DocumentationDatasheet
Application Note
Design Note
Reliability Data
LT Journal
- 2MHz Dual DC/DC Controller Halves Settling Time of Load Release Transients, Features 0.67% Differential VOUT Accuracy and Is Primed for High Step-Down Ratios
- Dual, Fast, Step-Down Controller’s External Reference Input Enables Dynamic Voltage Scaling from 0.4V to 5.5V and 0.3% Total Combined Regulation Accuracy
Press Release
cad_symbol
ltspice
- LTC3838 Demo Circuit - Wide Input Range, High Efficiency Step-Down DC/DC Converter with Inductor DCR Current Sensing (4.5-26V to 1.2V @ 15A & 1.5V & 15A)
- LTC3838 Demo Circuit - Wide Input Range, High Efficiency Step-Down DC/DC Converter with Rsense Current Sensing (4.5-26V to 1.2V @ 15A & 1.5V @ 15A)
LTpowerCAD
- LTC3838 Project - Dual, Fast, Accrate Step-Down DC/DC Converter with Inductor DCR Current Sensing (4.5-14V to 1.2V @ 20A & 1.5V @ 20A)
- LTC3838 Project - Dual, Fast, Accrate Step-Down DC/DC Converter with Inductor DCR Current Sensing (4.5-26V to 1.2V @ 15A & 1.5V & 15A)
- LTC3838 Project - Dual, Fast, Accrate Step-Down DC/DC Converter with Rsense Current Sensing (4.5-26V to 1.2V @ 15A & 1.5V & 15A)
- LTC3838 Project - Dual, Fast, Accrate Step-Down DC/DC Converter with Rsense Current Sensing (4.5-14V to 1.2V @ 20A & 1.5V @ 20A)
Features
- Wide VIN Range: 4.5V to 38V, VOUT: 0.6V to 5.5V
- ±0.67% Output Voltage Accuracy Over Temperature, Differential Output Voltage Sensing, Allowing Up to ±500mV Line Loss at Remote Ground on Channel 1
- ±1% Output on the Independent 2nd Channel
- Controlled On-Time, Valley Current Mode Control
- Fast Load Transient Response
- Detect Transient (DTR) Reduces VOUT Overshoot
- Frequency Programmable from 200kHz to 2MHz, Synchronizable to External Clock
- tON(MIN) = 30ns, tOFF(MIN) = 90ns
- RSENSE or Inductor DCR Current Sensing
- Overvoltage Protection and Current Limit Foldback
- Power Good Output Voltage Monitor
- Output Voltage Tracking and Adjustable Soft Start-Up
- Thermally Enhanced 38-Pin (5mm × 7mm) QFN and TSSOP packages
Typical Application
Description
The LTC®3838 is a dual, PolyPhase® synchronous step-down DC/DC switching regulator controller. Two independent channels drive all N-channel power MOSFETs. The controlled on-time, valley current mode control architecture allows for fast transient response and constant frequency switching in steady-state operation, independent of VIN, VOUT and load current. Its load-release transient detection feature significantly reduces overshoot at low output voltages.
Differential output voltage sensing, along with a precision internal reference, offers an accurate ±0.67% output regulation on Channel 1, even if the remote output ground deviates from local ground by ±500mV. The second channel can either provide an independent ±1% output, or together with the first channel of this controller, serve as one of the PolyPhase channels for a single-output voltage.
The switching frequency can be programmed from 200kHz to 2MHz with an external resistor, and can be synchronized to an external clock. Very low tON and tOFF times allow for near 0% and near 100% duty cycles, respectively. Voltage tracking soft start-up and multiple safety features are provided.
| Part Number | Description |
|---|---|
| LTC3838 | ±0.67% Differential Output Voltage Accuracy Over Temperature on Channel 1, ±1% Output Regulation on Channel 2, Separate Per Channel 30mV to 100mV Current Sense Range Controls |
| LTC3838-1 | ±0.67% Differential Output Voltage Accuracy Over Temperature on Both Channel 1 and Channel 2, Single Pin 30mV/60mV Current Sense Range Controls |
| LTC3838-2 | ±0.67% Differential Output Voltage Accuracy With Internal Reference on Channel 1, ±4mV Differential with External Reference Voltage on Channel 2, Fixed 30mV Current Sense Range |
5x7 QFN-38,TSSOP-38
Package Variations and Pricing
| Part Number | Package | Pins | Temp | Price (1-99) |
Price (1k)* |
|---|---|---|---|---|---|
| LTC3838EFE#PBF | TSSOP | 38 | E | $4.86 | $3.40 |
| LTC3838EFE#TRPBF | TSSOP | 38 | E | $3.46 | |
| LTC3838EUHF#PBF | QFN | 38 | E | $4.54 | $3.18 |
| LTC3838EUHF#TRPBF | QFN | 38 | E | $3.24 | |
| LTC3838EUHF-1#PBF | QFN | 38 | E | $4.54 | $3.18 |
| LTC3838EUHF-1#TRPBF | QFN | 38 | E | $3.24 | |
| LTC3838EUHF-2#PBF | QFN | 38 | E | $4.54 | $3.18 |
| LTC3838EUHF-2#TRPBF | QFN | 38 | E | $3.24 | |
| LTC3838IFE#PBF | TSSOP | 38 | I | $5.54 | $3.88 |
| LTC3838IFE#TRPBF | TSSOP | 38 | I | $3.94 | |
| LTC3838IUHF#PBF | QFN | 38 | I | $5.13 | $3.59 |
| LTC3838IUHF#TRPBF | QFN | 38 | I | $3.65 | |
| LTC3838IUHF-1#PBF | QFN | 38 | I | $5.13 | $3.59 |
| LTC3838IUHF-1#TRPBF | QFN | 38 | I | $3.65 | |
| LTC3838IUHF-2#PBF | QFN | 38 | I | $5.13 | $3.59 |
| LTC3838IUHF-2#TRPBF | QFN | 38 | I | $3.65 |
Linear Technology offers many demo boards free of charge to qualified customers. Contact your local sales office or distributor to inquire about a demo board. Certain demo boards are also available for sale via credit card on this website. Demo boards are for evaluation purposes only. It remains the customer’s responsibility to verify proper and reliable operation in the actual end application.
| Part Number | Description | Price | Documentation |
|---|---|---|---|
| DC1626A-A | LTC3838EFE Demo Board (DCR Sense) | 4.5V ≤ VIN ≤ 26V; VOUT1 = 1.2V @ 15A, VOUT2 = 1.5V @ 15A | $150.00 | |
| DC1626A-B | LTC3838EFE Demo Board (RSENSE) |4.5V ≤ VIN ≤ 26V; VOUT1 = 1.2V @ 15A, VOUT2 = 1.5V @ 15A | $150.00 | |
| DC1801A-A | LTC3838EUHF Demo Board (DCR Sense) | VIN = 4.5V to 14V, VOUT1 = 1.2V @ 20A, VOUT2 = 1.5V @ 20A | $150.00 | |
| DC1801A-B | LTC3838EUHF Demo Board (RSENSE) | VIN = 4.5V to 14V, VOUT1 = 1.2V @ 20A, VOUT2 = 1.5V @ 20A | $150.00 |