Datasheet LTC3805-5 (Analog Devices) - 7
| 制造商 | Analog Devices |
| 描述 | Adjustable Frequency Current Mode Flyback/Boost/SEPIC DC/DC Controller |
| 页数 / 页 | 20 / 7 — PIN FUNCTIONS SSFLT (Pin 1):. ISENSE (Pin 7):. TH (Pin 2):. OC (Pin 8):. … |
| 文件格式/大小 | PDF / 265 Kb |
| 文件语言 | 英语 |
PIN FUNCTIONS SSFLT (Pin 1):. ISENSE (Pin 7):. TH (Pin 2):. OC (Pin 8):. FB (Pin 3):. VCC (Pin 9):. RUN (Pin 4):. GATE (Pin 10):
该数据表的模型线
文件文字版本
LTC3805-5
PIN FUNCTIONS SSFLT (Pin 1):
Soft-Start Pin. A capacitor placed from
ISENSE (Pin 7):
Performs two functions: for current mode this pin to GND (Exposed Pad) controls the rate of rise of control, it monitors the switch current, using the voltage converter output voltage during start-up. This capacitor is across an external current sense resistor. Pin 7 also injects also used for time out after a fault prior to restart. a current ramp that develops slope compensation voltage
I
across an optional external programming resistor.
TH (Pin 2):
Error Amplifier Compensation Point. Normal operating voltage range is clamped between 0.7V and
OC (Pin 8):
Overcurrent Pin. Connect this pin to the ex- 1.9V. ternal switch current sense resistor. An additional resistor
FB (Pin 3):
Receives the feedback voltage from an external programs the overcurrent trip level. resistor divider across the output.
VCC (Pin 9):
Supply Pin. A capacitor must closely decouple
RUN (Pin 4):
An external resistor divider connects this pin VCC to GND (Exposed Pad). to VIN and sets the thresholds for converter operation.
GATE (Pin 10):
Gate Drive for the External N-Channel
FS (Pin 5):
A resistor connected from this pin to ground MOSFET. This pin swings from GND to VCC. sets the frequency of operation.
GND (Exposed Pad Pin 11):
Ground. A capacitor must
SYNC (Pin 6):
Input to synchronize the oscillator to an closely decouple GND to VCC (Pin 9). The exposed pad external source. must be soldered to electrical ground on PCB for electrical contact and rated thermal performance.
BLOCK DIAGRAM
9 4 VCC RUN SOFT-START RAMP 800mV UNDERVOLTAGE REFERENCE LOCKOUT SSFLT 1 SHUTDOWN SOFT-START OVERCURRENT FAULT 10µA COMPARATOR OC 8 + 100mV – – CURRENT COMPARATOR GATE ERROR R SWITCHING + AMPLIFIER + DRIVER GATE Q LOGIC AND BLANKING 10 S CIRCUIT FB 3 – SLOPE SHUTDOWN COMP 20mV CURRENT OSCILLATOR RAMP ITH CLAMPS GND ISENSE 11 1.2V 7 ITH FS SYNC 2 5 6 38055 BD 38055fe 7 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration order information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Typical Applications Package Description Revision History Typical Application Related Parts
PIN FUNCTIONS SSFLT (Pin 1):
Soft-Start Pin. A capacitor placed from
ISENSE (Pin 7):
Performs two functions: for current mode this pin to GND (Exposed Pad) controls the rate of rise of control, it monitors the switch current, using the voltage converter output voltage during start-up. This capacitor is across an external current sense resistor. Pin 7 also injects also used for time out after a fault prior to restart. a current ramp that develops slope compensation voltage
I
across an optional external programming resistor.
TH (Pin 2):
Error Amplifier Compensation Point. Normal operating voltage range is clamped between 0.7V and
OC (Pin 8):
Overcurrent Pin. Connect this pin to the ex- 1.9V. ternal switch current sense resistor. An additional resistor
FB (Pin 3):
Receives the feedback voltage from an external programs the overcurrent trip level. resistor divider across the output.
VCC (Pin 9):
Supply Pin. A capacitor must closely decouple
RUN (Pin 4):
An external resistor divider connects this pin VCC to GND (Exposed Pad). to VIN and sets the thresholds for converter operation.
GATE (Pin 10):
Gate Drive for the External N-Channel
FS (Pin 5):
A resistor connected from this pin to ground MOSFET. This pin swings from GND to VCC. sets the frequency of operation.
GND (Exposed Pad Pin 11):
Ground. A capacitor must
SYNC (Pin 6):
Input to synchronize the oscillator to an closely decouple GND to VCC (Pin 9). The exposed pad external source. must be soldered to electrical ground on PCB for electrical contact and rated thermal performance.
BLOCK DIAGRAM
9 4 VCC RUN SOFT-START RAMP 800mV UNDERVOLTAGE REFERENCE LOCKOUT SSFLT 1 SHUTDOWN SOFT-START OVERCURRENT FAULT 10µA COMPARATOR OC 8 + 100mV – – CURRENT COMPARATOR GATE ERROR R SWITCHING + AMPLIFIER + DRIVER GATE Q LOGIC AND BLANKING 10 S CIRCUIT FB 3 – SLOPE SHUTDOWN COMP 20mV CURRENT OSCILLATOR RAMP ITH CLAMPS GND ISENSE 11 1.2V 7 ITH FS SYNC 2 5 6 38055 BD 38055fe 7 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration order information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Typical Applications Package Description Revision History Typical Application Related Parts