L4979D L4979MD LOW DROP VOLTAGE REGULATOR 1 ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ Figure 1. Packages FEATURES OPERATING DC SUPPLY VOLTAGE RANGE 5.6V TO 31V LOW QUIESCENT CURRENT (6µA Typ. @ 25°C with Enable Low) HIGH PRECISION OUTPUT VOLTAGE (2%) LOW DROPOUT VOLTAGE LESS THAN 0.5V RESET CIRCUIT SENSING THE OUTPUT VOLTAGE DOWN TO 1V PROGRAMMABLE RESET PULSE DELAY WITH EXTERNAL CAPACITOR WATCHDOG PROGRAMMABLE WATCHDOG TIMER WITH EXTERNAL CAPACITOR THERMAL SHUTDOWN AND SHORT CIRCUIT PROTECTION AUTOMOTIVE TEMPERATURE RANGE (Tj = -40°C TO 150°C) ENABLE INPUT FOR ENABLING/DISABLING THE VOLTAGE REGULATOR OUTPUT SO-8 SO-20 Table 1. Order Codes Part Number Package L4979D SO-8 L4979MD SO-20 L4979D13TR SO-8 Tape & Reel L4979MD13TR SO-20 Tape & Reel Figure 2. Block Diagram 5V, 150 mA Vi Vs Vo Co Vcw Ctw gnd watchdog Wi Voltage reference En Res Vcr reset Ctr October 2004 Rev. 5 1/10 L4979MD L4979D Table 2. Pin Function SO8 N° SO20 N° Pin Name 1 1 En Enable input If high, regulator, watchdog and reset are operating. If low, regulator, watchdog and reset are shut down. 2 Function 4 gnd Ground reference 5,6,15,16 gnd Ground These pins are to be connected to a heat spreader electrically grounded 3 7 Res Reset output. It is pulled down when output voltage drops below Vo_th or frequency at Wi is too low. 4 10 Vcr Reset timing adjust A capacitor between Vcr pin and gnd sets the reset delay time (trd) 5 11 Vcw Watchdog timer adjust A capacitor between Vcw pin and gnd sets the time response of the watchdog monitor. 6 14 Wi Watchdog input. If the frequency at this input pin is too low, the Reset output is activated. 7 17 Vo Voltage regulator output Output capacitor >100nF is needed for regulator stability 8 20 Vs Supply voltage Supply capacitor (e.g. 200nF) is needed for regulator stability. 2, 3, 8, 9, 12, 13, 18, 19 N. C. not connected Figure 3. Pins Connection (Top view) EN 1 8 VS GND 2 7 VO RES 3 6 WI VCR 4 5 VCW SO8 SO8 EN 1 20 VS N.C. 2 19 N.C. N.C. 3 18 N.C. GND 4 17 VO GND 5 16 GND GND 6 15 GND RES 7 14 WI N.C. 8 13 N.C. N.C. 9 12 N.C. VCR 10 11 WCW SO20 D00AT457 2/10 L4979MD L4979D Table 3. Absolute Maximum Ratings Symbol Parameter Vvsdc DC supply voltage Ivsdc Input current Value Unit -0.3 to 40 V internally limited Vvo DC output voltage Ivo DC output current Vwi Watchdog input voltage -0.3 to Vvo +0.3 V Vod Open drain output voltage (RES) -0.3 to Vvo +0.3 V Iod Open drain output current (RES) Vcr Reset delay voltage -0.3 to Vvo +0.3 V Vcw Watchdog delay voltage -0.3 to Vvo +0.3 V Ven Enable input voltage -0.3 to 40 V Tj Junction temperature -40 to 150 °C ±2 kV VESD -0.3 to 6 V internally limited internally limited ESD voltage level (HBM-MIL STD 883C) Note: 1. Maximum ratings are absolute ratings; exceeding any one of these values may cause permanent damage to the integrated circuit. Table 4. Thermal DatA Symbol Rth j-amb Parameter Thermal resistance Junction to Ambient SO8 SO16+2+2 Unit 130 to 180 50 to 80 °C/W Table 5. Electrical Characteristcs (Vs = 5.6V to 31V, Tj = -40°C to +150°C unless otherwise specified) Pin Symbol Parameter Test Condition Min. Typ. Max. Unit GENERAL Vs, Vo Iq Quiescent current Vs = 13.5V, Io=150mA, enable high all I/O currents=0 1.5 3 mA Vs, Vo Iq Quiescent current Vs = 13.5V, Io = 0mA, enable high all I/O currents = 0 100 200 µA Vs, Vo Iq Quiescent current Vs = 13.5V, Io = 0mA, enable low all I/O currents = 0 6 20 µA Tw Thermal protection temperature 190 °C Tw_hy Thermal protection temperature hysteresis 150 10 °C 3/10 L4979MD L4979D Table 5: Electrical Characteristics (continued) Pin Symbol Parameter Test Condition Min. Typ. Max. Unit VOLTAGE REGULATOR Vo Vo_ref Output voltage Vs = 5.6 to 31V Io = 1 to 150mA 4.90 5.00 5.10 V Vo Ishort Output short circuit current (1) Vs = 13.5V 150 280 400 mA Vo Ilim Output current limitation (1) Vs = 13.5V 150 320 500 mA Vs, Vo Vline Line regulation voltage Vs = 5.6 to 31V Io = 1 to 150mA 25 mV Vo Vload Load regulation voltage Io = 1 to 150mA 25 mV Vs, Vo Vdp Drop voltage Io = 150mA 400 mV Vs, Vo SVR Ripple rejection (2) fr = 100 Hz Res Vres_l Reset output low voltage Rext = 5kΩ to Vo, Vo > 1V Res Ires_h Reset output high leakage current Vres = 5V Res R_p_u Internal Pull up resistance with respect to Vo Res Vo_th Reset threshold voltage Vcr Vrhth Vcr Vrlth Vcr 200 55 dB RESET 0.4 V 1 µA kΩ 12 25 50 Vs = 5.6 to 31V Io = 1 to 150mA 6% below Vo_ref 8% below Vo_ref 10% below Vo_ref Reset timing high threshold Vs = 13.5V 44% Vo_ref 47% Vo_ref 50% Vo_ref Reset timing low threshold Vs = 13.5V 10% Vo_ref 13% Vo_ref 16% Vo_ref Icr Charge current Vs = 13.5V 8 17 30 µA Vcr Idr Discharge current Vs = 13.5V 8 17 30 µA Res trr_2 Reset delay time (3) Vo = Vo_th -100mV 100 250 700 µs Res trd Reset pulse delay Vs = 13.5V, Ctr = 1nF 65 150 ms Wi Vih Input high voltage Vs = 13.5V 3.5 Wi Vil Input low voltage Vs = 13.5V Wi Vih Input hysteresis Vs = 13.5V 300 Wi Ii Pull down current Vs = 13.5V 10 20 µA Vcw Vwhth High threshold Vs = 13.5V 2.20 2.35 2.50 V Vcw Vwlth Low threshold Vs = 13.5V 0.50 0.65 0.80 V WATCHDOG 4/10 V 1.5 V mV L4979MD L4979D ELECTRICAL CHARACTERISTICS (continued) Pin Symbol Parameter Vcw Icwc Charge current Vcw Icwd Vcw Res Test Condition Min. Typ. Max. Unit Vs = 13.5V, Vcw = 0.1V 4 7.5 14 µA Discharge current Vs = 13.5V, Vcw = 2.5V 1.0 2.4 4.5 µA Twop Watchdog period Vs = 13.5V, Ctw = 47nF 25 50 90 ms twol Watchdog output low time Vs = 13.5V, Ctw = 47nF 6 10 22 ms 1 V ENABLE En Ven_l Enable input low voltage En Ven_h Enable input high voltage En Ven_hy Enable input hysteresis En I_leak Pull down current 3 En = 5V V 700 1000 1100 mV 2 10 20 µA Note: 1. see fig4 (behavior of output current versus regulated voltage Vo) 2. guaranteed by design 3. When Vo becomes lower than 4V, the reset reaction time decreases down to 2µs assuring a faster reset condition in this particular case. 2 VOLTAGE REGULATOR The voltage regulator uses a p-channel MOS transistor as a regulating element. With this structure a low dropout voltage at current up to 150mA is achieved. The output voltage is regulated up to transient input supply voltage of 40V. No functional interruption due to over-voltage pulses is generated. The high precision of the output voltage is obtained with a pre-trimmed reference voltage. A short circuit protection to GND is provided. Figure 4. Behavior of output current versus regulated voltage Vo (see a.m. Note 1) Vo Vo_ref Ishort Ilim 3 Iout RESET The reset circuit monitors the output voltage Vo. If the output voltage drops below Vo_th then Res becomes low with a delay time trr. Real trr value changes as a non-linear function of delta (Vo-th - Vo). The reset low signal is guaranteed for an output voltage Vo greater than 1V. When the output voltage becomes higher than Vo_th then Res goes high with a delay trd. This delay is obtained by 512 periods of an oscillator (see fig. 5). The oscillator period is given by: 5/10 L4979MD L4979D [ ( V rhth – V rlth ) ⋅ C tr ] [ ( V rhth – V rlth ) ⋅ C tr ] T osc = ----------------------------------------------------- + -----------------------------------------------------I cr I dr and reset pulse delay trd is given by: trd = 512 x Tosc Figure 5. Reset Time Diagram. Wi Vo V out_th < trr Vcr T osc trr Vrhth Vrlth trd = 512 T osc R es 4 WATCHDOG The watchdog input Wi monitors a connected microcontroller. If pulses are missing, the reset output Res is set to low. The pulse sequence time can be set within a wide range thorough the external capacitor Ctw. The watchdog circuit discharges the capacitor Ctw with the constant current Icwd. If the lower threshold Vwlth is reached, a watchdog reset is generated. To prevent this reset, the microcontroller must generate a positive edge during the discharge of the capacitor before the voltage has reached the threshold Vwlth. In order to calculate the minimum time Tdis during which the microcontroller must generate the positive edge, the following equation can be used: (Vwhth - Vwlth) x Ctw = Icwd x Tdis Each Wi positive edge switches the current source from discharging to charging; the same happens when the lower Vwlth threshold is reached. When the voltage reaches the upper threshold Vwhth the current switches from charging to discharging. The result is a saw tooth voltage at the watchdog timer capacitor Ctw. Figure 6. Watchdog time diagram Wi Twop Vwhth Vcw Vwlth Tdis twol Res 6/10 L4979MD L4979D Figure 7. SO-8 Mechanical Data & Package Dimensions mm inch DIM. MIN. TYP. MAX. MIN. TYP. MAX. A 1.35 1.75 0.053 0.069 A1 0.10 0.25 0.004 0.010 A2 1.10 1.65 0.043 0.065 B 0.33 0.51 0.013 0.020 C 0.19 0.25 0.007 0.010 D (1) 4.80 5.00 0.189 0.197 E 3.80 4.00 0.15 0.157 e 1.27 0.050 H 5.80 6.20 0.228 0.244 h 0.25 0.50 0.010 0.020 L 0.40 1.27 0.016 0.050 k ddd OUTLINE AND MECHANICAL DATA 0˚ (min.), 8˚ (max.) 0.10 0.004 Note: (1) Dimensions D does not include mold flash, protrusions or gate burrs. Mold flash, potrusions or gate burrs shall not exceed 0.15mm (.006inch) in total (both side). SO-8 0016023 C 7/10 L4979MD L4979D Figure 8. SO-20 Mechanical Data & Package Dimensions mm inch DIM. MIN. TYP. MAX. MIN. TYP. MAX. A 2.35 2.65 0.093 0.104 A1 0.10 0.30 0.004 0.012 B 0.33 0.51 0.013 0.200 C 0.23 0.32 0.009 0.013 D (1) 12.60 13.00 0.496 0.512 E 7.40 7.60 0.291 0.299 e 1.27 0.050 H 10.0 10.65 0.394 0.419 h 0.25 0.75 0.010 0.030 L 0.40 1.27 0.016 0.050 k ddd OUTLINE AND MECHANICAL DATA 0˚ (min.), 8˚ (max.) 0.10 0.004 (1) “D” dimension does not include mold flash, protusions or gate burrs. Mold flash, protusions or gate burrs shall not exceed 0.15mm per side. SO20 0016022 D 8/10 L4979MD L4979D Table 6. Revision History Date Revision Description of Changes June 2004 3 Changed the values of the parameter “Reset timing high/low threshold. July 2004 4 Pin Connection SO-20 changed. Changed some textes in the Features and table 2. Changed some values in the tables 3, 4 and 5. Changed some textes in the sections 2, 3 and 4. October 2004 5 Changed from Product Preview to final datasheet. 9/10 L4979MD - L4979D Information furnished is believed to be accurate and reliable. However, STMicroelectronics assumes no responsibility for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of STMicroelectronics. Specifications mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information previously supplied. STMicroelectronics products are not authorized for use as critical components in life support devices or systems without express written approval of STMicroelectronics. The ST logo is a registered trademark of STMicroelectronics. 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