LDS8865002-T2-250 IXYS, LDS8865002-T2-250 Datasheet - Page 6

• Manufacturer Part Number: LDS8865002-T2-250
• Description: IC LED DVR WHT/CLR BCKLGT 16WQFN
• Manufacturer: IXYS
• Series: PowerLite™r
• Type: Backlight, White LED, Color LEDr

Specifications of LDS8865002-T2-250

• Topology: Linear (LDO), PWM, Switched Capacitor (Charge Pump)
• Number Of Outputs: 6
• Internal Driver: Yes
• Type - Primary: Backlight
• Type - Secondary: White LED
• Frequency: 100kHz
• Voltage - Supply: 2.7 V ~ 5.5 V
• Mounting Type: Surface Mount
• Package / Case: 16-WQFN Exposed Pad, 16-DQFN
• Operating Temperature: -40°C ~ 85°C
• Current - Output / Channel: 32mA
• Internal Switch(s): Yes
• Efficiency: 94%
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Output: -
• Other names: LDS8865-002-T2; LDS8865-002-T2-2; LDS8865-002-T2-2; LDS8865002-T2-25; LDS8865002-T2-25-2; LDS8865002-T2-25-2; LDS8865002-T2-250-2

LDS8865
BLOCK DIAGRAM
BASIC OPERATION
At power-up, PWM1 and PWM2 pins should be logic
LOW. During power-up device performs internal
circuits reset that requires less than 10µs. To start
device either PWM1 or PWM2 pin should be set logic
HIGH 10µs after than input voltage applied. Device
starts operating at 1x mode at which the output is
approximately equal to the input supply voltage (less
any internal voltage losses). If the output voltage is
sufficient to regulate all LED currents, the device
remains in 1x operating mode.
The low dropout PowerLite™ Current regulator
(PCR) performs well at input voltages Vin up to 75mV
above LED forward voltage V
driver’s efficiency. The LDS8865 monitors voltage
drop Vd across PCR at every channel in ON state. If
this voltage falls below 75 mV (typical) at any one
channel, (channel with LED with highest forward
© 2009 IXYS Corp.
Characteristics subject to change without notice
F
significantly increasing
Figure 2. LDS8865 Functional Block Diagram
6
voltage), the Mode Control Block changes charge
pump mode to the next multiplication ratio.
Vd = V
Charge Pump Output Resistance at given mode, Iout
is sum of all LED currents, and M is a charge pump’
multiplication ratio.
If the input voltage is insufficient or falls to a level
where Vd ≤75 mV, and the regulated currents cannot
be maintained, the low dropout PowerLite™ Current
Regulator switches the charge pump into 1.5x mode
(after a fixed delay time of about 800 μ s). In 1.5x
mode,
approximately equal to 1.5 times the input supply
voltage (less any internal voltage losses).
This sequence repeats until driver enters the 2x
mode.
IN
the
x M – V
charge
F
– Rcp x Iout, where Rcp is a
pump’
Doc. No. 8865DS, Rev. N2.1
output
voltage
is