L4949

High supply voltage transients can cause a reset output signal perturbation. For supply voltages greater than 8.0 V the circuit shows a high immunity of the reset output against supply transients of more than 100 V/ms. For supply voltages less than 8.0 V supply transients of more than 0.4 V/ms can cause a reset signal perturbation. To improve the transient behavior for supply voltages less than 8.0 V a capacitor at Pin 3 can be used. A capacitor at Pin 3 (C3 3 1.0 mF) reduces also the output noise.

The L4949 is designed for supplying the microcomputer controlled systems especially in automotive applications which is a monolithic integrated 5.0 V voltage regulator with a very low dropout and additional functions such as poweron reset and input voltage sense.

The features of L4949 can be summarized as (1)operating DC Supply Voltage Range 5.0 V to 28 V; (2)transient supply voltage up to 40 V; (3)extremely low quiescent current in standby mode; (4)high precision standby output voltage 5.0 V ±1%; (5)output current capability up to 100 mA; (6)very low dropout voltage less than 0.4 V; (7)reset circuit sensing the output voltage; (8)programmable reset pulse delay with external capacitor; (9)voltage sense comparator; (10)thermal shutdown and short circuit protections.

The absolute maximum ratings of L4949 are (1)DC operating supply voltage VCC: 28V ; (2)transient supply voltage (t <1.0 s) VCC TR: 40V; (3)output current lout:  internally limited ; (4)output voltage Vout :20V; (5)sense input current ISI: ±1.0 mA ; (6)sense input voltage VSI: VCC ; (7)output voltages reset output VReset: 20V, sense output VSO:20V ; (8)output currents: reset output IReset 5.0A, sense output ISO 5.0 mA ; (9)preregulator output Voltage VZ: 7.0V ; (10)preregulator output current IZ: 5.0 mA ; (11)ESD protection at any pin: human body model: 2000V, machine model: 400V ; (12)thermal resistance, junction-to-air RJA suffix, dip-8 plastic package, case 626: 100 °C/W, suffix, so-8 plastic package, case 751 200 °C/W ; (13)maximim junction temperature TJ: 150°C ; (14)storage temperature range Tstg: -65 to +150°C(NOTE: ESD data available upon request).