LTC3210-3 LINER [Linear Technology], LTC3210-3 Datasheet - Page 11

• Manufacturer Part Number: LTC3210-3
• Manufacturer: LINER [Linear Technology]

OPERATION
From Figure 2, for 1.5x mode the available current is
given by:
For 2x mode, the available current is given by:
Notice that the advantage voltage in this case is 3.1V • 2
– 3.8V – 0.1V = 2.3V. R
nifi cant overall increase in available current is achieved.
Typical values of R
shown in Figure 3 and Figure 4.
Shutdown Current
In shutdown mode all the circuitry is turned off and the
LTC3210-2/LTC3210-3 draw a very low current from the
V
The LTC3210-2/LTC3210-3 enter shutdown mode when
both the ENM and ENC pins are brought low at 150μs (typ).
ENM and ENC have 250k internal pull down resistors to de-
fi ne the shutdown state when the drivers are in a high imped-
ance state.
BAT
I
I
OUT
OUT
supply. Furthermore, CPO is weakly connected to V
=
=
Figure 3. Typical 1.5x R
( .
(
3.8
3.6
3.4
3.2
3.0
2.8
2.6
2.4
1 5
2
V
–40
BAT
V
V
V
C2 = C3 = C4 = 2.2μF
BAT
CPO
BAT
R
R
OL
= 3V
–
= 4.2V
–15
OL
OL
–
V
CPO
V
TEMPERATURE (°C)
as a function of temperature are
CPO
OL
10
)
is higher in 2x mode but a sig-
)
35
OL
vs Temperature
60
321023 F03
85
BAT
.
Thermal Protection
The LTC3210-2/LTC3210-3 have built-in overtemperature
protection. At internal die temperatures of around 150°C
thermal shut down will occur. This will disable all of the
current sources and charge pump until the die has cooled
by about 15°C. This thermal cycling will continue until the
fault has been corrected.
Mode Switching
The LTC3210-2/LTC3210-3 will automatically switch from
1x mode to 1.5x mode and subsequently to 2x mode
whenever a dropout condition is detected at an LED pin.
Dropout occurs when a current source voltage becomes
too low for the programmed current to be supplied. The
time from drop-out detection to mode switching is typi-
cally 0.4ms.
The part is reset back to 1x mode when the part is shut
down (ENM = ENC = Low) or on the falling edge of ENC.
An internal comparator will not allow the main switches to
connect V
CPO pin has decayed to less than or equal to the voltage
at the V
BAT
BAT
4.6
4.4
4.2
4.0
3.8
3.6
3.4
3.2
Figure 4. Typical 2x R
pin.
–40
LTC3210-2/LTC3210-3
and CPO in 1x mode until the voltage at the
V
V
C2 = C3 = C4 = 2.2μF
BAT
CPO
= 3V
= 4.8V
–15
TEMPERATURE (°C)
10
OL
35
vs Temperature
60
321023 F04
85
11
321023fa