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LM337IMP/NOPB

1.5A adj negative regulator, -1.2V to -37V, SOT-223, complement to LM317

6700

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Pieza del fabricante：

LM337IMP/NOPB

Paquete：

SOT-223 (6.5 x 3.5 x 1.8mm, 3-pin with tab)

Marca：

Categorías de productos：

Circuitos integrados IC, Reguladores de baja caída (LDO)

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Descripción

Productos

The LM337IMP/NOPB is a 1.5A adjustable negative voltage regulator from Texas Instruments with -1.2V to -37V output, 0.1%/V line regulation, and thermal shutdown in a SOT-223 surface-mount package.

Especificaciones

Output Voltage	-1.2V to -37V (adjustable)
Corriente de salida	1.5A (with adequate heatsinking)
Input-Output Differential	-3V to -40V (max \|VIN-VOUT\|)
Line Regulation	0.01%/V typical
Load Regulation	0.1% typical
Ripple Rejection	77dB typical
Adjustment Pin Current	50µA typical
Temperature Stability	0.0004%/°C typical
Thermal Shutdown	Yes (internally current-limited)
Temperatura de funcionamiento	0°C to +125°C (junction)
Paquete	SOT-223 (3-pin surface-mount)

Características

Adjustable negative output from -1.2V to -37V
1.5A output current with internal current limiting
Excellent line and load regulation (0.01%/V, 0.1%)
77dB ripple rejection at 120Hz
Internal thermal shutdown and safe-area compensation
Only 2 external resistors needed to set output voltage
Complement to LM317 positive regulator
SOT-223 surface-mount package for compact designs

Aplicaciones

Negative supply rails for op-amps
Dual-tracking regulators (with LM317)
Analog and instrumentation power supplies
Audio amplifier split supplies
Battery charger negative rails

Introducción del producto:LM337IMP/NOPB Presentación del producto

The LM337IMP/NOPB is the negative-output complement to the LM317, providing an adjustable negative voltage from -1.2V to -37V at up to 1.5A. The output voltage is set by two external resistors: one from the output to the ADJ pin and one from the ADJ pin to ground. The device features excellent line regulation (0.01%/V), load regulation (0.1%), and 77dB ripple rejection at 120Hz. Internal protection includes current limiting, thermal shutdown, and safe-area compensation for the pass transistor. The SOT-223 package provides surface-mount capability with adequate power dissipation for moderate input-output differentials. The IMP suffix denotes the SOT-223 package, and the NOPB suffix indicates lead-free RoHS compliance.

Principio de funcionamiento:LM337IMP/NOPB Principio de funcionamiento

The LM337IMP/NOPB uses a floating design where the ADJ pin is the reference point rather than ground. The internal bandgap reference maintains 1.25V between the output (VOUT) and ADJ pins. This reference voltage drives a constant current through the external resistor R1 (VOUT to ADJ), and the ADJ pin current (typically 50µA) flows through the second resistor R2 (ADJ to ground). The output voltage is VOUT = -1.25 × (1 + R2/R1) – 50µA × R2. Since the 50µA adjustment pin current is small and stable, the output voltage is primarily determined by the resistor ratio. The error amplifier compares the VOUT-ADJ voltage with the 1.25V reference and drives the series pass transistor to maintain regulation. The current-limiting circuit monitors output current and reduces the drive when it exceeds approximately 2.2A. The thermal shutdown disables the pass transistor when the junction temperature exceeds approximately 170°C. Safe-area protection reduces the current limit as the input-output voltage differential increases, protecting the pass transistor from secondary breakdown.

Descripción de la clavija:LM337IMP/NOPB Definición y funciones de las clavijas

Pin	Nombre	Tipo	Descripción
1	ADJ	Adjustment	Adjustment pin sets output voltage via external resistor divider. Maintained at 1.25V above VOUT by internal reference. Connect R1 from VOUT to ADJ (typically 120Ω), and R2 from ADJ to GND. Output = -1.25V × (1 + R2/R1). Adjustment pin current is typically 65µA. For fixed output, connect ADJ to the junction of two resistors between VOUT and GND.
2	VOUT	Potencia de salida	Negative regulated output voltage from -1.25V to -37V at up to 1.5A. In SOT-223-4 package, the tab (Pin 4) is electrically connected to VOUT. Bypass with 1µF solid tantalum or 10µF electrolytic to GND for stability. Output noise is typically 0.003% of VOUT.
3	VIN	Entrada de alimentación	Negative unregulated input voltage. Must be more negative than Vout – Vdropout (typ 2.5V at 1.5A). Maximum -40V input-to-output differential. Bypass with 0.1µF ceramic to GND when supply is remote. Ensure input does not exceed 0.7V above ground to avoid forward biasing internal diodes.
4	TAB	Térmico	Thermal/heatsink tab electrically connected to VOUT (Pin 2). Solder to PCB copper pour for heat dissipation. On FR-4 with 1oz copper, thermal resistance is approximately 50°C/W. For higher current, use thermal vias to internal ground plane.

LM337IMP/NOPB uses SOT-223-4 (DCY) package. Pin 1 = ADJ, Pin 2 = VOUT, Pin 3 = VIN, Pin 4 (Tab) = VOUT. Note that ADJ is Pin 1 (leftmost) unlike the LM337T TO-220 version. The tab is connected to VOUT, NOT GND. For safe operation, add protection diodes: D1 from ADJ to VOUT and D2 from VIN to VOUT to discharge capacitors during fault conditions.

Application Scenarios:In which products and applications isLM337IMP/NOPB usado

Split Supplies: Paired with LM317 creates adjustable ± supplies for op-amp circuits with matched regulation performance
Audio Amplifiers: 77dB ripple rejection and 0.01%/V line regulation ensure clean negative rail for Class-AB output stages
Instrumentation: 0.0004%/°C temperature stability maintains precision negative reference for measurement circuits
Lab Supplies: Adjustable -1.2V to -37V output covers all common negative rail requirements
Compact Designs: SOT-223 package enables surface-mount negative regulation in space-constrained PCBs

Alternative Models:What chips are recommended as replacements for LM337IMP/NOPB

Modelo	Fabricante	Diferencia clave	Paquete	Salida
LM337T/NOPB	TI	TO-220 through-hole version for higher power dissipation with heatsink mounting	TO-220-3	-1.25V to -37V adj
LM337K STEEL/NOPB	TI	TO-3 steel can for high-reliability and military applications with superior thermal performance	TO-3	-1.25V to -37V adj
KA337MTF	onsemi	SOT-223 surface-mount equivalent with 1.5A output and internal current limiting	SOT-223-4	-1.25V to -37V adj
MC337MP	onsemi	SOT-223 equivalent with identical electrical specifications and RoHS compliance	SOT-223-4	-1.25V to -37V adj
LT337MP#PBF	ADI	Higher performance version with improved load regulation and lower noise output	DDPAK-3	-1.25V to -37V adj
LM337EMP/NOPB	TI	SOT-223-4 version for space-constrained designs with 1A output current rating	SOT-223-4	-1.25V to -37V adj

The LM337IMP/NOPB uses SOT-223-4 (DCY) package. For through-hole designs with heatsinks, use LM337T/NOPB (TO-220). All LM337 variants are pin-compatible (ADJ-OUT-IN) and require only two external resistors to set the output voltage.