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 protec-
tion
•
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 -40°C to 85°C.
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.
C1
*
0.1µF
1
SG29085/85A
2
C2
**
10µF
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
**
10µF
GROUND
12/90 Rev 1.1 2/94
Copyright
©
1994
1
11861 Western Avenue
∞
Garden Grove, CA 92841
(714) 898-8121
∞
FAX: (714) 893-2570
L
INFINITY
Microelectronics Inc.
SG29085/85A
ABSOLUTE MAXIMUM RATINGS
Note 1. Exceeding these values may destroy this part.
Input Voltage (V
IN
) Operating .............................................. 26V
Input Voltage (V
IN
) Overvoltage Transient .............. -15V to 60V
ON/OFF Switch ...................................................... -0.3V to V
IN
Storage Temperature Range (T
STG
) .................. -65°C to 150°C
Operating Junction Temperature (T
J
) ...............................150°C
THERMAL DATA
P Package:
Thermal Resistance-
Junction to Case
,
θ
JT
................ 4.0°C/W
*
Thermal Resistance-
Junction to Ambient
,
θ
JA
.............. 55°C/W
Note A. Junction Temperature Calculation: T
J
= T
A
+ (P
D
x
θ
JA
).
Note B. The above numbers for
θ
JC
are maximums for the limiting
*
=
θ
JT
(Junction to Tab)
thermal resistance of the package in a standard mount-
ing configuration. The
θ
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.
RECOMMENDED OPERATING CONDITIONS
(Notes 2 & 3)
Input Voltage (V
IN
) ...................................................... 9V to 26V
ON/OFF Threshold Voltage
Low Level, V
IL
(V
OUT
is OFF) .................................. 0.8V max.
High Level, V
IH
(V
OUT
is ON) .................................... 2.0V min.
Load Current V
OUT
(with adequate heatsinking) .... 5 to 1000mA
Maximum Line Transient (Load Dump) V
SB
≤
6V ....... 60V max.
Input Capacitor (V
IN
to GND) ................................... 0.1
µF
min.
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.
Reverse Polarity D.C. Input Voltage (V
IN
)
(V
O
≥
-0.6V, 16Ω load) ........................................... -15V max.
Reverse Polarity Transient Input Voltage (V
IN
)
(1% duty cycle, T
≤
100ms, V
O
≥
-9V, 16Ω load) ... -50V max.
Output Capacitor with ESR of 10Ω max.
(V
OUT
to GND & V
SB
to GND) ................................... 10µF min.
Operating Ambient Temperature Range - (T
A
)
SG29085/85A ................................................. -40°C to 85°C
(Unless otherwise specified, these specifications apply for the operating ambient temperature of T
A
=
25°C. 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.)
ELECTRICAL CHARACTERISTICS
Parameter
Voltage Output (V
OUT
) Section
Output Voltage
(Note 4)
Test Conditions
9V
≤
V
IN
≤
26V, I
O
≤
1000mA, -40°C
≤
T
A
≤
85°C
SG29085
SG29085A
9V
≤
V
IN
≤
16V, I
O
= 5mA
9V
≤
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
≤
9V
I
O
= 10mA, Pin 4 = 2.4V
I
O
= 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 (I
IH
)
ON/OFF Switch (I
IL
)
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
mΩ
mA
mA
mA
mA
µV
RMS
mV/1000hr
dB
V
V
A
V
V
µA
µA
12/90 Rev 1.1 2/94
Copyright
©
1994
2
11861 Western Avenue
∞
Garden Grove, CA 92841
(714) 898-8121
∞
FAX: (714) 893-2570
L
INFINITY
Microelectronics Inc.
SG29085/85A
ELECTRICAL CHARACTERISTICS
Parameter
Standby Output (V
SB
) 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
≤
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
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
Ω
1.2
3
mA
300
µV
RMS
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 V
IN
LINE NOISE,
ETC.
V
OUT
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 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 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
©
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
L
INFINITY
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 recom-
mended value for the output capacitors is 10µF, 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 -30°C. The effective capacitance is
reduced to zero in such a situation. Capacitors rated for -40°C
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 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 60µA will
suffice, resulting in a 10k external resistor for most applications
(Figure 1).
HIGH CURRENT OUTPUT
V
IN
R
D
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 compat-
ible 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
-40°C to 85°C
-40°C to 85°C
Connection Diagram
5
4
3
2
1
STANBY OUTPUT
ON/OFF SWITCH
GROUND
OUTPUT VOLTAGE (V
OUT
)
INPUT VOLTAGE (V
IN
)
GND
Note: 1. All packages are viewed from the top.
12/90 Rev 1.1 2/94
Copyright
©
1994
4
11861 Western Avenue
∞
Garden Grove, CA 92841
(714) 898-8121
∞
FAX: (714) 893-2570
L
INFINITY
Microelectronics Inc.
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