AOZ1960
Multi-String Boost White LED Driver
General Description
The AOZ1960 is a high-efficiency boost regulator with
integrated 55V boost switch and 30V input protection
switch. It is designed to drive 6 parallel strings of multiple
series-connected white LEDs for LCD backlight
applications. The current of each string is individually
regulated by an internal current regulator. The AOZ1960
has a wide input voltage range from 7V to 24V. The
maximum LED current can be adjusted from 15mA to
30mA using an external resistor connected to ISET pin.
The AOZ1960 support two dimming control modes to
enable a wide variety of applications. In analog dimming
mode, the LED current can be directly adjusted through
ABRT pin to achieve 10% to 100% brightness range.
In digital dimming mode, a PWM signal on DBRT controls
the brightness by turning the current regulators on and
off. The brightness is proportional to the duty cycle of the
PWM signal.
The AOZ1960 has multiple features to protect the
regulator under fault conditions. An internal 30V input
protection switch protects against catastrophic failure
conditions such as output short-circuits. A separate
over-voltage protection (OVP) loop limits the output
voltage if LED strings fail open. Cycle-by-cycle
over-current protection (OCP) limits the peak inductor
current. Built-in soft-start minimizes the inrush current
during startup. Thermal shutdown provides another level
of protection.
The integrated 55V power MOSFET reduces the cost
and external component count, while allowing output
voltages as high as 55V. Low dropout voltage of LED
current regulator (500mV) minimizes power loss. In
addition, automatic pulse skipping operation improves
efficiency at light loads. The AOZ1960 features
programmable switching frequency allows for trade-offs
between solution size and electrical efficiency.
The AOZ1960 is available in a thermally enhanced
24-pin 7mm x 4mm DFN package and operates over the
temperature range of -40°C to +85°C.
Features
7V to 24V input voltage range
Integrated 30V input switch
55V/2A internal N-channel MOSFET
Six parallel strings
Programmable switching frequency
500mV low dropout current regulator
Resistor programmable maximum LED current
Analog dimming via ABRT pin
Digital PWM dimming via DBRT pin
Dimming range with 8-bit resolution
Cycle-by-cycle current limit
Open and short LED protection
Output over-voltage and short protection
Thermal overload protection
Internal Soft-start
7mm x 4mm DFN package
Applications
Notebook PC display
Tablet PC display
Desktop monitors
Portable DVD players
Digital photo frames
Car navigation display
Rev. 1.0 August 2010
www.aosmd.com
Page 1 of 20
AOZ1960
Pin Description
Pin Number
1
2
3
4
5, 8, 19
6
7
9
Pin Name
IN
EN
BIAS
ISET
AGND
COMP
FSEL
ABRT
Input Supply Pin.
Pin Function
Enable Input. Pull EN above 2V to enable the LED driver and pull EN below 0.8V to disable
the LED driver.
Internal 5V Linear Regulator Output. Connect a minimum 0.22μF ceramic capacitor from
BIAS to ground.
LED Current Set Pin. Connect a resistor from ISET to ground to set the nominal LED
current (100% brightness) for each string.
Analog ground.
Compensation Pin. COMP is the output of the internal error amplifier. Connect a
RC network from COMP to ground to compensate the control loop.
Frequency Select Pin. Connect FSEL to ground via a resistor to set the switching
frequency.
Analog Brightness Control Input. ABRT controls the LED brightness by adjusting the LED
current in proportion to ABRT voltage. The input range of ABRT is between 0 to 2V. When
VBRT is below 0.2V, the LED current is 10% of the nominal setting. When BRT voltage is
2V or above, the LED current is 100% of the normal setting.
PWM Brightness Control Input. DBRT controls the LED brightness by turning the LED on
and off using a PWM signal. The brightness is proportional to the PWM duty.
Fault Output. FLT is an open-drain output. Connect a pull-up resistor between BIAS and
FLT.
Over-voltage protection Input. Use a voltage divider to set the boost regulator output
over-voltage protection threshold.
Boost Regulator Switching Pin. LX is the drain of the 55V internal boost switch.
Power Ground.
Internal LED Current Regulator 1 Input.
Internal LED Current Regulator 2 Input.
Internal LED Current Regulator 3 Input.
Internal LED Current Regulator 4 Input.
Internal LED Current Regulator 5 Input.
Internal LED Current Regulator 6 Input.
Boost Regulator Input Pin. LIN is drain of the input protection switch.
10
11
12
13, 14
15
16
17
18
20
21
22
23, 24
DBRT
FLT
OVP
LX
PGND
LED6
LED5
LED4
LED3
LED2
LED1
LIN
Rev. 1.0 August 2010
www.aosmd.com
Page 4 of 20
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