LT3003EMSE-TRPBF 查看數據表（PDF） - Linear Technology
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LT3003EMSE-TRPBF Datasheet PDF : 16 Pages
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LT3003
APPLICATIONS INFORMATION
VIN
L1
D1
C1
C2
RSENSE
+
SW
EA
DRV
LED DRIVER
PWM
D1A D2A D3A
D1B D2B D3B
D1C D2C D3C
LED1
PWM
SHDN
VIN
LED2 LED3 VMAX
LT3003
VEE GND
OT1
OT2
3003 F03
VIN
C1
Figure 3. Boost Mode
RSENSE
D1A D2A D3A
D1B D2B D3B
D1C D2C D3C
LED1
PWM
LED2 LED3
LT3003
VEE
VIN VMAX
OT1
OT2
SHDN
GND
PWM
L1
+
SW
EA
DRV
LED DRIVER
C2
D1
3003 F04
Figure 4. Buck Mode
uses novel circuit techniques to reduce VEE and VMAX pin
currents to nano amp range ~10µs after PWM low edge.
This preserves the output capacitor voltage and results
in higher PWM dimming ratios.
Buck-Boost Mode: PWM Dimming
The LT3003 can also perform PWM dimming in buck-boost
mode. The buck-boost configuration requires the PWM
and SHDN pins to be tied together. This configuration can
support up to a 2000:1 PWM dimming ratio.
OT1 OT2 VIN VMAX
GND
LED3
LT3003
VEE
LED2
LED1
SHDN PWM
D3C D3B D3A
D2C D2B D2A
D1C D1B D1A RSENSE
VIN
L1
D1
C1
PWM
+
C2
SW
EA
DRV
LED DRIVER
3003 F05
Figure 5. Buck-Boost Mode
Overtemperature Protection
The LT3003 incorporates internal junction temperature
sensing and provides two open-collector outputs, OT1 and
OT2, which become active low when junction temperature
exceeds 125°C. The active OT1 output can sink 100µA of
current and can be connected to system microprocessor.
The active low OT2 output can sink 300µA of current and
can be connected to the switching regulator’s gm error
amplifier output to defeat switching. The LT3003 has to
cool down by 6°C (119°C) for OT1 and OT2 outputs to
reset (collector outputs high).
3003fa
8
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