TS317
3-Terminal Adjustable Output Positive Voltage Regulator
TO-263
Pin assignment:
1. Adjustable
2. Output
3. Input
(Heatsink surface connected to pin 2)
Output Voltage Range From
1.25V to 37V
Output Current up to 1.5A
General Description
The TS317 is adjustable 3-terminal positive voltage regulator capable of supplying in excess of 1.5A over an output
voltage range of 1.25 V to 37 V. This voltage regulator is exceptionally easy to use and require only two external resistors
to set the output voltage. Further, it employs internal current limiting, thermal shutdown and safe area compensation,
making it essentially blow-out proof.
The TS317 is offered in 3-pin TO-220, TO-263, TO-252 and SOT-223 package.
Features
Output current up to 1.5A
* TO-220/TO-263 for 1.5A
* TO-252/SOT-223 for 500mA
Output Adjustable between 1.25 V and 37 V
Internal Thermal Overload Protection
Internal Short-Circuit Current Limiting Constant with
Temperature
Output Transistor Safe-Area Compensation
Floating Operation for High Voltage Applications
Eliminates Stocking Many Fixed Voltages
Output voltage offered in 4% tolerance
Standard Application
Vout = 1.25 V * (1 + R2 / R1 ) + Iadj
j
* R2
Since I
Adj
is controlled to less than 100
µA,
the error
associated with this term is negligible in most applications
A common ground is required between the input and the
output voltages. The input voltage must remain typically
2.0V above the output voltage even during the low point
on the Input ripple voltage.
* = Cin is required if regulator is located an appreciable
distance from power supply filter.
** = Co is not needed for stability; however, it does
improve transient response.
Ordering Information
Part No.
TS317CZ
TS317CM
TS317CP
TS317CW
-20 ~ +150
o
C
Operating Temp.
Package
TO-220
TO-263
TO-252
SOT-223
TS317
1-8
2003/12 rev. D
Absolute Maximum Rating
Input Voltage
Power Dissipation
Operating Junction Temperature Range
Storage Temperature Range
Vin
Pd
T
J
T
STG
40
Internal Limited
-20 ~ +150
-65 ~ +150
V
W
o
o
C
C
Electrical Characteristics
(V
I
-V
O
= 5.0 V, Io=500mA for TO-220/TO-263 packages, Io=200mA for TO-252/SOT-223 package;
Tj =T
LOW
to T
HIGH
see [Note 1]; Pmax per [Note 2]; unless otherwise specified.)
CHARACTERISTIC
Reference voltage (Note 4) Pd
≤
Pmax,
10mA
≤
Io
≤
Imax, 3.0 V
≤
Vi - Vo
≤
40 V
Line regulation (Note 3)
o
Ta = 25 C, 3.0 V
≤
Vi -Vo
≤
40 V
FIGURE
3
1
2
SYMBOL
Vref
REGline
REGload
MIN.
1.20
--
--
--
--
TYP.
1.25
0.01
5.0
0.1
0.03
50
0.2
MAX.
1.30
0.07
25
0.5
0.07
100
5.0
UNIT
V
%/V
Load regulation (Note 3)
o
Ta = 25 C, 10mA
≤
I
O
≤
Imax, V
O
≤
5.0
mV
%V
%Vo/W
uA
uA
V
O
≥
5.0
Thermal regulation
o
Ta = 25 C, 20 ms Pulse
Adjustment pin current
Adjustment pin current change, Pd
≤
Pmax,
10mA
≤
Io
≤
Imax, 2.5V
≤
V
I
- V
O
≤
40V
Maximum output current
Pd
≤
Pmax, (Vin-Vout)
≤15V
CZ, CM Package
CP, CW Package
Temperature stability (T
LOW
≤
Tj
≤
T
HIGH
)
Minimum load current to maintain regulation
(V
I
- V
O
= 40 V)
RMS Noise, % of V
O,
Ta =25
o
C, 10H
Z
≤
f
≤
10KH
Z
Long-term stability (Note 5), Tj = T
HIGH
o
Ta =25 C for endpoint measurements ,1000hrs
3
1.2
Iadj
∆Iadj
--
--
Imax
3
3
--
3
T
S
Imin
N
S
1.5
0.5
--
--
--
--
1
3.5
0.003
0.3
--
10
--
1.0
A
%
mA
%
%
Notes:
o
o
1. T
LOW
= -20 C, T
HIGH
= + 150 C
2. Pmax: CZ package=20W, CM package=3W, CP package=1.5W, CW package=0.8W,
3. Load and line regulation are specified at constant junction temperature. Changes in V
O
due to heating effects must
be taken into account separately. Pulse testing with low duty cycle is used.
4. Selected devices with tightened tolerance reference voltage available.
5. Since Long-Term Stability cannot be measured on each device before shipment, this specification is an engineering
estimate of average stability from lot to lot.
6. Cadj, when used, is connected between the adjustment pin and ground.
TS317
2-8
2003/12 rev. D
Application Information
Basic Circuit Operation
The TS317 is a 3-terminal floating regulator. In
operation, the TS317 develops and maintains a
nominal 1.25V reference (Vref) between its output and
adjustment terminals. This reference voltage is
converted to a programming current (Iprog.) by R
1
(see
Figure 17), and this constant current flows through R
2
to ground. The regulated output voltage is given by:
Vout = Vref ( 1 + R2 / R1 ) + Iadj * R2
Since the current from the adjustment terminal (Iadj)
represents an error term in the equation, the TS317
was designed to control Iadj to less than 100uA and
keep it constant. To do this, all quiescent operating
current is returned to the output terminal. This imposes
the requirement for a minimum load current. If the load
current is less than this minimum, the output voltage
will rise.
Since the TS317 is a floating regulator, it is only the
voltage differential across the circuit which is important
to performance, and operation at high voltages with
respect to ground is possible.
External Capacitor
A 0.1µF disc or 1µF tantalum input bypass capacitor
(Cin) is recommended to reduce the sensitivity to input
line impedance.
The adjustment terminal may be bypassed to ground to
improve ripple rejection. This capacitor (Cadj) prevents
ripple from being amplified as the output voltage is
rejection about 15dB at 120 H
Z
in a 10V application.
Although the TS317 is stable with no output
capacitance, like any feedback circuit, certain values of
external capacitance can cause excessive ringing. An
output increased. A 10uµF capacitor should improve
ripple capacitance (Co) in the form of a 1uF tantalum
or 25uF aluminum electrolytic capacitor on the output
swamps this effect and insures stability.
Protection Diode
When external capacitors are used with any I.C.
regulator it is sometimes necessary to add protection
diodes to prevent the capacitors from discharging
through low current points into the regulator.
Figure 18 shows the TS317 with the recommended
protection diodes for output voltages in excess of 25 V
or high capacitance values (Co > 25uF, Cadj > 10uF).
Diode D1 prevents Co from discharging thru the I.C.
during an input short circuit. Diode D2 protects against
capacitor C
ADJ
discharging through the I.C. during an
output short circuit. The combination of diodes D1 and
D2 prevents C
ADJ
from discharging through the I.C.
during an input short circuit.
Figure 5. basic circuit configuration
Load Regulation
The TS317 is capable of providing extremely good load
regulation, but a few precautions are needed to obtain
maximum performance. For best performance, the
programming resistor (R1) should be connected as
close to the regulator as possible to minimize line
drops which effectively appear in series with the
reference, thereby degrading regulation. The ground
end of R2 can be returned near the load ground to
provide remote ground sensing and improve load
regulation.
Figure 6. voltage regulator with
protection diode
TS317
5-8
2003/12 rev. D
Embedded System
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