Features

• Input voltage range: 2.7V to 5.5V
• Drive up to 60 LEDs (10S6P)
• High efficiency LED driver, up to 90%
• High frequency step-up converter (1000kHz)
• Integrated 40V power MOSFET
• Integrated 6-channel current sinks
− Up to 30mA/ch
− 0.5% Typ. current matching
− 2% Typ. current accuracy at 20mA
• Wide input PWM dimming frequency range
− 300Hz to 30KHz
• Programmable Mixed-Mode Dimming controls
− Mixed analog dimming and PWM dimming
− Selectable transition point :
25% or 12.5% input PWM duty cycle
− Selectable output PWM dimming
frequency : fixed 62.5kHz or following input
PWM dimming frequency
− Channel current phase shift in fixed
62.5kHz output PWM dimming mode
• Input PWM glitch filter
• LED open/short protection
• Adjustable over-voltage protection
• Cycle-by-cycle inductor current limit (2.5A)
• 0.1 μA shutdown current
• TQFN33-16 and WLCSP-16 Package
• RoHS and Green Compliant
• -40°C to +85°C Temperature Range

Applications

• Tablet Backlight
• Netbook/Notebook Backlight
• Portable media players

Brief Description

KTD3156B is the ideal power solution for LED backlighting
in medium to large size LCD panels. It is a highly integrated
step-up DC-DC converter with input voltage from 2.7V to
5.5V, accommodating 1-cell lithium ion batteries or 5V
supply. KTD3156B integrates a 40V power MOSFET as
well as six current sinks, which results in a simpler and
smaller solution with fewer external components. High
switching frequency allows the use of a smaller inductor
and capacitor to further reduce the solution size.
Each of the six current sinks regulates up to 30mA. With a
40V rated output, each string of the boost can connect up
to 10 LEDs in series, for a total of 60 LEDs.
KTD3156B features mixed-mode dimming, which switches
between PWM dimming at low dimming duty cycle and
analog (DC current) dimming at high dimming duty cycle to
increase the total power efficiency. The transition point of
these two modes is programmable to 12.5% or 25% PWM
duty cycle. The PWM dimming mode’s output PWM
dimming frequency can be programmed to fixed 62.5kHz
or following input PWM dimming frequency. For fixed
62.5kHz output PWM dimming, phase shift function is
implemented among these six channels to further lower the
input current ripple and output voltage ripple.
Various protection features are built into KTD3156B,
including cycle-by-cycle input current limit protection,
output over-voltage protection, LED fault (open or short)
protection and thermal shutdown protection. The leakage
current in shutdown mode is 0.1μA.
KTD3156B is available in a RoHS and Green compliant
16-lead 3 x 3 x 0.75mm ThinQFN or 16-lead 1.65mm x
1.65mm WLCSP package.