Datasheet LTC3786 (Analog Devices) - 8
| Fabricante | Analog Devices |
| Descripción | Low IQ Synchronous Boost Controller |
| Páginas / Página | 34 / 8 — Charge Pump Charging Current. vs Operating Frequency. vs Switch Voltage. … |
| Formato / tamaño de archivo | PDF / 332 Kb |
| Idioma del documento | Inglés |
Charge Pump Charging Current. vs Operating Frequency. vs Switch Voltage. (MSOP/QFN). VFB (Pin 1/Pin 3):. SS (Pin 5/Pin 7):
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LTC3786 TYPICAL PERFORMANCE CHARACTERISTICS
Charge Pump Charging Current Charge Pump Charging Current vs Operating Frequency vs Switch Voltage
110 120 VBOOST = 16.5V 100 V FREQ = 0V SW = 12V –45°C 90 100 80 FREQ = INTV 25°C CC 70 80 60 130°C 60 50 40 40 30 155°C 20 20 10 CHARGE PUMP CHARGING CURRENT (µA) CHARGE PUMP CHARGING CURRENT (µA) 0 0 50 150 250 350 450 550 650 750 850 5 10 15 20 25 30 35 40 OPERATING FREQUENCY (kHz) SWITCH VOLTAGE (V) 3786 G27 3786 G28 PIN FUNCTIONS
(MSOP/QFN) VFB (Pin 1/Pin 3):
Error Amplifier Feedback Input. This
SS (Pin 5/Pin 7):
Output Soft-Start Input. A capacitor to pin receives the remotely sensed feedback voltage from ground at this pin sets the ramp rate of the output voltage an external resistive divider connected across the output. during start-up.
SENSE+ (Pin 2/Pin 4):
Positive Current Sense Comparator
PLLIN/MODE (Pin 6/Pin 8):
External Synchronization Input Input. The (+) input to the current comparator is normally to Phase Detector and Forced Continuous Mode Input. connected to the positive terminal of a current sense resis- When an external clock is applied to this pin, it will force tor. The current sense resistor is normally placed at the the controller into forced continuous mode of operation input of the boost controller in series with the inductor. and the phase-locked loop will force the rising BG signal This pin also supplies power to the current comparator. to be synchronized with the rising edge of the external
SENSE– (Pin 3/Pin 5):
Negative Current Sense Comparator clock. When not synchronizing to an external clock, this Input. The (–) input to the current comparator is normally input determines how the LTC3786 operates at light loads. connected to the negative terminal of a current sense re- Pulling this pin to ground selects Burst Mode operation. sistor connected in series with the inductor. The common An internal 100k resistor to ground also invokes Burst mode voltage range on the SENSE+ and SENSE– pins is Mode operation when the pin is floated. Tying this pin 2.5V to 38V (40V abs max). to INTVCC forces continuous inductor current operation. Tying this pin to a voltage greater than 1.2V and less than
ITH (Pin 4/Pin 6):
Current Control Threshold and Error INTVCC – 1.3V selects pulse-skipping operation. This can Amplifier Compensation Point. The voltage on this pin be done by adding a 100k resistor between the PLLIN/ sets the current trip threshold. MODE pin and INTVCC. 3786fc 8 For more information www.linear.com/LTC3786
Charge Pump Charging Current Charge Pump Charging Current vs Operating Frequency vs Switch Voltage
110 120 VBOOST = 16.5V 100 V FREQ = 0V SW = 12V –45°C 90 100 80 FREQ = INTV 25°C CC 70 80 60 130°C 60 50 40 40 30 155°C 20 20 10 CHARGE PUMP CHARGING CURRENT (µA) CHARGE PUMP CHARGING CURRENT (µA) 0 0 50 150 250 350 450 550 650 750 850 5 10 15 20 25 30 35 40 OPERATING FREQUENCY (kHz) SWITCH VOLTAGE (V) 3786 G27 3786 G28 PIN FUNCTIONS
(MSOP/QFN) VFB (Pin 1/Pin 3):
Error Amplifier Feedback Input. This
SS (Pin 5/Pin 7):
Output Soft-Start Input. A capacitor to pin receives the remotely sensed feedback voltage from ground at this pin sets the ramp rate of the output voltage an external resistive divider connected across the output. during start-up.
SENSE+ (Pin 2/Pin 4):
Positive Current Sense Comparator
PLLIN/MODE (Pin 6/Pin 8):
External Synchronization Input Input. The (+) input to the current comparator is normally to Phase Detector and Forced Continuous Mode Input. connected to the positive terminal of a current sense resis- When an external clock is applied to this pin, it will force tor. The current sense resistor is normally placed at the the controller into forced continuous mode of operation input of the boost controller in series with the inductor. and the phase-locked loop will force the rising BG signal This pin also supplies power to the current comparator. to be synchronized with the rising edge of the external
SENSE– (Pin 3/Pin 5):
Negative Current Sense Comparator clock. When not synchronizing to an external clock, this Input. The (–) input to the current comparator is normally input determines how the LTC3786 operates at light loads. connected to the negative terminal of a current sense re- Pulling this pin to ground selects Burst Mode operation. sistor connected in series with the inductor. The common An internal 100k resistor to ground also invokes Burst mode voltage range on the SENSE+ and SENSE– pins is Mode operation when the pin is floated. Tying this pin 2.5V to 38V (40V abs max). to INTVCC forces continuous inductor current operation. Tying this pin to a voltage greater than 1.2V and less than
ITH (Pin 4/Pin 6):
Current Control Threshold and Error INTVCC – 1.3V selects pulse-skipping operation. This can Amplifier Compensation Point. The voltage on this pin be done by adding a 100k resistor between the PLLIN/ sets the current trip threshold. MODE pin and INTVCC. 3786fc 8 For more information www.linear.com/LTC3786