sg29125/125a 12/90 rev 1.1 2/94 l in f in ity microelectronics inc. copyright ? 1994 11861 western avenue garden grove, ca 92841 1 (714) 898-8121 fax: (714) 893-2570 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 protec- tion available in plastic to-220 on/off switch for high current output description the sg29125/125a is a dual 12v/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 character- istic coupled with an extremely low dropout, (.55v for output current of 10ma) makes the sg29125/125a well suited for power systems that require standby memory. the sg29125/125a 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. the sg29125 is the 12 volt, 5% version of a family of dual regulators with a standby output voltage of 5v. other high current outputs of 5 and 8.2 volts are available. also available is the sg29125a 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 -40 c to 85 c. low dropout dual regulator typical application circuit * 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. overvoltage thermal shutdown regulator bias 1.23v reference 5v standby regulator 5.6v output voltage (12v, 1000ma) standby output (5v, 50ma) input voltage on/off switch (for output voltage only) ground c1 * 0.1 m f c3 ** 10 m f c2 ** 10 m f 2 5 3 1 4 sg29125/125a
sg29125/125a 12/90 rev 1.1 2/94 l in f in ity microelectronics inc. copyright ? 1994 11861 western avenue garden grove, ca 92841 2 (714) 898-8121 fax: (714) 893-2570 absolute maximum ratings note 1. exceeding these values may destroy this part. input voltage (v in ) operating .............................................. input voltage (v in ) overvoltage transient .............. on/off switch ....................................................... 26v -15v to 60v -0.3v to v in -65 c to 150 c 150 c storage temperature range (t stg ) .................. operating junction temperature (t j ) .............................. p package: thermal resistance- junction to case , q jt ................ 4.0c/w * thermal resistance- junction to ambient , q ja .............. 55c/w thermal data note a. junction temperature calculation: t j = t a + (p d x q ja ). note b. the above numbers for q jc are maximums for the limiting thermal resistance of the package in a standard mount- ing configuration. the q ja numbers are meant to be guidelines for the thermal performance of the device/pc- board system. all of the above assume no ambient airflow. -15v max. -50v max. 10 m f min. -40 c to 85 c electrical characteristics (unless otherwise specified, these specifications apply for the operating ambient temperature of t a = 25c, v in = 14v, i o = 500ma for v out and 10ma for v sb 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.) units v v mv mv mv m w ma ma ma ma m v rms mv/1000hr db v v a v v m a m a test conditions parameter voltage output (v out ) section 13v v in 26v, i o 1000ma, -40 c t a 85 c sg29125 sg29125a 13v v in 16v, i o = 5ma 13v v in 26v, i o = 5ma 5ma i o 1000ma 500ma dc and 10ma rms , 100hz - 10khz i o 10ma, no load on standby i o = 500ma, no load on standby i o = 750ma, no load on standby i o = 220ma, i sb = 10ma, v in = v out - 200mv 10hz - 100khz f o = 120hz i o = 500ma i o =1000ma double battery v o 13v i o = 10ma, pin 4 = 2.4v i o = 10ma, pin 4 = 0.4v sg29125/125a min. max. 11.2 11.75 .0.7 1.0 26.5 60 -10 12 12 4 10 10 200 2 40 90 15 100 20 66 0.45 1.8 31 70 12.8 12.25 25 50 50 100 25 0.6 1.2 2.5 10 typ. 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 maximum line transient on/off switch (i ih ) on/off switch (i il ) recommended operating conditions (note 2 & 3) input voltage (v in ) ..................................................... on/off threshold voltage low level, v il (v out is off) .................................. high level, v ih (v out is on) .................................... load current v out (with adequate heatsinking) ..... maximum line transient (load dump) v sb 6v ....... input capacitor (v in to gnd) ................................... 13v to 26v 0.8v max. 2.0v min. 5 to 1000ma 60v max. 0.1 m f min. reverse polarity d.c. input voltage (v in ) (v o 3 -0.6v, 16 w load) ........................................... reverse polarity transient input voltage (v in ) (1% duty cycle, t 100ms, v o 3 -9v, 16 w load) ... output capacitor with esr of 1 w max. (v out to gnd & v sb to gnd) ................................... operating ambient temperature range (t a ) sg29125/125a ............................................... note 2. range over which the device is functional. note 3. during 60v load dump, v sb shall not be less than 4.75v at i out = 10ma. * = q q q q q jt (junction to tab)
sg29125/125a 12/90 rev 1.1 2/94 l in f in ity microelectronics inc. copyright ? 1994 11861 western avenue garden grove, ca 92841 3 (714) 898-8121 fax: (714) 893-2570 electrical characteristics (continued) test conditions parameter standby output (v sb ) section units 6v v in 26v, i o 50ma, -40 c t a 85 c 6v v in 26v 1ma i o 35ma 1ma i o 50ma 1ma dc and 1ma rms , 100hz - 10khz i o 10ma, v out off 10hz - 100khz f o = 120hz i o 50ma 4.75v v o 6v sg29125/125a min. max. 4.75 50 60 5.0 4 10 25 1 1.2 300 20 66 0.55 100 70 5.25 50 25 50 3 0.7 typ. v mv mv mv w ma m v rms mv/1000hr db v ma v 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 typical circuit waveform 14v 0v 2v 0.8v 5v 0v 5v input voltage pin 1 (v) on/off switch output voltage pin 2 (v) standby voltage pin 5 (v) turn on system condition load dump low v in 3.7v 3.5v 12v 12v 12v 60v 33v 4v 26v 14v 0.8v 0v 12v 12v 5.0v turn off thermal shutdown v out short circuit line noise, etc. note 4. the temperature extremes are guaranteed but not 100% production tested. application notes 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 sg29125/ 125a fills this need as the internal bandgap reference is trimmed allowing a typical output voltage tolerance of 1%. the advantages of using a low-dropout regulator such as the sg29125/125a are the need for less headroom for full regula- tion, 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 sg29125/125a series is low quiescent current in the standby mode. when the high current or primary regulator is shut off, the
sg29125/125a 12/90 rev 1.1 2/94 l in f in ity microelectronics inc. copyright ? 1994 11861 western avenue garden grove, ca 92841 4 (714) 898-8121 fax: (714) 893-2570 5-pin to-220 plastic p - package ambient temperature range sg29125p -40 c to 85 c sg29125ap -40 c to 85 c part no. package connection diagram 5 stanby output 4 on/off switch 3 ground 2 output voltage (v out ) 1 input voltage (v in ) gnd connection diagram & ordering information (see note below) application hints external capacitors to stabilize the outputs and prevent oscillation (perhaps by many volts) external capacitors are required. the minimum recom- mended 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. conse- quently, 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 electro- lytic 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 sg29125/125a 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 oscilla- tions. 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 60 m a will suffice, resulting in a 10k external resistor for most applications (figure 1). high current output standby output v in r d 10k c3 figure 1. disabling standby output to eliminate c3 sg29125/125a note: 1. all parts are viewed from the top. 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 compat- ible with all 5 volt logic families. for use with open collector logic outputs, a 100k resistor from this pin to a 5v supply, such as pin 5, is required.
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