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SG29085/85A
LOW DROPOUT DUAL REGULATOR
DESCRIPTION
The SG29085/85A is a dual 8.2V/5V positive voltage regulator. One output is a high current (up to 1000 mA) regulator that can be turned on or off by a high impedance low current TTL compatible switch. The second or standby output remains on regardless. The on/off switch not only shuts off the high current output but actually puts the IC in a micropower mode making possible a low quiescent current. This unique characteristic coupled with an extremely low dropout, (.55V for output current of 10mA) makes the SG29085/85A well suited for power systems that require standby memory. The SG29085/85A includes other features which were originally designed for automotive applications. These include protection from reverse battery installations and double battery jumps. The high current regulator has overvoltage shutdown to protect both the internal circuitry and the load during line transients, such as load dump (60V). In addition, the high current regulator design also has built-in protection for short circuit and thermal overload. During these fault conditions of the primary regulator the standby regulator will continue to power its load.
FEATURES
* 2% Internally Trimmed Output * Two regulated outputs * Output current in excess of 1000mA * Low quiescent current standby regulator * Input-output differential less than 0.6V at 0.5A * Reverse battery protection * 60V load dump protection * -50V reverse transient protection * Short circuit protection * Internal thermal overload protection * Available in plastic TO-220 The SG29085 is the 8.2 volt, 5% version of a family of dual regulators with a standby * ON/OFF switch for high current output output voltage of 5V. Other high current outputs of 5 and 12 volts are available. Also available is the SG28085A which offers an improved output voltage tolerance of 2%. They are available in the plastic TO-220 power package and are designed to function over the automotive ambient temperature range of -40C to 85C.
TYPICAL APPLICATION CIRCUIT
INPUT VOLTAGE
* Required if regulator is located far from power supply filter. ** Required for stability. May be increased without bound. Capacitor must be rated to operate at the minimum temperature expected for the regulator system.
1
C1* 0.1F
SG29085/85A
2
C2** 10F
OUTPUT VOLTAGE (8.2V, 1000mA)
OVERVOLTAGE THERMAL SHUTDOWN
ON/OFF SWITCH (for output voltage only)
4
REGULATOR BIAS
1.23V REFERENCE
5V STANDBY REGULATOR 5.6V
5
STANDBY OUTPUT (5V, 50mA)
3
C3** 10F
GROUND
12/90 Rev 1.1 2/94
Copyright (c) 1994
1
11861 Western Avenue Garden Grove, CA 92841 (714) 898-8121 FAX: (714) 893-2570
LINFINITY
Microelectronics Inc.
SG29085/85A
ABSOLUTE MAXIMUM RATINGS
Note 1. Exceeding these values may destroy this part.
Input Voltage (VIN) Operating .............................................. 26V Input Voltage (VIN) Overvoltage Transient .............. -15V to 60V ON/OFF Switch ...................................................... -0.3V to V IN
Storage Temperature Range (TSTG) .................. -65C to 150C Operating Junction Temperature (TJ ) ...............................150C
THERMAL DATA
P Package: Thermal Resistance-Junction to Case, JT ................ 4.0C/W* Thermal Resistance-Junction to Ambient, JA .............. 55C/W
Note A. Junction Temperature Calculation: TJ = TA + (PD x JA). Note B. The above numbers for JC are maximums for the limiting
*
= JT (Junction to Tab)
thermal resistance of the package in a standard mounting configuration. The JA numbers are meant to be guidelines for the thermal performance of the device/pcboard system. All of the above assume no ambient airflow.
RECOMMENDED OPERATING CONDITIONS
(Notes 2 & 3)
Input Voltage (VIN ) ...................................................... 9V to 26V ON/OFF Threshold Voltage Low Level, VIL (VOUT is OFF) .................................. 0.8V max. High Level, VIH (VOUT is ON) .................................... 2.0V min. Load Current VOUT (with adequate heatsinking) .... 5 to 1000mA Maximum Line Transient (Load Dump) VSB 6V ....... 60V max. Input Capacitor (VIN to GND) ................................... 0.1 F min.
Note 2. Range over which the device is functional. Note 3. During 60V load dump, VSB shall not be less than 4.75V at IOUT = 10mA.
Reverse Polarity D.C. Input Voltage (VIN) (VO -0.6V, 16 load) ........................................... -15V max. Reverse Polarity Transient Input Voltage (VIN ) (1% duty cycle, T 100ms, VO -9V, 16 load) ... -50V max. Output Capacitor with ESR of 10 max. (VOUT to GND & VSBto GND) ................................... 10F min. Operating Ambient Temperature Range - (TA) SG29085/85A ................................................. -40C to 85C
ELECTRICAL CHARACTERISTICS (Unless otherwise specified, these specifications apply for the operating ambient temperature of TA = 25C. VIN = 14V, IO = 500mA for VOUT and 10mA for VSB and are for DC characteristics only. Low duty cycle pulse testing techniques are used which maintains junction and case temperatures equal to the ambient temperature.)
Parameter Voltage Output (VOUT) Section Output Voltage (Note 4) Test Conditions 9V VIN 26V, IO 1000mA, -40C TA 85C SG29085 SG29085A 9V VIN 16V, IO = 5mA 9V VIN 26V, IO = 5mA 5mA IO 1000mA 500mADC and 10mARMS , 100Hz - 10kHz IO 10mA, No Load on Standby IO = 500mA, No Load on Standby IO = 750mA, No Load on Standby IO = 220mA, ISB = 10mA, VIN = VOUT - 200mV 10Hz - 100kHz FO = 120Hz IO = 500mA IO = 1000mA Double Battery VO 9V IO = 10mA, Pin 4 = 2.4V IO = 10mA, Pin 4 = 0.4V SG29085/85A Min. Typ. Max. Units
Line Regulation Load Regulation Output Impedance Quiescent Current
Output Noise Voltage Long Term Stability Ripple Rejection Dropout Voltage Current Limit Maximum Operational Input Voltage Maximum Line Transient ON/OFF Switch (IIH) ON/OFF Switch (IIL)
8.2 8.6 8.2 8.4 4 25 10 50 10 50 200 2 40 100 90 15 25 100 20 66 0.45 0.6 0.7 1.2 1.0 1.8 2.5 26.5 31 60 70 10 -10
7.8 8.0
V V mV mV mV m mA mA mA mA VRMS mV/1000hr dB V V A V V A A
12/90 Rev 1.1 2/94
Copyright (c) 1994
2
11861 Western Avenue Garden Grove, CA 92841 (714) 898-8121 FAX: (714) 893-2570
LINFINITY
Microelectronics Inc.
SG29085/85A
ELECTRICAL CHARACTERISTICS
Parameter Standby Output (VSB ) Section Output Voltage (Note 4) Line Regulation Load Regulation Output Impedance Quiescent Current Output Noise Voltage Long Term Stability Ripple Rejection Dropout Voltage Current Limit Maximum Operational Input Voltage
(continued)
Test Conditions 6V VIN 26V, IO 50mA, -40C TA 85C 6V VIN 26V 1mA IO 35mA 1mA IO 50mA 1mADC and 1mARMS, 100Hz - 10kHz IO 10mA, VOUTOFF 10Hz - 100kHz FO = 120Hz IO 50mA 4.75V VO 6V
SG29085/85A Min. Typ. Max. 4.75
Units
50 60
5.0 5.25 V 50 4 mV 10 25 mV 25 50 mV 1 1.2 3 mA 300 VRMS 20 mV/1000hr 66 dB 0.55 0.7 V 100 mA 70 V
Note 4. The temperature extremes are guaranteed but not 100% production tested.
TYPICAL CIRCUIT WAVEFORM
60V
33V INPUT VOLTAGE PIN 1 (V) 14V 4V 0V
26V
14V
ON/OFF SWITCH
2V 0.8V
0.8V
OUTPUT VOLTAGE PIN 2 (V)
5V
8.2V
8.2V 3.5V
8.2V
8.2V
8.2V
0V
0V
STANDBY VOLTAGE PIN 5 (V)
5V 3.7V
5.0V
SYSTEM CONDITION
TURN ON
LOAD DUMP
LOW VIN
LINE NOISE, ETC.
VOUT SHORT CIRCUIT
THERMAL SHUTDOWN
TURN OFF
APPLICATION NOTES
The advantages of using a low-dropout regulator such as the SG29085/85A are the need for less "headroom" for full regulation, and the inherent reverse polarity protection provided by the PNP output device. A typical NPN regulator design requires an input to output differential of approximately two volts minimum. This is due to the 2Vbe + Vcesat of the NPN Darlington used in the output, coupled with the voltage drop across the current limit resistor. In contrast, the "PNP Regulator" uses a single series pass transistor with its single Vcesat, thus the lower input to output voltage differential or dropout voltage. In addition to a low dropout voltage, an important advantage of the SG29085/85A series is low quiescent current in the standby mode. When the high current or primary regulator is shut off, the
12/90 Rev 1.1 2/94
Copyright (c) 1994
regulator enters a micropower mode. Here all but the most essential circuitry to power the standby output is deactivated. This allows the lowest possible quiescent current (typical around 1.2mA), a vital factor when used in a battery powered system. In some applications the regulator output voltage is used not only as a power supply but also as a voltage reference for control systems. In such cases not just the temperature stability of the output is important but also the initial accuracy. The SG29085/ 85A fills this need as the internal bandgap reference is trimmed allowing a typical output voltage tolerance of 1%.
3
11861 Western Avenue Garden Grove, CA 92841 (714) 898-8121 FAX: (714) 893-2570
LINFINITY
Microelectronics Inc.
SG29085/85A
APPLICATION HINTS
EXTERNAL CAPACITORS To stabilize the outputs and prevent oscillation (perhaps by many volts) external capacitors are required. The minimum recommended value for the output capacitors is 10F, although the actual size and type will likely vary according to the particular application, e.g., operating temperature range and load. Another consideration is the effective series resistance (ESR) of the capacitor. Capacitor ESR will vary by manufacturer. Consequently, some evaluation may be required to determine the minimum value of the output capacitors. Generally worst case occurs at the maximum load and minimum ambient temperature. The size of the output capacitor can be increased to any value above the minimum. One possible advantage of this would be to maintain the output voltage during brief periods of negative input transients The output capacitors chosen should be rated for the full range of ambient temperature over which the circuit will be exposed and expected to operate. For example, many aluminum type electrolytic capacitors will freeze at -30C. The effective capacitance is reduced to zero in such a situation. Capacitors rated for -40C operation must be used in order to maintain regulator stability at that temperature. Tantalum capacitors satisfy this requirement. STANDBY OUTPUT The SG29085/85A differs from most fixed voltage regulators in that it is equipped with two regulator outputs instead of one. The additional output is intended for use in systems requiring standby memory circuits. While the high current regulator output can be controlled with the ON/OFF pin described below, the standby remains on under all conditions as long as sufficient input voltage is applied to the IC. Thus, memory and other circuits powered by this output remain unaffected by positive line transients, thermal shutdown, etc. The standby regulator circuit is designed so that the quiescent current to the IC is very low (<1.5mA) when the other regulator output is off. If the standby output is not required it can be disabled. This is accomplished by connecting a resistor from the standby output to the supply voltage, thereby also eliminating the requirement for a more expensive output capacitor to prevent unwanted oscillations. The resistor value depends upon the minimum input voltage expected for a given system. Since the standby output is shunted with an internal 5.6V zener, the current through the external resistor should be sufficient to bias internal resistors up to this point. Approximately 60A will suffice, resulting in a 10k external resistor for most applications (Figure 1). HIGH CURRENT OUTPUT
VIN
RD 10K
SG29085/85A
STANDBY OUTPUT
C3
FIGURE 1. Disabling Standby Output to Eliminate C3
The high current regulated output features fault protection against overvoltage as well as a thermal shutdown feature. If the input voltage rises above 33V (load dump), the high current output shuts down automatically. The internal circuitry is thus protected and the IC is able to survive higher voltage transients than might otherwise be expected. The thermal shutdown of the high current output effectively guards against overheating of the die since this section of the IC is the principle source of power dissipation on the chip. ON/OFF SWITCH The ON/OFF pin is a high impedance low current switch that controls the main output voltage (pin 2). This is directly compatible with all 5 volt logic families. For use with open collector logic outputs, a 100Kresistor from this pin to a 5V supply, such as Pin 5, is required.
CONNECTION DIAGRAM & ORDERING INFORMATION
Package
5-PIN TO-220 PLASTIC P - PACKAGE
(See Note Below)
Part No. SG29085P SG29085AP
Ambient Temperature Range -40C to 85C -40C to 85C
Connection Diagram
5 4 3 2 1 STANBY OUTPUT ON/OFF SWITCH GROUND OUTPUT VOLTAGE (VOUT) INPUT VOLTAGE (VIN)
GND
Note: 1. All packages are viewed from the top. 12/90 Rev 1.1 2/94
Copyright (c) 1994
4
11861 Western Avenue Garden Grove, CA 92841 (714) 898-8121 FAX: (714) 893-2570
LINFINITY
Microelectronics Inc.

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