Key Selection Information
| Selection Parameter | Confirmed Information |
|---|---|
| Measurement | Unipolar high-side current sensing |
| Supply / Common Mode | 2.7 V to 36 V recommended |
| Full-Scale Sense Voltage | 100 mV to 500 mV recommended |
| Quiescent Current | 25 µA typical |
| Output Architecture | Current output; external RL sets voltage gain |
| Transfer Core | 5 kΩ internal transconductance network |
| Temperature | −40°C to +125°C |
| Exact Package / Packing | SOT-23 (DBV), 5 pins; 3000-piece large tape and reel |
Product Overview
INA138NA/3K is a low-power high-side current-shunt monitor that converts the differential voltage across a shunt into an output current. The load resistor RL then converts that current into a ground-referenced voltage, allowing the designer to choose voltage gain instead of accepting a fixed-gain device.
For INA138, both the supply and measured bus are intended for 2.7 V to 36 V operation and are electrically independent. The 25 µA typical quiescent current makes the part useful where monitoring overhead must remain small relative to load current.
The /3K order code identifies the 3000-piece large tape-and-reel SOT-23-5 option. It should be retained in procurement records because the /250 variant is the smaller reel option.
For related devices, see HKEQGOO’s Current Sense Amplifiers category.
Technical Specifications
| Parameter | Verified Information |
|---|---|
| Manufacturer | Texas Instruments |
| Exact MPN | INA138NA/3K |
| Measurement | Unipolar high-side current sensing |
| Supply / Common Mode | 2.7 V to 36 V recommended |
| Full-Scale Sense Voltage | 100 mV to 500 mV recommended |
| Quiescent Current | 25 µA typical |
| Output Architecture | Current output; external RL sets voltage gain |
| Transfer Core | 5 kΩ internal transconductance network |
| Temperature | −40°C to +125°C |
| Exact Package / Packing | SOT-23 (DBV), 5 pins; 3000-piece large tape and reel |
| Manufacturer Status | Active / Production |
| Part Marking | B38 |
Functional Highlights
RL sets gain and also changes dynamic behavior
The output stage is a current source, so RL is part of the signal path rather than only a passive load. Larger RL raises output volts per ampere of load current but reduces available output headroom and can reduce bandwidth.
The 36 V limit is an operating limit, not the absolute-maximum headline
TI lists higher stress limits in the absolute-maximum table. Normal design should stay inside the 36 V recommended supply/common-mode range rather than treating the stress rating as usable bus voltage.
Design Considerations
- Choose RS from allowable shunt loss and full-scale sense voltage, then select RL for the desired ADC range.
- Verify maximum VOUT against output compliance at the lowest bus/supply operating point.
- Use Kelvin connections to the shunt so high-current copper resistance is not included in the sensed voltage.
Product Status and Exact Order Code
Manufacturer status: Active / Production
Texas Instruments lists INA138NA/3K as Active / Production; SOT-23 (DBV), 5 pins; 3000-piece large tape and reel; Level-2-260C-1 YEAR; −40°C to +125°C; marking B38.
Related Engineering Resources
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