The LM337-N-MIL is an adjustable 3-terminal negative voltage regulator capable of supplying
−1.5 A or more currents over an output voltage range of −1.25 V to −37 V. It requires only two external resistors to set the output voltage and one output capacitor for frequency compensation. The circuit design has been optimized for excellent regulation and low thermal transients. Further, the LM337-N-MIL features internal current limiting, thermal shutdown and safe-area compensation, making it virtually blowout-proof against overloads.
The LM337-N-MIL is an ideal complement to the LM117 and LM317 adjustable positive regulators.
PART NUMBER | PACKAGE | BODY SIZE (NOM) |
---|---|---|
LM337-N-MIL | SOT-223 (4) | 3.50 mm × 6.50 mm |
TO (3) | 8.255 mm × 8.255 mm | |
TO-220 (3) | 10.16 mm × 14.986 mm |
DATE | REVISION | NOTES |
---|---|---|
June 2017 | * | Initial release. |
PIN | I/O | DESCRIPTION | |||
---|---|---|---|---|---|
NAME | TO-220 | TO | SOT-223 | ||
ADJ | 1 | 1 | 1 | — | Adjust pin |
VIN | 2, TAB | 3, CASE | 2, 4 | I | Input voltage pin for the regulator |
VOUT | 3 | 2 | 3 | O | Output voltage pin for the regulator |
MIN | MAX | UNIT | ||
---|---|---|---|---|
Power dissipation | Internally Limited | |||
Input-output voltage differential | –0.3 | 40 | V | |
Operating junction temperature | 0 | 125 | °C | |
Storage temperature, Tstg | –65 | 150 | °C |
VALUE | UNIT | |||
---|---|---|---|---|
V(ESD) | Electrostatic discharge | Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001(1) | ±2000 | V |
MIN | MAX | UNIT | |||
---|---|---|---|---|---|
Operating junction temperature | 0 | 125 | °C |
THERMAL METRIC(1) | LM337-N-MIL | UNIT | |||
---|---|---|---|---|---|
NDT (TO) |
DCY (SOT-223) |
NDE OR NDG (TO-220) |
|||
3 PINS | 3 PINS | 3 PINS | |||
RθJA | Junction-to-ambient thermal resistance | 140(2) | 58.3 | 22.9 | °C/W |
RθJC(top) | Junction-to-case (top) thermal resistance | 12 | 36.6 | 15.7 | °C/W |
RθJB | Junction-to-board thermal resistance | — | 7.2 | 4.1 | °C/W |
ψJT | Junction-to-top characterization parameter | — | 1.3 | 2.4 | °C/W |
ψJB | Junction-to-board characterization parameter | — | 7 | 4.1 | °C/W |
RθJC(bot) | Junction-to-case (bottom) thermal resistance | — | — | 1 | °C/W |
PARAMETER | TEST CONDITIONS | MIN | TYP | MAX | UNIT | |
---|---|---|---|---|---|---|
Line regulation | TJ = 25°C, 3 V ≤ |VIN − VOUT| ≤ 40 V(1)
IL = 10 mA |
0.01 | 0.04 | %/V | ||
Load regulation | TJ = 25°C, 10 mA ≤ IOUT ≤ IMAX | 0.3% | 1% | |||
Thermal regulation | TJ = 25°C, 10-ms Pulse | 0.003 | 0.04 | %/W | ||
Adjustment pin current | 65 | 100 | μA | |||
Adjustment pin current charge | 10 mA ≤ IL ≤ IMAX
3 V ≤ |VIN − VOUT| ≤ 40 V, TA = 25°C |
2 | 5 | μA | ||
Reference voltage | 3 V ≤ |VIN − VOUT| ≤ 40 V, (2)
10 mA ≤ IOUT ≤ IMAX, P ≤ PMAX |
TJ = 25°C (2) | −1.213 | −1.25 | −1.287 | V |
−55°C ≤ TJ ≤ 150°C | −1.2 | −1.25 | −1.3 | V | ||
Line regulation | 3 V ≤ |VIN − VOUT| ≤ 40 V, (1) | 0.02 | 0.07 | %/V | ||
Load regulation | 10 mA ≤ IOUT ≤ IMAX, (1) | 0.3% | 1.5% | |||
Temperature stability | TMIN ≤ Tj ≤ TMAX | 0.6% | ||||
Minimum load current | |VIN − VOUT| ≤ 40 V | 2.5 | 10 | mA | ||
|VIN − VOUT| ≤ 10 V | 1.5 | 6 | mA | |||
Current limit | |VIN − VOUT| ≤ 15 V | K, DCY and NDE package | 1.5 | 2.2 | 3.7 | A |
NDT package | 0.5 | 0.8 | 1.9 | A | ||
|VIN − VOUT| = 40 V, TJ = 25°C | K, DCY and NDE package | 0.15 | 0.4 | A | ||
NDT package | 0.1 | 0.17 | A | |||
RMS output noise, % of VOUT | Tj = 25°C, 10 Hz ≤ f ≤ 10 kHz | 0.003% | ||||
Ripple rejection ratio | VOUT = −10 V, f = 120 Hz | 60 | dB | |||
CADJ = 10 μF | 66 | 77 | dB | |||
Long-term stability | TJ = 125°C, 1000 Hours | 0.3% | 1% |
In operation, the LM337-N-MIL develops a nominal −1.25-V reference voltage between the output and adjustment terminal. The reference voltage is impressed across program resistor R1 (120 Ω for example) and, because the voltage is constant, a constant current then flows through the output set resistor R2, giving an output voltage calculated by Equation 1.
When power is dissipated in an IC, a temperature gradient occurs across the IC chip affecting the individual IC circuit components. With an IC regulator, this gradient can be especially severe because power dissipation is large. Thermal regulation is the effect of these temperature gradients on output voltage (in percentage output change) per Watt of power change in a specified time. Thermal regulation error is independent of electrical regulation or temperature coefficient, and occurs within 5 ms to 50 ms after a change in power dissipation. Thermal regulation depends on IC layout as well as electrical design. The thermal regulation of a voltage regulator is defined as the percentage change of VOUT, per Watt, within the first 10 ms after a step of power is applied.
When external capacitors are used with any IC regulator, it is sometimes necessary to add protection diodes to prevent the capacitors from discharging through low current points into the regulator. Most 10-μF capacitors have low enough internal series resistance to deliver 20-A spikes when shorted. Although the surge is short, there is enough energy to damage parts of the IC.
When an output capacitor is connected to a negative output regulator and the input is shorted, the output capacitor pulls current out of the output of the regulator. The current depends on the value of the capacitor, the output voltage of the regulator, and the rate at which VIN is shorted to ground.
The bypass capacitor on the adjustment terminal can discharge through a low current junction. Discharge occurs when either the input, or the output, is shorted. Figure 13 shows the placement of the protection diodes.