L4990

L4990 STMICROELECTRONICS | Alldatasheet

Document overview

• Manufacturer or author: Provided By ALLDATASHEET.COM(FREE DATASHEET DOWNLOAD SITE)
• PDF pages: 24

Technical content

SWITCHING FREQUENCY UP TO 1MHz LOW START-UP CURRENT < 0.45mA HIGH-CURRENT OUTPUT DRIVE SUITABLE FOR POWER MOSFET (1A) FULLY LATCHED PWM LOGIC WITH DOU- BLE PULSE SUPPRESSION PROGRAMMABLE DUTY CYCLE 100% AND 50% MAXIMUM DUTY CYCLE LIMIT PROGRAMMABLE SOFT START PRIMARY OVERCURRENT FAULT DETEC- TION WITH RE-START DELAY PWM UVLO WITH HYSTERESIS IN/OUT SYNCHRONIZATION DISABLE LATCHED INTERNAL 100ns LEADING EDGE BLANK- ING OF CURRENT SENSE PACKAGE: DIP16 AND SO16W

DESCRIPTION

This primary controller I.C., developed in BCD60II technology, has been designed to implement off line or DC-DC power supply applications using a fixed frequency current mode control. Based on a standard current mode PWM control- ler this device includes some features as pro- grammable soft start, IN/OUT synchronization, disable (to be used for over voltage protection and for power management), precise maximum Duty Cycle Control, 100ns (typ) leading edge blanking on current sense, pulse by pulse current limit and overcurrent protection with soft start in- tervention. July 1999 TIMING2 -14 T Vref CLK 2.5V 1.2V BLANKING PWM FAULT SOFT-START R SQ 25V 16V/10V VREF OK DIS E/A 1V R DIS 2.5V 48151 13V PWM UVLO SGND COMP SS ISEN DIS DC RCT SYNC DC-LIM VCC VREF D98IN1002 VFB PGND OUT VC OVER CURRENT BLOCK DIAGRAM ORDERING NUMBERS: L4990/L4990A(DIP16) L4990D/L4990AD (SO16W) MULTIPOWER BCD TECHNOLOGY DIP16 SO16W

Symbol Parameter Value Unit VCC Supply Voltage (ICC < 50mA) (*) selflimit V IOUT Output Peak Pulse Current 1.5 A Analog Inputs & Outputs (6,7) -0.3 to 8 V Analog Inputs & Outputs (1,2,3,4,5,15,14 13) -0.3 to 6 V P tot Power Dissipation @ Tamb =7 0°C1 W Tj Junction Temperature, Operating Range -25 to 125 °C Tstg Storage Temperature, Operating Range -55 to 150 °C (*) maximum package power dissipation limits must be observed THERMAL DATA Symbol Parameter Value Unit R th j-amb Thermal Resistance Junction to Ambient DIP16 80 °C/W R th j-amb Thermal Resistance Junction to Ambient SO16 120 °C/W PIN FUNCTIONS N. Name Function 1 SYNC Synchronization. A synchronization pulse terminates the PWM cycle and discharges Ct

2 RCT Oscillator pin for external C t,R t components

3 DC Duty Cycle control

4 VREF 5.0V +/-1.5% reference voltage

5 VFB Error Amplifier Inverting input

6 COMP Error Amplifier Output

7 SS Soft start pin for external capacitor Css

CC Supply for internal ”Signal” circuitry 9V C Supply for Power section

10 OUT High current totem pole output

11 PGND Power ground

12 SGND Signal ground

13 ISEN Current sense

14 DIS Disable. It must never be left floating. Tie to SGND if not used. 15 DC-LIM Connecting this pin to Vref, DC is limited to 50%. If it is left floating or grounded no limitation is imposed

16 NC Not connected

7 OUT

N.C.16 D95IN197 VCC 8V C9 PIN CONNECTION L4990 - L4990A

ELECTRICAL CHARACTERISTICS (VCC = 15V; Tj= 0 to 70°C; unless otherwise specified.) Symbol Parameter Test Condition Min. Typ. Max. Unit REFERENCE SECTION VO Output Voltage T j =2 5°C; IO = 1mA 4.925 5.0 5.075 V Line Regulation V CC = 12 to 20V 2.0 15 mV Load Regulation I O = 1 to 20mA 5.0 20 mV TS Temperature Stability 0.4 mV/ °C Total Variation Line, Load, Temperature 4.875 5.0 5.125 V IOS Short Circuit Current Vref = 0V 30 150 mA Power Down/UVLO V CC = 8.5V; Isink= 0.5mA 0.2 0.5 V OSCILLATOR SECTION Initial Accuracy T j =2 5°C; RT = 4.42kΩ ; C T = 1nF; pin 15 Vref 285 300 315 kHz Accuracy R T = 4.42KΩ ;VCC = 12 to 20V; C T = 1nF; pin 15 = Vref 279 300 321 kHz Initial Accuracy T j =2 5°C; RT = 4.42KΩ ; C T = 1nF; pin 15 OPEN 280 295 310 kHz Accuracy R T = 4.42KΩ ;VCC = 12 to 20V; C T = 1nF; pin 15 OPEN 275 295 315 kHz Duty Cycle pin 3 = 0,7V, pin 15 = Vref pin 3 = 0.7V, pin 15 = OPEN Duty Cycle R T = 4.42kΩ C T = 1nF pin 3 = 3.2V, pin 15 = Vref pin 3 = 3.2V, pin 15 = OPEN Duty Cycle Accuracy pin 3 = 2.02V, pin 15 = OPEN 37 40 43 % Oscillator Ramp Peak 3.0 V Oscillator Ramp Valley 1.0 V ERROR AMPLIFIER SECTION Input Bias Current V FB to GND 0.2 1.0 µA VI Input Voltage V COMP =V FB 2.42 2.5 2.58 V G OPL Open Loop Gain V COMP = 2 to 4V 60 90 dB SVR Supply Voltage Rejection V CC = 12 to 20V 85 dB V OL Output Low Voltage I sink= 2mA, VFB = 2.7V 1.1 V VOH Output High Voltage I source= 0.5mA, VFB = 2.3V 5 6 V IO Output Source Current V COMP > 4V, VFB = 2.3V 0.5 1.3 mA Output Sink Current V COMP = 1.1V, VFB = 2.7V 2 6 mA Unit Gain Bandwidth 2 4 MHz SR Slew Rate 8 V/ µs PWM CURRENT SENSE SECTION Ib Input Bias Current I sen =0 3 1 5 µA IS Maximum Input Signal V COMP = 5V 0.92 1.0 1.08 V Delay to Output 100 ns Gain 2.85 3 3.15 V/V SOFT START I SSC SS Charge Current 14 20 26 µA ISSD SS Discharge Current VSS = 0.6V 200 µA VSSSAT SS Saturation Voltage DC = 0% 0.6 V VSSCLAMP SS Clamp Voltage 7 V LEADING EDGE BLANKING Internal Masking Time 100 ns L4990 - L4990A

The I.C. contains a standard PWM current mode control section with improved performance with respect to the UC384X family. Enhanced features include start-up bias current reduced to < 270µA (typ), improved E/A perform- ance (4MHz B/W, 1.3mA Source Current, high- slew rate) accurate 1MHz oscillator, and also re- duced propagation delays in the critical path from Current Sense to Output. ADDITIONAL FEATURES Soft Start (SS) An external capacitor is charged by an internal constant current source (20µA) to generate a SS signal which clamps the E/A output The SS pin doubles as a Fault Reset Delay func- tion as described below. Current Limit / Reset Delay An internal high-speed current limit comparator ELECTRICAL CHARACTERISTICS (continued.) Symbol Parameter Test Condition Min. Typ. Max. Unit OUTPUT SECTION V OL Output Low Voltage I O = 250mA 1.0 V VOH Output High Voltage I O = 20mA; VCC = 12V 10 10.5 V IO = 200mA; VCC = 12V 9 10 V VOUT CLAMP Output Clamp Voltage I O = 5mA; VCC = 20V 13 V Collector Leakage V CC = 20V VC = 24V 100 200 µA Fall Time C O = 1nF C O = 2.5nF 60 ns ns Rise Time C O = 1nF C O = 2.5nF 100 ns ns UVLO Saturation V CC =0 Vt oVCCON ;Isink= 10mA 1.0 V SUPPLY SECTION VCCON Startup voltage L4990 L4990A 7.8 8.4 V V VCCOFF Minimum Operating Voltage L4990 L4990A 7.6 8.2 V v Vhys Voltage After Turn-on Hysteresis L4990 L4990A 5.5 0.5 0.8 V v IS Start Up Current Before Turn-on at: VCC =V CCON - 0.5V 100 270 450 µA Iop Operating Current C T = 1nF, RT = 4.42kΩ ,CO =1nF 12 18 mA Iq Quiescent Current (After turn on), Co =0nF C T = 1nF, RT = 4.42kΩ , 7.0 10 mA ISH Shutdown Current 100 270 450 µA V Z Zener Voltage I 8 = 20mA 21 25 30 V SYNCHRONIZATION SECTION Master Operation V1 Clock Amplitude I SOURCE = 0.8mA 4 V I1 Clock Source Current Vclock = 3.5V 7 mA Slave Operation V1 Sync Pulse Low Level 1 V High Level 3.5 V I1 Sync Pulse Current VSYNC = 3.5V 0.8 mA OVER CURRENT PROTECTION Vt Fault Threshold Voltage 1.1 1.2 1.3 V DISABLE SECTION Shutdown threshold 2.4 2.5 2.6 V L4990 - L4990A

160 V15 = GND/OPEN (2)

tection (see application ideas). circuit (consider some ten mA). preventswitching noise from affecting the reference. tween this pin and COMP (pin 6). ple of compensationtechniques. Figure 22. Duty cycle control.

the current consumption is extremely low. recommended to filter high frequency noise. to avoid them inducing disturbances. BJT’s (1.6A source, 2A sink, peak). CC = 0V up to the start-up threshold. fig. 26) and the circuit is disabled. separately from signal currents return. Figure 26. Pull-Down of the output in UVLO.

parts count, low cost and inherent high efficiency. ages. Numerous benefits originate from that. implies less stress for all power components. load regulation will take advantage of that. liver keeping the output well regulated. DC adapters,so this problem is of no concern. has been set at about 150 Vac (@ Iout=2A). Figure 29. Half duty cycle option.

been used to protect against output overvoltages. Table 1. System efficiency. Table 2. System performance. Figure 30. AC-DC adaptor electric schematic

Table 3. Components List of the Fig. 30 AC-DC adaptor electric schematic. Capacitors C1 100 µF 400V, NCC-SMH or equiv.

DIM. mm inch a1 0.51 0.020 B 0.77 1.65 0.030 0.065 b 0.5 0.020 b1 0.25 0.010 D 20 0.787 E 8.5 0.335 e 2.54 0.100 e3 17.78 0.700 F 7.1 0.280 I 5.1 0.201 L 3.3 0.130 Z 1.27 0.050 OUTLINE AND MECHANICAL DATA L4990 - L4990A

DIM. mm inch A 2.35 2.65 0.093 0.104 A1 0.1 0.3 0.004 0.012 B 0.33 0.51 0.013 0.020 C 0.23 0.32 0.009 0.013 D 10.1 10.5 0.398 0.413 E 7.4 7.6 0.291 0.299 e 1.27 0.050 H 10 10.65 0.394 0.419 h 0.25 0.75 0.010 0.030 L 0.4 1.27 0.016 0.050 K0 ° (min.)8° (max.) hx 45 A eB D E H L CK 1 8 SO16 Wide OUTLINE AND MECHANICAL DATA L4990 - L4990A

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. Specification 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  1999 STMicroelectronics – Printed in Italy – All Rights Reserved STMicroelectronics GROUP OF COMPANIES Australia - Brazil - China - Finland - France - Germany - Hong Kong - India - Italy - Japan - Malaysia - Malta - Morocco - Singapore - Spain - Sweden - Switzerland - United Kingdom - U.S.A. http://www.st.com L4990 - L4990A