XC9116
Series
Step-Up DC/DC Converter-Backlight LED Driver
ETR0407-002
■GENERAL
DESCRIPTION
The XC9116 series is a fixed frequency, constant current step-up DC/DC converter ideal for driving LEDs used in backlighting
applications such as cellular phones, PDAs and digital cameras. Output voltage of up to 17.5V can be derived, therefore, four
white LEDs in series can be driven. Since an LED current can be set by an external resistor when LEDs are in-series
connection, all white LEDs can be turned on equably. A network of two parallel legs with three in each LED can be also
driven. Luminance of the LEDs is controlled by changing the duty cycle of a PWM signal applied to the CE pin. Efficiency is
high with the low feedback reference voltage ensuring the R
LED
losses are minimal. In addition, an internal MOSFET with an
R
DSON
of 2.0
Ω
is used. A low profile and small board area solution can be achieved using a chip coil and an ultra small
ceramic output capacitor (C
L
) of 0.22μF as a result of the high 1.0MHz switching frequency.
The 'B' type of XC9116 has an additional fault detection circuit. If the LEDs are disconnected or damaged, excess or run away
output voltage is prevented by stopping the drive of the internal MOSFET.
■APPLICATIONS
●For
White LED drivers
●Mobile
phones, PHS
●PDAs
●Digital
still cameras
■FEATURES
: 2.5V ~ 6.0V
: Up to 17.5V externally set-up
: Reference voltage 0.2V +5%
Oscillation Frequency
: 1.0MHz,
±20%
ON Resistance
: 2.0Ω
Efficiency
: 86% (XC9116B Type)
: 84% (XC9116D Type)
(V
IN
=3.6V, I
LED
=20mA when
driving 3 white LEDs in series)
Control
: PWM control
Standby current
: ISTB=1.0μA (MAX.)
Load Capacitor
: 0.22μF, ceramic
Lx Limit Current
: 325mA
Lx Overvoltage Limit
: XC9116B series
No Lx Overvoltage Limit
: XC9116D series
Package
: SOT-25 (SOT-23-5), USP-6B
Input Voltage Range
Output Voltage Range
■TYPICAL
APPLICATION CIRCUIT
SD
XB0ASB03A1B
VIN
2.5V~6.0V
L:22uH
VLF3010A
VIN
Lx
■TYPICAL
PERFORMANCE
CHARACTERISTICS
●XC9116B
Type
CIN
1uF
CL
0.22uF
CE
100Hz to
10kHz
FB
VSS
R
LED
10ohm
20mA
1/23
TOREX [ TOREX SEMICONDUCTOR ]
