The LM2937 is a positive voltage regulator capable of supplying up to 500 mA of load current. The use of a PNP power transistor provides a low dropout voltage characteristic. With a load current of 500 mA the minimum input to output voltage differential required for the output to remain in regulation is typically 0.5 V (1-V ensured maximum over the full operating temperature range). Special circuitry has been incorporated to minimize the quiescent current to typically only 10 mA with a full 500-mA load current when the input to output voltage differential is greater than 3 V.
The LM2937 requires an output bypass capacitor for stability. As with most low dropout regulators, the ESR of this capacitor remains a critical design parameter, but the LM2937 includes special compensation circuitry that relaxes ESR requirements. The device is stable for all ESR below 3 Ω. This allows the use of low ESR chip capacitors.
Ideally suited for automotive applications, the LM2937 will protect itself and any load circuitry from reverse battery connections, two-battery jumps, and up to 60-V/−50-V load dump transients. Familiar regulator features such as short circuit and thermal shutdown protection are also built in.
PART NUMBER | PACKAGE | BODY SIZE (NOM) |
---|---|---|
LM2937 | TO-220 (3) | 14.986 mm x 10.66 mm |
SOT (4) | 6.50 mm x 3.5 mm | |
TO-263 (3) | 10.18 mm x 8.41 mm |
Changes from E Revision (June 2013) to F Revision
PIN | I/O | DESCRIPTION | |||
---|---|---|---|---|---|
NAME | NDE | KTT | DCY | ||
INPUT | 1 | 1 | 1 | I | Unregulated voltage input |
GND | 2 | 2 | 2 | — | Ground |
OUTPUT | 3 | 3 | 3 | O | Regulated voltage output. This pin requires an output capacitor to maintain stability. See the Detailed Design Procedure section for output capacitor details. |
GND | TAB | TAB | 4 | — | Thermal and ground connection. Connect the TAB to a large copper area to remove heat from the device. The TAB is internally connected to device pin 2 (GND). Connect the TAB to GND or leave floating. Do not connect the TAB to any potential other than GND at device pin 2. |
MIN | MAX | UNIT | ||
---|---|---|---|---|
Input voltage (VIN) | Continuous | 26 | V | |
Transient (t ≤ 100 ms) | 60 | |||
Internal power dissipation(3) | Internally limited | |||
Maximum junction temperature | 150 | °C |
MIN | MAX | UNIT | |||
---|---|---|---|---|---|
Tstg | Storage temperature range | −65 | 150 | °C | |
V(ESD) | Electrostatic discharge | Human body model (HBM), per ANSI/ESDA/JEDEC JS-001, all pins(1) | –2000 | 2000 | V |
MIN | NOM | MAX | UNIT | ||
---|---|---|---|---|---|
Junction temperature (TJ) (2) | LM2937ET (NDE), LM2937ES (KTT) | −40 | 125 | °C | |
LM2937IMP (DCY) | −40 | 85 | |||
Input voltage (VIN) | VOUT + 1V | 26 | V |
THERMAL METRIC(1) | LM2937 | UNIT | |||
---|---|---|---|---|---|
NDE(2) | KTT | DCY | |||
3 PINS | 3 PINS | 4 PINS | |||
RθJA | Junction-to-ambient thermal resistance | 77.9 | 41.8 | 58.3 | °C/W |
RθJC(top) | Junction-to-case (top) thermal resistance | 35.5 | 43.5 | 39.2 | |
RθJB | Junction-to-board thermal resistance | 70.6 | 0.8 | N/A | |
ψJT | Junction-to-top characterization parameter | 13 | 23.5 | 7 | |
ψJB | Junction-to-board characterization parameter | 70.6 | 10.3 | 1.6 | |
RθJC(bot) | Junction-to-case (bottom) thermal resistance | 1 | 22.5 | 22.5 |
PARAMETER | CONDITIONS | MIN | TYP | MAX | UNIT |
---|---|---|---|---|---|
Output voltage | TA = TJ = 25°C, 5 mA ≤ IOUT ≤ IOUT(MAX) | 4.85 | 5 | 5.15 | V |
5 mA ≤ IOUT ≤ IOUT(MAX) | 4.75 | 5 | 5.25 | V | |
Line regulation | (VOUT + 2 V) ≤ VIN ≤ 26 V, IOUT = 5 mA | 15 | 50 | mV | |
Load regulation | 5 mA ≤ IOUT ≤ IOUT(MAX) | 5 | 50 | mV | |
Quiescent Current | (VOUT + 2 V) ≤ VIN ≤ 26 V, IOUT = 5 mA | 2 | 10 | mA | |
VIN = (VOUT + 5 V), IOUT = IOUT(MAX) | 10 | 20 | mA | ||
Output noise voltage | 10 Hz to 100 kHz, IOUT = 5 mA | 150 | μVrms | ||
Long-term stability | 1000 Hrs. | 20 | mV | ||
Dropout voltage | IOUT = IOUT(MAX) | 0.5 | 1 | V | |
IOUT = 50 mA | 110 | 250 | mV | ||
Short-circuit current | 0.6 | 1 | A | ||
Peak line transient voltage | tf < 100 ms, RL = 100 Ω | 60 | 75 | V | |
Maximum operational input voltage | 26 | V | |||
Reverse DC input voltage | VOUT ≥ −0.6 V, RL = 100 Ω | –15 | –30 | V | |
Reverse transient input voltage | tr < 1 ms, RL = 100 Ω | –50 | –75 | V |
PARAMETER | CONDITIONS | MIN | TYP | MAX | UNIT |
---|---|---|---|---|---|
Output voltage | TA = TJ = 25°C, 5 mA ≤ IOUT ≤ IOUT(MAX) | 7.76 | 8 | 8.24 | V |
5 mA ≤ IOUT ≤ IOUT(MAX) | 7.6 | 8 | 8.4 | V | |
Line regulation | (VOUT + 2 V) ≤ VIN ≤ 26 V, IOUT = 5 mA | 24 | 80 | mV | |
Load regulation | 5 mA ≤ IOUT ≤ IOUT(MAX) | 8 | 80 | mV | |
Quiescent Current | (VOUT + 2 V) ≤ VIN ≤ 26 V, IOUT = 5 mA | 2 | 10 | mA | |
VIN = (VOUT + 5 V), IOUT = IOUT(MAX) | 10 | 20 | mA | ||
Output noise voltage | 10 Hz to 100 kHz, IOUT = 5 mA | 240 | μVrms | ||
Long-term stability | 1000 Hrs. | 32 | mV | ||
Dropout voltage | IOUT = IOUT(MAX) | 0.5 | 1 | V | |
IOUT = 50 mA | 110 | 250 | mV | ||
Short-circuit current | 0.6 | 1 | A | ||
Peak line transient voltage | tf < 100 ms, RL = 100 Ω | 60 | 75 | V | |
Maximum operational input voltage | 26 | V | |||
Reverse DC input voltage | VOUT ≥ −0.6 V, RL = 100 Ω | –15 | –30 | V | |
Reverse transient input voltage | tr < 1 ms, RL = 100 Ω | –50 | –75 | V |
PARAMETER | CONDITIONS | MIN | TYP | MAX | UNIT |
---|---|---|---|---|---|
Output voltage | TA = TJ = 25°C, 5 mA ≤ IOUT ≤ IOUT(MAX) | 9.7 | 10 | 10.3 | V |
5 mA ≤ IOUT ≤ IOUT(MAX) | 9.5 | 10 | 10.5 | V | |
Line regulation | (VOUT + 2V) ≤ VIN ≤ 26V, IOUT = 5 mA | 30 | 100 | mV | |
Load regulation | 5 mA ≤ IOUT ≤ IOUT(MAX) | 10 | 100 | mV | |
Quiescent Current | (VOUT + 2V) ≤ VIN ≤ 26V, IOUT = 5 mA | 2 | 10 | mA | |
VIN = (VOUT + 5V), IOUT = IOUT(MAX) | 10 | 20 | mA | ||
Output noise voltage | 10 Hz to 100 kHz, IOUT = 5 mA | 300 | μVrms | ||
Long-term stability | 1000 Hrs. | 40 | mV | ||
Dropout voltage | IOUT = IOUT(MAX) | 0.5 | 1 | V | |
IOUT = 50 mA | 110 | 250 | mV | ||
Short-circuit current | 0.6 | 1 | A | ||
Peak line transient voltage | tf < 100 ms, RL = 100 Ω | 60 | 75 | V | |
Maximum operational input voltage | 26 | V | |||
Reverse DC input voltage | VOUT ≥ −0.6 V, RL = 100 Ω | –15 | –30 | V | |
Reverse transient input voltage | tr < 1 ms, RL = 100 Ω | –50 | –75 | V |
PARAMETER | CONDITIONS | MIN | TYP | MAX | UNIT |
---|---|---|---|---|---|
Output voltage | TA = TJ = 25°C, 5 mA ≤ IOUT ≤ IOUT(MAX) | 11.64 | 12 | 12.36 | V |
5 mA ≤ IOUT ≤ IOUT(MAX) | 11.4 | 12 | 12.6 | V | |
Line regulation | (VOUT + 2V) ≤ VIN ≤ 26V, IOUT = 5 mA | 36 | 120 | mV | |
Load regulation | 5 mA ≤ IOUT ≤ IOUT(MAX) | 12 | 120 | mV | |
Quiescent Current | (VOUT + 2V) ≤ VIN ≤ 26V, IOUT = 5 mA | 2 | 10 | mA | |
VIN = (VOUT + 5V), IOUT = IOUT(MAX) | 10 | 20 | mA | ||
Output noise voltage | 10 Hz to 100 kHz, IOUT = 5 mA | 360 | μVrms | ||
Long-term stability | 1000 Hrs. | 44 | mV | ||
Dropout voltage | IOUT = IOUT(MAX) | 0.5 | 1 | V | |
IOUT = 50 mA | 110 | 250 | mV | ||
Short-circuit current | 0.6 | 1 | A | ||
Peak line transient voltage | tf < 100 ms, RL = 100 Ω | 60 | 75 | V | |
Maximum operational input voltage | 26 | V | |||
Reverse DC input voltage | VOUT ≥ −0.6 V, RL = 100 Ω | –15 | –30 | V | |
Reverse transient input voltage | tr < 1 ms, RL = 100 Ω | –50 | –75 | V |
PARAMETER | CONDITIONS | MIN | TYP | MAX | UNIT |
---|---|---|---|---|---|
Output voltage | TA = TJ = 25°C, 5 mA ≤ IOUT ≤ IOUT(MAX) | 14.55 | 15 | 15.45 | V |
5 mA ≤ IOUT ≤ IOUT(MAX) | 14.25 | 15 | 15.75 | V | |
Line regulation | (VOUT + 2V) ≤ VIN ≤ 26V, IOUT = 5 mA | 45 | 150 | mV | |
Load regulation | 5 mA ≤ IOUT ≤ IOUT(MAX) | 15 | 150 | mV | |
Quiescent Current | (VOUT + 2V) ≤ VIN ≤ 26V, IOUT = 5 mA | 2 | 10 | mA | |
VIN = (VOUT + 5V), IOUT = IOUT(MAX) | 10 | 20 | mA | ||
Output noise voltage | 10 Hz to 100 kHz, IOUT = 5 mA | 450 | μVrms | ||
Long-term stability | 1000 Hrs. | 56 | mV | ||
Dropout voltage | IOUT = IOUT(MAX) | 0.5 | 1 | V | |
IOUT = 50 mA | 110 | 250 | mV | ||
Short-circuit current | 0.6 | 1 | A | ||
Peak line transient voltage | tf < 100 ms, RL = 100 Ω | 60 | 75 | V | |
Maximum operational input voltage | 26 | V | |||
Reverse DC input voltage | VOUT ≥ −0.6 V, RL = 100 Ω | –15 | –30 | V | |
Reverse transient input voltage | tr < 1 ms, RL = 100 Ω | –50 | –75 | V |
The LM2937 is a positive voltage regulator capable of supplying up to 500 mA of load current. The use of a PNP power transistor provides a low dropout voltage characteristic. With a load current of 500 mA the minimum input to output voltage differential required for the output to remain in regulation is typically 0.5 V (1 V ensured maximum over the full operating temperature range). Special circuitry has been incorporated to minimize the quiescent current to typically only 10 mA with a full 500-mA load current when the input to output voltage differential is greater than 3 V.
The Thermal Shutdown circuitry of the LM2937 has been designed to protect the device against temporary thermal overload conditions. The TSD circuitry is not intended to replace proper heat-sinking. Continuously running the LM2937 device at thermal shutdown may degrade device reliability as the junction temperature will be exceeding the absolute maximum junction temperature rating.
The output current limiting circuitry of the LM2937 has been designed to limit the output current in cases where the load impedance is unusually low. This includes situations where the output may be shorted directly to ground. Continuous operation of the LM2937 at the current limit will typically result in the LM2937 transitioning into Thermal Shutdown mode.
Input voltages greater than typically 32 V will cause the LM2937 output to be disabled. When operating with the input voltage greater than the maximum recommended input voltage of 26 V the device performance is not ensured. Continuous operation with the input voltage greater than the maximum recommended input voltage is discouraged.
The LM2937 design does not include any undervoltage lock-out (UVLO), or enable functions. Generally, the output voltage will track the input voltage until the input voltage is greater than VOUT + 1V. When the input voltage is greater than VOUT + 1V the LM2937 will be in linear operation, and the output voltage will be regulated; however, the device will be sensitive to any small perturbation of the input voltage. Device dynamic performance is improved when the input voltage is at least 2 V greater than the output voltage.