Datasheet LT1970 (Analog Devices) - 9

LT1970
pin FuncTions VCSNK (Pin 12):
Sink Current Limit Control Voltage In- current limit is not active. ISRC, ISNK and TSD may be put. The current sink limit amplifier will activate when wired “OR” together if desired. ISRC may be left open if the sense voltage between SENSE+ and SENSE– equals this function is not monitored. –1.0 • VVCSNK/10. VCSNK may be set between VCOMMON
ISNK (Pin 17):
Sinking Current Limit Digital Output Flag. and VCOMMON + 6V. The transfer function between VCSNK ISNK is an open collector digital output. ISNK pulls low and VSENSE is linear except for very small input voltages whenever the sinking current limit amplifier assumes at VCSNK < 60mV. VSENSE limits at a minimum set point of control of the output. This pin can sink up to 10mA of 4mV typical to insure that the sink and source limit ampli- current. The current limit flag is off when the source fiers do not try to operate simultaneously. To force zero current limit is not active. ISRC, ISNK and TSD may be output current, the ENABLE pin can be taken low. wired “OR” together if desired. ISNK may be left open if
VCSRC (Pin 13):
Source Current Limit Control Voltage this function is not monitored. Input. The current source limit amplifier will activate when
TSD (Pin 18):
Thermal Shutdown Digital Output Flag. TSD the sense voltage between SENSE+ and SENSE– equals is an open collector digital output. TSD pulls low whenever VVCSRC/10. VCSRC may be set between VCOMMON and the internal thermal shutdown circuit activates, typically at VCOMMON + 6V. The transfer function between VCSRC a die temperature of 160°C. This pin can sink up to 10mA and VSENSE is linear except for very small input voltages of output current. The TSD flag is off when the die tem- at VCSRC < 60mV. VSENSE limits at a minimum set point perature is within normal operating temperatures. ISRC, of 4mV typical to insure that the sink and source limit ISNK and TSD may be wired “OR” together if desired. TSD amplifiers do not try to operate simultaneously. To force may be left open if this function is not monitored. Thermal zero output current, the ENABLE pin can be taken low. shutdown activation should prompt the user to evaluate
COMMON (Pin 14):
Control and ENABLE inputs and flag electrical loading or thermal environmental conditions. outputs are referenced to the COMMON pin. COMMON may
V+ (Pin 19):
Output Stage Positive Supply. V+ may equal be at any potential between VEE and VCC – 3V. In typical V applications, COMMON is connected to ground. CC or may be smaller in magnitude. Only output stage current flows through V+, all other current flows into VCC.
ENABLE (Pin 15):
ENABLE Digital Input Control. When V+ may be used to drive the base/gate of an external power taken low this TTL-level digital input turns off the ampli- device to boost the amplifier’s output current to levels above fier output and drops supply current to less than 1mA. the rated 500mA of the on-chip output devices. Unless Use the ENABLE pin to force zero output current. Setting used to drive boost transistors, V+ should be decoupled VCSNK = VCSRC = 0V allows IOUT = ±4mV/RSENSE to flow to ground with a low ESR capacitor. in or out of VOUT.
Package Base:
The exposed backside of the package is
ISRC (Pin 16):
Sourcing Current Limit Digital Output Flag. electrically connected to the VEE pins on the IC die. The ISRC is an open collector digital output. ISRC pulls low package base should be soldered to a heat spreading pad whenever the sourcing current limit amplifier assumes on the PC board that is electrically connected to VEE. control of the output. This pin can sink up to 10mA of current. The current limit flag is off when the source 1970fe For more information www.linear.com/LT1970 9 Document Outline Description Typical Application Absolute Maximum Ratings Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Applications Information Package Description Related Parts