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부품번호 | UBA3070 기능 |
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기능 | LED backlight driver IC | ||
제조업체 | NXP Semiconductors | ||
로고 | |||
전체 16 페이지수
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
NXP Semiconductors
UBA3070
LED backlight driver IC
7. Functional description
The UBA3070 is a monolithic driver IC for controlling the current through LED strings e.g.
45 green/blue/white LEDs connected in series making the UBA3070 IC especially suitable
as an LED driver.
The driver stage enables optimal performance for series connected LED strings in 0D, 1D
and 2D segmented Backlight Units (BLUs). Since the UBA3070 drives an external power
device, it can be used for all kinds of BLU designs ranging from high-power to low-power
LEDs, and high-voltage to low-voltage LED strings. Therefore, the UBA3070 is an
excellent driver solution for all types of LEDs and LCD screen sizes. Combining the
UBA3070 with suitable power devices means the quantity of drivers can be minimized by
optimizing the quantity of series LEDs.
Each driver stage consists of a buck converter operating in BCM with its peak level
determined by an external sense resistor. Since the peak and zero levels are fixed by
design, the converter behaves as a current source. This gives an average LED current
throughput that is half the peak value of that through the inductor. The ripple current
through the LEDs can be selected by connecting an external capacitor in parallel with the
LEDs.
7.1 Supply management and UVLO
As long as VCC is below the VCC(startup) level of typically 10 V, the supply current remains
below 600 μA. The UBA3070 IC activates the converter as soon as the voltage on the VCC
pin passes the VCC(startup) level. When the voltage on VCC pin drops below the UVLO
voltage typically 8.7 V the UBA3070 IC stops switching.
7.2 Current control and PWM
If the PWM input is HIGH (> 2 V) the converter is disabled and does not switch and, LED
current remains at zero. When the PWM input pin is LOW (< 0.5 V) the converter is
enabled and operates as follows.
The external Field-Effect Transistor (FET) is turned on and current in the inductor begins
to build up. During the charging phase of the inductor the current is sensed across an
external sense resistor. The internal driver turns off the external FET on detecting a
voltage level of 0.52 V at the SENSE pin. The inductor now starts to freewheel its current
through the external diode and starts discharging.
Following the discharge period the switch node rings. On detection of a valley or zero
voltage on the switch node the internal driver turns on the external FET. As the FET is at
zero current and minimal voltage, this results in minimal power losses and
ElectroMagnetic Interference (EMI). The conversion cycle is repeated as described
above, until the PWM input signal is driven high to disable the converter and steers the
LED current to zero.
If the PWM pin is open circuit or not connected, a fault condition is assumed and the
converter stops switching. Operation restarts as soon as the fault condition is removed.
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.
4 of 16
4페이지 NXP Semiconductors
UBA3070
LED backlight driver IC
10. Characteristics
Table 5. Characteristics
Tamb = 25 ° C; VCC = 15 V; all voltages are measured with respect to ground; currents are positive when flowing into the
UBA3070 IC; unless otherwise specified.
Symbol
Parameter
Conditions
Min Typ
Max Unit
VBR breakdown voltage
Supply voltage management (VCC pin)
VCC(startup)
start-up supply voltage
VCC(UVLO)
undervoltage lockout supply
voltage
650 -
9.3 10
8.1 8.7
-V
10.6 V
9.3 V
VCC(hys)
hysteresis of supply voltage
ICC(oper)
operating supply current
ICC(startup)
start-up supply current
ICC(prot)
protection supply current
Masking management (MASK pin)
VCC(startup) − VCC(UVLO)
no load on GATE pin
VCC < VCC(startup)
VCC > VCC(UVLO)
1.0 1.3
1.6 V
1.1 1.3
1.5 mA
--
600 μA
- 0.85 - mA
Vth(MASK)
threshold voltage on pin MASK
Vclamp(neg)(MASK) negative clamp voltage on pin
MASK
IMASK = −150 μA
50 100 150 mV
−0.5 −0.25 −0.05 V
Vclamp(pos)(MASK) positive clamp voltage on pin
MASK
IMASK = 250 μA
0.5 0.7
0.9 V
Istop(pos)(MASK)
tsup(xfmr_ring)
positive stop current on pin MASK
transformer ringing suppression start secondary stroke
time
54 60
1.1 1.5
66 μA
1.9 μs
Iprot(MASK)
Oscillator
protection current on pin MASK VMASK = 50 mV
−50[1] -
−10 nA
fosc(high)
high oscillator frequency
PWM duty cycle control (PWM pin)
VPWM is LOW
145 175
205 kHz
VIL(en)ILED(PWM) LED current enable LOW-level
input voltage on pin PWM
[2] -
-
0.5 V
VIH(dis)ILED(PWM) LED current disable HIGH-level
input voltage on pin PWM
[2] 2.0
-
-V
Iprot(PWM)
protection current on pin PWM
Valley switch (DRAIN pin)
VPWM = 1.5 V
−1.0[1] −0.8
−0.5 μA
(ΔV/Δt)vrec
valley recognition voltage change
with time
−85 -
+85 V/μs
td(vrec-swon)
valley recognition to switch-on
delay time
-
150[1]
-
ns
OCP (SENSE pin)
Vsense(max)
tPD
Vswp
tleb
Istartup(soft)
maximum sense voltage
propagation delay
short-winding protection voltage
leading edge blanking time
soft startup current
ΔV/Δt = 0.1 V/μs
ΔV/Δt = 0.5 V/μs
Rsense < 0.5 V
0.48 0.52
- 140
0.83 0.88
300 370
45 60
0.56 V
185 ns
0.95 V
440 ns
75 μA
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.
7 of 16
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