Datasheet LT4356MP-1, LT4356MP-2 (Analog Devices) - 7
| Manufacturer | Analog Devices |
| Description | Surge Stopper |
| Pages / Page | 24 / 7 — PIN FUNCTIONS. AOUT (SO Package Only):. OUT:. EN:. SHDN:. FB:. SNS:. … |
| File Format / Size | PDF / 511 Kb |
| Document Language | English |
PIN FUNCTIONS. AOUT (SO Package Only):. OUT:. EN:. SHDN:. FB:. SNS:. FLT:. TMR:. GATE:. GND:. IN+ (SO Package Only):. VCC:
Model Line for this Datasheet
Text Version of Document
LT4356MP-1/LT4356MP-2
PIN FUNCTIONS AOUT (SO Package Only):
Amplifier Output. Open collector
OUT:
Output Voltage Sense Input. This pin senses the output of the auxiliary amplifier. It is capable of sinking voltage at the source of the N-channel MOSFET and sets up to 2mA from 80V. The negative input of the amplifier the fault timer current. When the OUT pin voltage reaches is internally connected to a 1.25V reference. 0.7V away from VCC, the EN pin goes high impedance.
EN:
Open-Collector Enable Output. The EN pin goes high
SHDN:
Shutdown Control Input. The LT4356 can be shut impedance when the voltage at the OUT pin is above (VCC down to a low current mode by pulling the SHDN pin – 0.7V), indicating the external MOSFET is fully on. The below 0.4V. Pull this pin above 2.1V or disconnect it and state of the pin is latched until the OUT pin voltage resets allow the internal current source to turn the part back on. at below 0.5V and goes back up above 2V. The internal The leakage current to ground at the pin should be limited NPN is capable of sinking up to 3mA of current from 80V to no more than 1µA if no pull-up device is used to turn to drive an LED or opto-coupler. the part on. The SHDN pin can be pulled up to 100V or
FB:
Voltage Regulator Feedback Input. Connect this pin below GND by 60V without damage. In shutdown, the to the center tap of the output resistive divider connected auxiliary amplifier turns off in the LT4356-1 but continues between the OUT pin and ground. During an overvoltage operating in the LT4356-2. condition, the GATE pin is servoed to maintain a 1.25V
SNS:
Current Sense Input. Connect this pin to the out- threshold at the FB pin. This pin is clamped internally to put of the current sense resistor. The current limit circuit 7V. Tie to GND to disable the OV clamp. controls the GATE pin to limit the sense voltage between
FLT:
Open-Collector Fault Output. This pin pulls low after VCC and SNS pins to 50mV. At the same time the sense the voltage at the TMR pin has reached the fault thresh- amplifier also starts a current source to charge up the old of 1.25V. It indicates the pass transistor is about to TMR pin. This pin can be pulled below GND by up to 60V, turn off because either the supply voltage has stayed at though the voltage difference with the VCC pin must be an elevated level for an extended period of time (volt- limited to less than 30V. Connect to VCC if unused. age fault) or the device is in an overcurrent condition
TMR:
Fault Timer Input. Connect a capacitor between (current fault). The internal NPN is capable of sink- this pin and ground to set the times for early warning, ing up to 3mA of current from 80V to drive an LED or fault and cooldown periods. The current charging up this opto-coupler. pin during fault conditions depends on the voltage differ-
GATE:
N-channel MOSFET Gate Drive Output. The GATE ence between the VCC and OUT pins. When VTMR reaches pin is pulled up by an internal charge pump current source 1.25V, the FLT pin pulls low to indicate the detection of a and clamped to 14V above the OUT pin. Both voltage and fault condition. If the condition persists, the pass transis- current amplifiers control the GATE pin to regulate the tor turns off when VTMR reaches the threshold of 1.35V. output voltage and limit the current through the MOSFET. As soon as the fault condition disappears, the pull-up current stops and a 2µA current starts to pull the TMR pin
GND:
Device Ground. down. When VTMR reaches the retry threshold of 0.5V, the
IN+ (SO Package Only):
Positive Input of the Auxiliary GATE pin pulls high turning back on the pass transistor. Amplifier. This amplifier can be used as a level detection A minimum of 10nF capacitor is needed to compensate comparator with external hysteresis or linear regulator the loop. A 10V rated X7R capacitor is recommended for control ing an external PNP transistor. This pin is clamped CTMR. internally to 7V. Connect to ground if unused.
VCC:
Positive Supply Voltage Input. The positive supply input ranges from 4V to 80V for normal operation. It can also be pulled below ground potential by up to 60V during a reverse battery condition, without damaging the part. The supply current is reduced to 7µA with all the func- tional blocks off. 4356mp12fc For more information www.linear.com/LT4356MP-1 7
PIN FUNCTIONS AOUT (SO Package Only):
Amplifier Output. Open collector
OUT:
Output Voltage Sense Input. This pin senses the output of the auxiliary amplifier. It is capable of sinking voltage at the source of the N-channel MOSFET and sets up to 2mA from 80V. The negative input of the amplifier the fault timer current. When the OUT pin voltage reaches is internally connected to a 1.25V reference. 0.7V away from VCC, the EN pin goes high impedance.
EN:
Open-Collector Enable Output. The EN pin goes high
SHDN:
Shutdown Control Input. The LT4356 can be shut impedance when the voltage at the OUT pin is above (VCC down to a low current mode by pulling the SHDN pin – 0.7V), indicating the external MOSFET is fully on. The below 0.4V. Pull this pin above 2.1V or disconnect it and state of the pin is latched until the OUT pin voltage resets allow the internal current source to turn the part back on. at below 0.5V and goes back up above 2V. The internal The leakage current to ground at the pin should be limited NPN is capable of sinking up to 3mA of current from 80V to no more than 1µA if no pull-up device is used to turn to drive an LED or opto-coupler. the part on. The SHDN pin can be pulled up to 100V or
FB:
Voltage Regulator Feedback Input. Connect this pin below GND by 60V without damage. In shutdown, the to the center tap of the output resistive divider connected auxiliary amplifier turns off in the LT4356-1 but continues between the OUT pin and ground. During an overvoltage operating in the LT4356-2. condition, the GATE pin is servoed to maintain a 1.25V
SNS:
Current Sense Input. Connect this pin to the out- threshold at the FB pin. This pin is clamped internally to put of the current sense resistor. The current limit circuit 7V. Tie to GND to disable the OV clamp. controls the GATE pin to limit the sense voltage between
FLT:
Open-Collector Fault Output. This pin pulls low after VCC and SNS pins to 50mV. At the same time the sense the voltage at the TMR pin has reached the fault thresh- amplifier also starts a current source to charge up the old of 1.25V. It indicates the pass transistor is about to TMR pin. This pin can be pulled below GND by up to 60V, turn off because either the supply voltage has stayed at though the voltage difference with the VCC pin must be an elevated level for an extended period of time (volt- limited to less than 30V. Connect to VCC if unused. age fault) or the device is in an overcurrent condition
TMR:
Fault Timer Input. Connect a capacitor between (current fault). The internal NPN is capable of sink- this pin and ground to set the times for early warning, ing up to 3mA of current from 80V to drive an LED or fault and cooldown periods. The current charging up this opto-coupler. pin during fault conditions depends on the voltage differ-
GATE:
N-channel MOSFET Gate Drive Output. The GATE ence between the VCC and OUT pins. When VTMR reaches pin is pulled up by an internal charge pump current source 1.25V, the FLT pin pulls low to indicate the detection of a and clamped to 14V above the OUT pin. Both voltage and fault condition. If the condition persists, the pass transis- current amplifiers control the GATE pin to regulate the tor turns off when VTMR reaches the threshold of 1.35V. output voltage and limit the current through the MOSFET. As soon as the fault condition disappears, the pull-up current stops and a 2µA current starts to pull the TMR pin
GND:
Device Ground. down. When VTMR reaches the retry threshold of 0.5V, the
IN+ (SO Package Only):
Positive Input of the Auxiliary GATE pin pulls high turning back on the pass transistor. Amplifier. This amplifier can be used as a level detection A minimum of 10nF capacitor is needed to compensate comparator with external hysteresis or linear regulator the loop. A 10V rated X7R capacitor is recommended for control ing an external PNP transistor. This pin is clamped CTMR. internally to 7V. Connect to ground if unused.
VCC:
Positive Supply Voltage Input. The positive supply input ranges from 4V to 80V for normal operation. It can also be pulled below ground potential by up to 60V during a reverse battery condition, without damaging the part. The supply current is reduced to 7µA with all the func- tional blocks off. 4356mp12fc For more information www.linear.com/LT4356MP-1 7
