LM337D2T ON Semiconductor, LM337D2T Datasheet - Page 7

• Manufacturer Part Number: LM337D2T
• Description: IC REG NEG 1.5A ADJ 4% D2PAK
• Manufacturer: ON Semiconductor

Specifications of LM337D2T

• Regulator Topology: Negative Adjustable
• Voltage - Output: -1.2 ~ -37 V
• Voltage - Input: Down to -40V
• Number Of Regulators: 1
• Current - Output: 1.5A
• Operating Temperature: 0°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: TO-263-2, D⊃2Pak (2 leads + Tab), TO-263AB
• Polarity: Negative
• Number Of Outputs: 1
• Output Type: Adjustable
• Output Voltage: - 1.2 V to - 37 V
• Output Current: 1.5 A
• Line Regulation: 0.04 % / V
• Load Regulation: 1 % / V
• Input Voltage Max: - 40 V
• Maximum Operating Temperature: + 125 C
• Minimum Operating Temperature: 0 C
• Mounting Style: SMD/SMT
• Reference Voltage: - 1.25 V
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Voltage - Dropout (typical): -
• Current - Limit (min): -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

Basic Circuit Operation
operation, the LM337 develops and maintains a nominal
−1.25 V reference (V
terminals. This reference voltage is converted to a
programming current (I
constant current flows through R
represents an error term in the equation, the LM337 was
designed to control I
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.
voltage differential across the circuit which is important to
performance, and operation at high voltages with respect to
ground is possible.
Load Regulation
regulation, but a few precautions are needed to obtain
maximum performance. For best performance, the
programming resistor (R
the regulator as possible to minimize line drops which
effectively appear in series with the reference, thereby
The LM337 is a 3−terminal floating regulator. In
The regulated output voltage is given by:
Since the current into the adjustment terminal (I
Since the LM337 is a floating regulator, it is only the
The LM337 is capable of providing extremely good load
V
in
Figure 17. Basic Circuit Configuration
Adjust
V out + V
LM337
ref
Adj
V
PROG
I
) between its output and adjustment
ref
ref
Adj
V
1
= −1.25 V Typical
to less than 100 mA and keep it
V
out
) should be connected as close to
ref
1 )
) by R
R 2
R 1
2
R
Figure 19. D
1
1
80
70
60
50
40
30
from ground.
R
I
PROG
) I
(see Figure 17), and this
Power Dissipation versus P.C.B. Copper Length
2
0
Adj
R 2
APPLICATIONS INFORMATION
Mounted
Vertically
Free Air
5.0
+
C
2
O
PAK Thermal Resistance and Maximum
+
−
L, LENGTH OF COPPER (mm)
V
V
http://onsemi.com
out
out
10
Adj
Minimum
Size Pad
)
LM337
R
7
15
P
qJA
D(max)
degrading regulation. The ground end of R
near the load ground to provide remote ground sensing and
improve load regulation.
External Capacitors
recommended to reduce the sensitivity to input line
impedance.
improve ripple rejection. This capacitor (C
ripple from being amplified as the output voltage is
increased. A 10 mF capacitor should improve ripple
rejection about 15 dB at 120 Hz in a 10 V application.
tantalum or 10 mF aluminum electrolytic capacitor is
required for stability.
Protection Diodes
it is sometimes necessary to add protection diodes to prevent
the capacitors from discharging through low current points
into the regulator.
protection diodes for output voltages in excess of −25 V or
high capacitance values (C
D
short circuit. Diode D
discharging through the IC during an output short circuit.
The combination of diodes D
the discharging through the IC during an input short circuit.
Figure 18. Voltage Regulator with Protection Diodes
1
−V
A 1.0 mF tantalum input bypass capacitor (C
The adjustment terminal may be bypassed to ground to
An output capacitance (C
When external capacitors are used with any IC regulator
Figure 18 shows the LM337 with the recommended
for T
prevents C
in
C
20
in
A
= +50°C
L
Î Î Î Î
Î Î Î Î
Î Î Î Î
Î Î Î Î
2.0 oz. Copper
+
V
25
O
in
L
from discharging thru the IC during an input
Adjust
R
1N4002
LM337
2
D1
30
2
3.5
3.0
2.5
2.0
1.5
1.0
protects against capacitor C
O
V
out
> 25 mF, C
O
1
) in the form of a 1.0 mF
and D
R
1
C
Adj
2
Adj
prevents C
1N4002
+
D
2
> 10 mF). Diode
2
can be returned
C
O
Adj
) prevents
+
Adj
+
−
in
V
from
V
) is
out
out
Adj