INPUT/OUTPUT DROP TYP. 0.4V 400mA OUTPUT CURRENT LOW QUIESCENT CURRENT REVERSE POLARITY PROTECTION OVERVOLTAGE PROTECTION 60V) FOLDBACK CURRENT LIMITING THERMAL SHUTDOWN
DESCRIPTION L4800 series devices are voltage regulators with a very low voltage drop (typically 0.4V at full rated current), output current to 400mA, low quiescent current and comprehensiveon-chip protection.These devices are protected against load dump and field decay transients ± 60V, polarity reversal and overheating. A foldback current limiter protects against load short circuits. Available 9.2V,10V and12V versions (all = 25°C) these regulators are designed for automotive, industrial and consumer applications where low consumption is particularly important. BLOCK DIAGRAM
In automotive applications the L4805 is ideal for 5V logic supplies becauseit can operateeven when the batteryvoltage falls below 6V. In battery backup and standby applications the low consumption of these devices extends battery life.
Symbol VI DC Input Voltage DC Input Reverse Voltage Transient Input Overvoltages : Load Dump 5ms < Trise < 10ms, Parameter Value Unit V
f Fall Time Constant 100ms, r Rise Time Constant = 33ms
Symbol R th j-case R th j-amb Parameter Thermal Resistance Junction-case Thermal Resistance Junction-ambient Max. 4 75 Unit °C/W
TEST AND APPLICATION CIRCUIT The output capacitor is required for stability. Though the 100 µF shown is the minimum recommended value, actual size and type may vary depending upon the application load and temperature range. Capacitor effectiveseries resistance (ESR) also factors in the IC stability. Since ESR varies from one brand to the next,some bench work may be required to determine the minimum capacitor value to use in production. Worst-case is usually determined at the minimum ambient temperature and maximum load expected. Output capacitors can be increased in size to any desired value above the minimum. One possible purpose of this would be to maintain the output voltages during brief conditions of negative input transients that might be characteristics of a particular system.
Capacitors must also be rated at all ambient temperature expected in the system. Many aluminum type electrolytics will freeze at temperatures less than 30 °C, reducing their effective capacitance to zero. To maintain regulator stability down 40 °C, capacitors rated at that temperature (such as tantalums) must be used.
Symbol VO Parameter Output Voltage T est Con di tio (L4892) VI VO/VO VO Iq Operating Input Voltage Line Regulation Load Regulation Dropout Voltage Quiescent Current 400mA* VO T·VO SVR IO ISC Temperature Output Voltage Drift Supply Voltage Rejection Max Output Current Output Short Circuit Current (fold back condition) VO +3V+2Vpp Min. Typ. Max. Unit mV/V mA mV °C·V dB mA
ELECTRICAL CHARACTERISTICS (VI to 125°C (note 1) unless otherwise specified.)
Symbol VO Parameter Output Voltage T est Con di tio (L4892) VI VO/VO VO Iq Operating Input Voltage Line Regulation Load Regulation Dropout Voltage Quiescent Current see note 400mA* IO ISC Max Output Current Output Short Circuit Current (fold back condition) Min. Typ. Max. Unit mV/V V mA
Notes : 1. This limits are guaranteed by design, correlation and statistical control on production samples over the indicated temperature and supply voltage ranges.. 2. For a DC voltage < 35V the device is not operating.