Datasheet LT4356-3 (Analog Devices) - 7

LT4356-3
PIN FUNCTIONS AOUT (DFN and SO Packages Only):
Amplifier Output. Open the fault timer current. When the OUT pin voltage reaches collector output of the auxiliary amplifier. It is capable of 0.7V away from VCC, the EN pin goes high impedance. sinking up to 2mA from 80V. The negative input of the
SHDN:
Shutdown Control Input. Pulling the SHDN pin amplifier is internally connected to a 1.25V reference. low shuts the LTC4356-3 down to a low current mode. All
EN:
Open-Collector Enable Output. The EN pin goes high functions, including the GATE and the spare amplifier are impedance when the voltage at the OUT pin is above (VCC turned off. The SHDN input threshold is similar to a TTL – 0.7V), indicating the external MOSFET is fully on. The input. If the SHDN voltage goes below 2.1V, the voltage state of the pin is latched until the OUT pin voltage resets must go below 0.4V for 100µs to properly shut down the at below 0.5V and goes back up above 2V. The internal part. To turn the part back on, the SHDN voltage must NPN is capable of sinking up to 3mA of current from 80V transition from below 0.4V to greater than 2.1V with a slew to drive an LED or opto-coupler. rate faster than 10V/ms. An internal 7µA current source
Exposed Pad:
Exposed pad may be left open or connected is provided to pull the SHDN pin up. An external pull-up to device ground (GND). device should be used if the leakage current to ground might exceed 1µA. After a fault time-out which turns the
FB:
Voltage Regulator Feedback Input. Connect this pin GATE off, the GATE can be restarted by shutting down and to the center tap of the output resistive divider connected restarting the part. The SHDN pin can be pulled up to 100V between the OUT pin and ground. During an overvoltage or below GND by 60V without damage. condition, the GATE pin is servoed to maintain a 1.25V threshold at the FB pin. This pin is clamped internally to
SNS:
Current Sense Input. Connect this pin to the output of 7V. Tie to GND to disable the OV clamp. the current sense resistor. The current limit circuit controls the GATE pin to limit the sense voltage between VCC and
FLT:
Open-Collector Fault Output. This pin pulls low SNS pins to 50mV. At the same time the sense amplifier after the voltage at the TMR pin has reached the fault also starts a current source to charge up the TMR pin. threshold of 1.25V. It indicates the pass transistor is This pin can be pulled below GND by up to 60V, though about to turn off because either the supply voltage has the voltage difference with the VCC pin must be limited to stayed at an elevated level for an extended period of less than 30V. Connect to VCC if unused. time (voltage fault) or the device is in an overcurrent condition (current fault). The internal NPN is capable of
TMR:
Fault Timer Input. Connect a capacitor between this sinking up to 3mA of current from 80V to drive an LED or pin and ground to set the times for early warning and fault opto-coupler. periods. The current charging up this pin during fault conditions depends on the voltage difference between the
GATE:
N-Channel MOSFET Gate Drive Output. The GATE VCC and OUT pins. When VTMR reaches 1.25V, the FLT pin pin is pulled up by an internal charge pump current source pulls low to indicate the detection of a fault condition. If and clamped to 14V above the OUT pin. Both voltage and the condition persists, the pass transistor turns off when current amplifiers control the GATE pin to regulate the VTMR reaches the threshold of 1.35V. The GATE pin remains output voltage and limit the current through the MOSFET. low even after the fault condition has disappeared and the
GND:
Device Ground. voltage at the TMR pin has reached 0.5V. A minimum of 10nF capacitor is needed to compensate the loop. A 10V
IN+ (DFN and SO Packages Only):
Positive Input of the rated X7R capacitor is recommended for CTMR. Auxiliary Amplifier. This amplifier can be used as a level detection comparator with external hysteresis or linear
VCC:
Positive Supply Voltage Input. The positive supply regulator controlling an external PNP transistor. This pin input ranges from 4V to 80V for normal operation. It is clamped internally to 7V. Connect to ground if unused. can also be pulled below ground potential by up to 60V during a reverse battery condition, without damaging the
OUT:
Output Voltage Sense Input. This pin senses the part. The supply current is reduced to 7µA with all the voltage at the source of the N-channel MOSFET and sets functional blocks off. Rev D For more information www.analog.com 7 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Typical Applications Revision History Typical Application .18702 Applications Typical Application Description 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