Datasheet AD8240 (Analog Devices) - 3

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AD8240 SPECIFICATIONS
TA = operating temperature range, VPLUS = 13.5 V, unless otherwise noted.
Table 1. Parameter Conditions Min Typ Max Unit
VO 5 V Reference = 5 V 12 V VO Regulation1 at 25°C VPLUS = 13 V to 27 V −3 ±1 +3 % VO Regulation2 -40°C to 125°C VPLUS = 13 V to 27 V −6 ±2 +6 % I 3 OUT RSHUNT = 0.4 Ω 500 mA VO Rise Time IOUT = 250 mA, CM = 22 nF, CL = 47 nF 12 µs VSENSE Gain 24 VSENSE Accuracy −7 ±3 +7 % VSENSE Output Impedance 8 10 12 kΩ Base Drive 15 mA PWM Turn-On Threshold 3.5 V PWM Turn-Off Threshold 1.4 V VSENSE Latch-Off Threshold4 0 0.1 0.3 V Latch-Off Delay5 2 µs PWM Frequency Range DC 500 Hz CM 22 nF CLOAD Range CL = 47 nF −30 +30 % Operating Current6 VPLUS > 13 V 360 µA VPLUS Operating Range 9 27 V Shutdown Current PWM low 10 µA 5 V Reference Current 160 200 240 µA Operating Temperature Range −40 +125 °C 1 VO = 12/5 of the applied reference voltage ±1% typical. Minimum VPLUS voltage for regulation depends on the external transistor Vbe and the shunt voltage. 2 VO = 12/5 of the applied reference voltage ±2% typical. Minimum VPLUS voltage for regulation depends on the external transistor Vbe and the shunt voltage. 3 The maximum output current level is set by the selection of the current shunt and power transistor. 4 (VSENSE – 5 V Reference) The latch-off level is determined by the output level of the sense amplifier. When the amplifier output approaches 5 V, the output is latched off. This allows the maximum current output level to be determined by the shunt resistor value. Latch-off can be restored to on by cycling the PWM input off and back on. 5 Internal delay only. The external delay depends on the external capacitor values, LED string impedance, and wiring inductance. 6 This specifies VPLUS only—ground current includes external transistor base drive. Rev. 0 | Page 3 of 12 Document Outline FEATURES GENERAL DESCRIPTION FUNCTIONAL BLOCK DIAGRAM PRODUCT HIGHLIGHTS SPECIFICATIONS ABSOLUTE MAXIMUM RATINGS PRODUCT DESCRIPTION LINEAR REGULATOR (BLOCK A) HIGH-SIDE CURRENT-SENSE AMPLIFIER WITH OPEN LED DETECTION (B COMPARATOR WITH LATCH-OFF OVERCURRENT PROTECTION (BLOCK C) INTELLIGENT DRIVER (BLOCK D) USING/EVALUATING THE AD8240 LED DRIVER MONITOR SETUP Shunt Resistor Selection Circuit Configuration CONTROLLING THE LED LAMP USING/EVALUATING THE VSENSE OUTPUT Using/Evaluating the Short-Circuit Protection Feature ADVANTAGES OF DRIVING LED LAMPS WITH CONSTANT VOLTAGE BACKGROUND MONITORING THE LEDS DRIVING AUTOMOTIVE LEDS Constant Current Constant Voltage OUTLINE DIMENSIONS ORDERING GUIDE