LDS8866002-T2-300/300/300 Leadis Technology, LDS8866002-T2-300/300/300 Datasheet - Page 8

• Manufacturer Part Number: LDS8866002-T2-300/300/300
• Description: LED Drivers 6Ch Chrg Pump w/1.33 Mode, PwrLite Reg
• Manufacturer: Leadis Technology

Specifications of LDS8866002-T2-300/300/300

• High Level Output Current: 180 mA
• Operating Supply Voltage: 2.7 V to 5.5 V
• Maximum Supply Current: 2.5 mA
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Package / Case: TQFN-16
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

LDS8866
6LEDs x 2/0.9), assuming that charge pump’s
efficiency alone at 2-x mode is 90% and maximum
factory preset current is 30 mA per LED.
When PWM LED current control is first enabled (at
cold start, for example), the LDS8866’s V
V
cycle through all four operating modes (if necessary)
so that V
LED current. To prevent nuisance switching of the
charge pump during this initial start-up sequence, a
0.8ms transition filter is applied at each charge-pump
mode. Depending on V
chosen, the maximum cold-start delay to regulated
LED current operation can be up to 2.4ms. (See
Timing Diagram Figure 3)
Once the LDS8866 reaches steady-state operation,
its charge pump remains in operation even when the
LED current is turned off (t
V
the voltage drop generated by charge pump’s R
and the total LED current load. The LDS8866’s
efficiency and LED current regulation are not affected
because the LEDs are off during this time.
If the PWM1/PWM2 pins are held high or low longer
than 30ms (Time to Shutdown), the LDS8866 turns
LEDs off. If PWM1/PWM2 pins are low, shutdown
mode is enabled and the supply current drops to 1 µA
or less. If PWM1/PWM2 pins are logic high, the
LDS8866 charge pump remains active with an overall
quiescent current ~ 1 mA.
Unused LED Channels
For applications with only two or four LEDs, unused
LED banks can be disabled via the appropriate PWM
pin connected to the ground.
For applications requiring 1, 3, or 5 channels, the
unused LED pins should be tied to V
4). If LED pin voltage is within 1 V of V
channel is switched off and a 250 μ A test current is
placed in the channel to sense when the channel
moves below V
© 2008 Leadis Technology
Characteristics subject to change without notice
PCR
OUT
monitors cause the LDS8866’s charge pump to
increases slightly by an amount proportional to
Figure 4. Application circuit with 5 LEDs
OUT
is high enough to maintain regulated
OUT
– 1.5 V.
IN
OFF
and the V
). As shown in Figure 3,
OUT
F
of the LEDs
OUT
IN
(see Figure
, V
, then the
OUT
, and
OUT
8
Protection Modes
The LDS8866 has follow protection modes
1. LED short to V
If LED pin is shorted to V
becomes as short circuit, or LED pin voltage is within
from V
recognizes this condition as “LED Short” and disables
this channel. If LED pin voltage is less than (Vout –
1.5V),
particular channel to programmed value.
2. V
The charge pump’ output voltage V
limits at about 6.2 V maximum. This is to prevent the
output pin from exceeding its absolute maximum
rating.
3. V
If V
enabled, input current may increase up to 200 – 300
mA within 20 µs after enable and is limited to 35 – 40
mA after that.
4. Over-Temperature Protection
If the die temperature exceeds +150°C, the driver will
enter shutdown mode. The LDS8866 requires restart
after die temperature falls below 130°C.
5. Input Voltage Under-Voltage Lockout
If V
enters shutdown mode. Device requires restart when
input voltage rises above 2.3 V.
6. Low V
If, in 2-x mode, V
LED current for given LED V
open circuit, or if any LED at active channels is
disconnected,
changing modes (2-x – 1-x – 1.33-x -1.5-x – 2-x -…)
in an attempt to compensate insufficient voltage. As a
result, average current at all other channels that are
ON may fall below regulated level.
LED Selection
LEDs with forward voltages (V
3.6 V may be used. Charge pumps operate in highest
efficiency when V
multiplied by switching mode, i.e. V
and so on. If the power source is a Li-ion battery,
LEDs with VF = 2.7 V - 3.3 V are recommended to
achieve highest efficiency performance and extended
operation on a single battery charge.
OUT
OUT
OUT
IN
falls below 2.2 V (typical value), LDS8866
Over-Voltage Protection
Short Circuit Protection
OUT
LDS8866 restores LED current at this
is shorted to ground before LDS8866 is
IN
or High LED V
to (V
LDS8866
OUT
IN
F
OUT
is too low to maintain regulated
voltage is close to V
protection
-
F
Voltage Detection
1.5V) range, LDS8866
F
F
Doc. No. 8866DS, Rev. 2.0
OUT
, or LED becomes an
starts
) ranging from 1.6 V to
, LED burned out
IN
OUT
x 1, V
automatically
subsequently
IN
IN
voltage
x 1.33,