LDS8865
6-Channel Ultra Low Dropout LED Driver
FEATURES
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Ultra low dropout PowerLite Current
Regulator
Multi-mode charge pump: 1x, 1.5x, 2x
Drives up to 6 LEDs at 32mA each
Factory preset current value at each LED
bank
PWM brightness control with up to 25,000:1
dimming range at 200 Hz
Power efficiency up to 94%
Low noise input ripple in all charge pump
modes
Low current shutdown mode
Soft start and current limiting
Short circuit protection
Thermal shutdown protection
Available in 3 x 3 x 0.8 mm 16-pin TQFN
package
voltage that can drive up to six LEDs. The ultra low
dropout PowerLite Current Regulator increases
device’s efficiency up to 94%.
The PWM1/PWM2 logic inputs function as a chip
enable and a PWM mode LED brightness control.
PWM1 pin contorls LEDA and LEDB banks with four
LEDs, while PWM2 controls bank with two LEDs.
The maximum LEDs current is factory preset Every
LED bank with two LEDs each is programmable
separately in the range from 0.5 to 32mA in 0.5mA
steps.
Low noise input ripple is achieved by operating at a
constant switching frequency which allows the use of
small external ceramic capacitors. The multi-
fractional charge pump supports a wide range of
input voltages from 2.7V to 5.5V.
The device is available in in 16-lead TQFN 3mm x
3mm package with a max height of 0.8mm.
APPLICATION
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LCD Display Backlight
Cellular Phones
Digital Still Cameras
Handheld Devices
DESCRIPTION
The LDS8865 is a high efficiency multi-mode
fractional charge pump with ultra low feedback
TYPICAL APPLICATION CIRCUIT
© 2009 IXYS Corp.
Characteristics subject to change without notice
1
Doc. No. 8865DS, Rev. N2.1
LDS8865
ABSOLUTE MAXIMUM RATINGS
Parameter
Vin, LEDx, C1±, C2± voltage
Vout voltage
PWM1, PWM2 voltage
Storage Temperature Range
Junction Temperature Range
Lead Temperature
Rating
6
6
Vin + 0.7V
-65 to +160
-40 to +125
300
Unit
V
V
V
°C
°C
°C
RECOMMENDED OPERATING CONDITIONS
Parameter
Vin
Ambient Temperature Range
Rating
2.7 to 5.5
-40 to +85
Unit
V
°C
ELECTRICAL OPERATING CHARACTERISTICS
(Over recommended operating conditions unless specified otherwise) Vin = 3.6V, C1 = C2 = 0.22 µF, C
IN
= C
OUT
= 1 µF, EN = High, T
AMB
=
25°C
Name
Quiescent Current
Shutdown Current
LED Current Accuracy
LED Channel Matching
Output Resistance (open loop)
Charge Pump Frequency
Output short circuit Current Limit
Input Current Limit
1x to 1.5x, or 1.5x to 2x
Transition Thresholds at any LED pin
1.5x to 1x Mode Transition Hysteresis
1
Transition Filter Delay
PWM1,
Input Leakage
PWM2
High
Logic Level
pins
Low
1
PWM frequency
PWM Pulse HIGH/LOW state
PWM Low Time to Shutdown
1
Thermal Shutdown
1
Thermal Hysteresis
Under Voltage Lockout (UVLO)
1
Threshold
Over Voltage Protection
1
Conditions
1x mode, no load
V
PWM
= 0V
To factory preset value
(I
LED
- I
LEDAVG
) / I
LEDAVG
1x mode
1.5x mode
2x mode
1.5x mode and 2x mode
Vout < 0.5V
Vout > 1V
Min
Typ
1.7
±3
±1
0.8
5.5
6.5
1.1
35
450
75
600
800
-5
-5
Max
2.5
1
+5
+5
Units
mA
µA
%
%
Ω
MHz
mA
mA
130
mV
mV
µs
µA
V
Hz
ns
ms
°C
-1
1.3
100
200
30
150
20
2.2
1
0.4
100000
6.2
V
V
Sample test only
© 2009 IXYS Corp.
Characteristics subject to change without notice
2
Doc. No. 8865DS, Rev. N2.1
LDS8865
PIN DESCRIPTION
Pin #
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15, 16
TAB
Name
LEDC2
LEDC1
LEDB2
LEDB1
LEDA2
LEDA1
V
OUT
V
IN
C1+
C1-
C2+
C2-
PWM2
PWM1
GND
TAB
Function
LEDC2 cathode terminal
LEDC1 cathode terminal
LEDB2 cathode terminal
LEDB1 cathode terminal
LEDA2 cathode terminal
LEDA1 cathode terminal
Charge pump output connected to the LED anodes
Charge pump input, connect to battery or supply
Bucket capacitor 1 Positive terminal
Bucket capacitor 1 Negative terminal
Bucket capacitor 2 Positive terminal
Bucket capacitor 2 Negative terminal
LEDC bank PWM brightness control
LEDA and LEDB banks PWM brightness control
Ground Reference
Bottom Thermal Pad; connect to GND on the PCB
Top view: TQFN 16-lead 3 X 3 mm
PIN FUNCTION
V
IN
is the supply pin for the charge pump. A small 1
μ
F
ceramic bypass capacitor is required between the V
IN
pin and ground near the device. The operating input
voltage range is from 2.5V to 5.5V. Whenever the
input supply falls below the under-voltage threshold
(2.2 V), all the LED channels are disabled and the
device enters shutdown mode.
PWM1, PWM2
are the enable and PWM LED
brightness control logic inputs.. Guaranteed levels of
logic high and logic low are set at 1.3V and 0.4V
respectively. When any of PWM pins is taken high,
the device becomes enabled with maximum LED
current at associated bank. To place the device into
zero current mode, both PWM pins must be held low
for more than 30 ms.
V
OUT
is the charge pump output that is connected to
the LED anodes. A small 1
μ
ceramic bypass
F
capacitor is required between the V
OUT
pin and
ground near the device.
GND
is the ground reference for the charge pump.
The pin must be connected to the ground plane on
the PCB.
C1+, C1-
are connected to each side of the ceramic
bucket capacitor C1
C2+, C2-
are connected to each side of the ceramic
bucket capacitor C2
LEDA1 – LEDC2
provide the internal regulated
current source for each of the LED cathodes. These
pins enter high-impedance zero current state
whenever the device is in shutdown mode.
TAB
is the exposed pad underneath the package.
For best thermal performance, the tab should be
soldered to the PCB and connected to the ground
plane
© 2009 IXYS Corp.
Characteristics subject to change without notice
3
Doc. No. 8865DS, Rev. N2.1
LDS8865
TYPICAL CHARACTERISTICS
Vin = 3.6V, I
OUT
= 120mA (6 LEDs at 20mA), C
1
= C
2
= 0.22
μ
C
IN
= C
OUT
= 1μ T
AMB
= 25°C unless otherwise specified
F,
F,
Efficiency vs. Input Voltage
Power-Up in 1x mode
Ch1 – PWM, PWM2, Ch2 – Vout,
Ch3 – Output current (100mA/div)
Power-Up in 1.5x Mode
Power-Up in 2x Mode
Ch1 – PWM, PWM2, Ch2 – Vout,
Ch3 – Output current (100mA/div)
Ch1 – PWM, PWM2, Ch2 – Vout,
Ch3 – Output current (100mA/div)
Power-Down Delay (1x Mode)
Operating Waveforms in 1x Mode)
Ch1 – PWM, PWM2, Ch2 – Vout,
Ch3 – Output current (100mA/div)
Ch1 – Vin (AC coupled), Ch2 – Vout (AC coupled),
Ch3 – Output current (AC coupled 20mA/div)
© 2009 IXYS Corp.
Characteristics subject to change without notice
4
Doc. No. 8865DS, Rev. N2.1
LDS8865
Switching Waveforms in 1.5x Mode
Switching Waveforms in 2x Mode
Ch1 – Vin (AC coupled), Ch2 – Vout (AC coupled),
Ch3 – Output current (AC coupled 20mA/div)
Ch1 – Vin (AC coupled), Ch2 – Vout (AC coupled),
Ch3 – Output current (AC coupled 20mA/div)
Switching Waveforms at 1kHz PWM mode
Switching Waveforms at 10kHz PWM mode
Ch1 – PWM, PWM2, Ch2 – Vout,
Ch3 – Output current (100mA/div)
Ch1 – PWM, PWM2, Ch2 – Vout,
Ch3 – Output current (100mA/div)
Switching Waveforms at 50kHz PWM mode
Switching Waveforms at 100kHz PWM mode
Ch1 – PWM, PWM2, Ch2 – Vout,
Ch3 – Output current (100mA/div)
Ch1 – PWM, PWM2, Ch2 – Vout,
Ch3 – Output current (100mA/div)
© 2009 IXYS Corp.
Characteristics subject to change without notice
5
Doc. No. 8865DS, Rev. N2.1
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