Datasheet LT1683 (Analog Devices) - 6

LT1683
TYPICAL PERFORMANCE CHARACTERISTICS Gate Drive Undervoltage Lockout Voltage vs Temperature Soft-Start Current vs Temperature V5 Voltage vs Load Current
7.3 9.5 5.08 7.2 GCL = 6V 9.3 SS VOLTAGE = 0.9V 5.06 7.1 9.1 T = 125°C 7.0 8.9 5.04 6.9 8.7 6.8 8.5 5.02 T = 25°C 6.7 8.3 PIN VOLTAGE (V) 5.00 V IN 6.6 SS PIN CURRENT (µA) 8.1 V5 PIN VOLTAGE (V) T = –40°C 6.5 7.9 4.98 6.4 7.7 6.3 7.5 4.96 –50 –25 0 25 50 75 100 125 150 –50 –25 0 25 50 75 100 125 150 –15 –10 –5 0 5 10 15 TEMPERATURE (°C) TEMPERATURE (°C) LOAD CURRENT (mA) 1683 G15 1683 G16 1683 G17
PIN FUNCTIONS Part Supply
shutdown function. The hysteresis voltage will be set by the
V5 (Pin 5):
This pin provides a 5V output that can sink or Thevenin resistance of the resistor divider driving this pin source 10mA for use by external components. V5 source times the current sourced out. Above approximately 2.1V current comes from V the hysteresis current is removed. There is approximately IN . Sink current goes to GND. VIN must be greater than 6.5V in order for this voltage to be 0.1V of voltage hysteresis on this pin as well. in regulation. If this pin is used, a small capacitor (<1µF) The pin can be tied high (to VIN for instance). may be placed on this pin to reduce noise. This pin can
V
be left open if not used.
IN (Pin 17):
Input Supply. All supply current for the part comes from this pin including gate drives and V5 regula-
GND (Pin 11):
Signal Ground. The internal error ampli- tor. Charge current for gate drives can produce current fier, negative feedback amplifier, oscillator, slew control pulses of hundreds of milliamperes. Bypass this pin with circuitry, V5 regulator, current sense and the bandgap a low ESR capacitor. reference are referred to this ground. Keep the connec- When V tion to this pin, the feedback divider and V IN is below 2.55V the part will go into supply C compensation undervoltage lockout where the gate drivers are driven low. network free of large ground currents. This, along with gate drive undervoltage lockout, prevents
SHDN (Pin 14):
The shutdown pin can disable the switcher. unpredictable behavior during power up. Grounding this pin will disable all internal circuitry.
PGND (Pin 20):
Power Driver Ground. This ground comes Increasing SHDN voltage will initially turn on the internal from the MOSFET gate drivers. This pin can have several bandgap regulator. This provides a precision threshold for hundred milliamperes of current on it when the external the turn on of the rest of the IC. As SHDN increases past MOSFETs are being turned off. 1.39V the internal LDO regulator turns on, enabling the control and logic circuitry.
Oscillator
24µA of current is sourced out of the pin above the turn on
SYNC (Pin 6):
The SYNC pin can be used to synchronize threshold. This can be used to provide hysteresis for the the part to an external clock. The oscillator frequency 1683fd 6 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Test Circuits Block Diagram Operation Applications Information Typical Applications Package Description Revision History Typical Application Related Parts