selected so
that the applications conversion frequency always remains below 145 kHz after taking into
account variations due to the supply voltage, LED string voltage and component spread.
There is no limitation for the minimum conversion frequency.
7.5 Minimum on-time
The LEB time, typically 370 ns is a fixed delay that determines the minimum on-time of the
controller. The LEB time prevents the MOSFET switch from switching off unintentionally
(due to coupling to the sense node) directly after the start of a conversion cycle.
7.6 OverCurrent Protection (OCP)
As the converter acts as a current source it is self-protected from overcurrent by an extra
level of protection, i.e. a second trip level of typically 0.88 V applied to the short-winding/
sense node as shown in Figure 1. This second trip level is designed to protect the
convertor against short-circuits in external components e.g. in the diodes, inductors,
capacitors and/or LEDs. If a short-circuit is detected the convertor stops switching.
7.7 OverTemperature Protection (OTP)
OTP is provided in the UBA3070 IC and functions as follows. When the junction
temperature exceeds the thermal shutdown temperature of typically 140 °C the converter
stops switching.
7.8 Driver
The driver circuit to the gate of the power FET has a current sourcing capability of
approximately 135 mA and a current sinking capability of 560 mA. This capability means
the FET operates more efficiently with fast switch-on and switch-off cycles. A low driver
source current has been chosen to limit the ΔV/Δt at switch-on thereby reducing EMI and
voltage spikes across Rsense.
UBA3070
Product data sheet
All information provided in this document is subject to legal disclaimers.
Rev. 3 — 9 December 2010
© NXP B.V. 2010. All rights reserved.
5 of 16
5 Page 
NXP Semiconductors
UBA3070
LED backlight driver IC
14. Revision history
Table 7. Revision history
Document ID
Release date Data sheet status
Change notice Supersedes
UBA3070 v.3
Modifications:
20101209
Product data sheet
• Minor updates.
-
UBA3070 v.2
UBA3070 v.2
Modifications:
20080212
Product data sheet
-
UBA3070 v.1
• The minimum value for junction temperature has been updated in Table 3.
UBA3070 v.1
20080605
Product data sheet
-
-
UBA3070
Product data sheet
All information provided in this document is subject to legal disclaimers.
Rev. 3 — 9 December 2010
© NXP B.V. 2010. All rights reserved.
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