LT3579IUFD-1-PBF Просмотр технического описания (PDF) - Linear Technology

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производитель

LT3579IUFD-1-PBF

6A Boost/Inverting DC/DC Converter with Fault Protection

Linear Technology 

STATE DIAGRAM

SHDN < 1.33V

OR

VIN < 2.3V

CHIP OFF

• ALL SWITCHES DISABLED

• IGATE OFF

• FAULTS CLEARED

SHDN > 1.33V

AND

VIN > 2.3V

INITIALIZE

• SS PULLED LOW

FAULT1

SS < 50mV

SOFT START

• IGATE ENABLED

• SS CHARGES UP

• SWITCHER ENABLED

FAULT1

SAMPLE MODE

• Q1 & Q2 SWITCHES

FORCED ON EVERY CYCLE

FOR AT LEAST MINIMUM

ON-TIME

• IGATE FULLY ACTIVATED

WHEN SS > 500mV

FAULT1

IF |VOUT| DROPS CAUSING:

FB < 1.17V (BOOST)

OR

FB > 45mV (INVERTING)

NORMAL MODE

• NORMAL OPERATION

• CLKOUT ENABLED WHEN

SS > 1.8V

FAULT1

LT3579/LT3579-1

FAULT2

FAULT DETECTED

• SS CHARGES UP

• IGATE OFF

• FAULT PULLED LOW INTERNALLY BY LT3579

• SWITCHER DISABLED

• CLKOUT DISABLED

SS > 1.8V

AND NO FAULT1

CONDITIONS STILL DETECTED

POST FAULT DELAY

• SS SLOWLY DISCHARGES

FAULT1

SS < 50mV

LOCAL FAULT OVER

• INTERNAL FAULT PULLDOWN

RELEASED BY LT3579

• SS CONTINUES DISCHARGING

TO GND

FAULT > 1.0V

FAULT1

FAULT1 =

OVER VOLTAGE PROTECTION ON VIN (VIN > 16.2V (MIN))

OVER TEMPERATURE (TJUNCTION > 165°C (TYP))

OVER CURRENT ON SW1 (ISW1 > 3.4A (MIN))

OVER VOLTAGE PROTECTION ON SW1 (VSW1 > 42V (MIN))

OVER VOLTAGE PROTECTION ON SW1 (VSW2 > 42V (MIN))

FAULT2 = FAULT PULLED LOW EXTERNALLY (FAULT < 0.75V)

3759 SD

Figure 2. State Diagram

35791f

9

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