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Analog Devices Inc. LTC1438IG#PBF
- Part No.:
- LTC1438IG#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 28-SSOP (0.209", 5.30mm Width)
- Datasheet:
-
LTC1438IG#PBF.pdf
- Description:
- IC REG CTRLR BUCK 28SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,842
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Product details
Overview
LTC1438IG#PBF from Analog Devices (formerly Linear Technology) is a dual synchronous step-down switching regulator controller driving external N-channel MOSFETs in a phase-lockable fixed-frequency architecture. It delivers two independently regulated outputs (1.19V–9V), supports 3.5V–30V input, maintains constant frequency down to ~1% load via Adaptive Power™ mode, and integrates a 0.5A low-noise linear regulator for VPP or audio supply - used in notebook computers and portable instrumentation.
For engineers reviewing the LTC1438IG#PBF datasheet, LTC1438IG#PBF pinout, LTC1438IG#PBF application, or LTC1438IG#PBF equivalent, key selection criteria include dual-channel current-mode control, programmable output voltage via VPROG pins, remote sense capability on VOSENSE2, 28-lead SSOP package with verified pin mapping, and compatibility with external PNP-based auxiliary regulation.
Technical Context
The LTC1438IG#PBF implements a constant-frequency, current-mode dual buck controller with independent error amplifiers per channel, where ITH1/ITH2 set peak current thresholds via external sense resistors. Its Adaptive Power™ architecture dynamically routes gate drive between TGL/TGS (high-current) and BG (bottom-FET) pins to sustain 400kHz operation at light loads while minimizing switching losses.
It features a secondary feedback input (SFB1) forcing continuous conduction for primary-output regulation under secondary-winding load conditions, plus integrated functions including power-on reset (POR2), low-battery detection (LBI/LBO), and PLL synchronization (on LTC1439 only - not present in LTC1438IG#PBF).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.5V to 30V (36V absolute max); enables direct use across wide battery and DC distribution rails. |
| Output Voltage Range | 1.19V to 9V per channel; selectable via VPROG1/VPROG2 pins or external divider on VOSENSE2. |
| Switching Frequency | Programmable up to 400kHz via COSC capacitor; fixed-frequency operation maintained down to ~1% load. |
| Efficiency Mode | Adaptive Power™ mode reduces gate charge loss at light loads; Burst Mode default if TGS pins left open. |
| Auxiliary Regulator | 0.5A linear regulator with AUXON control and AUXFB feedback; supports 12V (via internal divider) or adjustable outputs. |
| Shutdown Current | <30µA (IQ); achieved by pulling RUN/SS1 and RUN/SS2 below 1.3V for micropower system standby. |
| Package | 28-lead plastic SSOP (G package); thermal resistance θJA = 95°C/W; RoHS-compliant #PBF suffix. |
Pinout & Package
Package: 28-lead plastic SSOP (G package), 0.025" pitch, exposed pad not present. Thermal performance rated at θJA = 95°C/W.
| Pin | Circuit Role | Design Meaning |
|---|---|---|
| 1 | SENSE+ 1 | Non-inverting input of current comparator for Channel 1; used with RSENSE1 to set overcurrent threshold. |
| 2 | SENSE– 1 | Inverting input of current comparator for Channel 1; internally tied to VOUT1 sensing point (except LTC1438-ADJ). |
| 3 | VPROG1 | Attenuator select for Channel 1 output voltage; 0V = 3.3V, INTVCC = 5V, open = adjustable via VOSENSE1 (LTC1438-ADJ only). |
| 4 | ITH1 | Error amplifier output for Channel 1; controls peak inductor current via voltage-dependent current limit. |
| 5 | POR2 | Open-drain power-on reset output for Channel 2; asserts low when VOUT2 drops >7.5%, releases after 65536 cycles. |
| 6 | COSC | Oscillator timing node; sets fSW via external capacitor (e.g., 100pF → 125kHz typical). |
| 7 | SGND | Small-signal ground reference for all analog circuitry; must be routed separately from PGND to avoid noise coupling. |
| 8 | LBI | Low-battery comparator input; referenced to 1.19V internal bandgap; triggers LBO when voltage falls below 1.19V. |
| 9 | LBO | Open-drain low-battery output; sinks current when LBI < 1.19V; requires external pull-up. |
| 10 | SFB1 | Secondary winding feedback input for Channel 1; forces continuous operation when pulled <1.19V. |
| 11 | ITH2 | Error amplifier output for Channel 2; identical function to ITH1 but for second regulator loop. |
| 12 | VOSENSE2 | Remote sense input for Channel 2; accepts feedback from external divider or directly from VOUT2. |
| 13 | SENSE– 2 | Inverting input of current comparator for Channel 2; connects to (–) side of RSENSE2. |
| 14 | SENSE+ 2 | Non-inverting input of current comparator for Channel 2; completes current-sense path with SENSE– 2. |
| 15 | RUN/SS1 | Channel 1 run control and soft-start input; 3µA current source charges CSS to enable startup ramp. |
| 16 | BOOST 1 | Topside driver supply for Channel 1; powers floating gate driver for TGL1/TGS1; tied to bootstrap capacitor. |
| 17 | TGL1 | High-current top-gate drive for Channel 1; drives large N-MOSFET; disabled during Adaptive Power™ low-load mode. |
| 18 | SW1 | Switch node for Channel 1 inductor; swings from –0.3V to VIN + 5V; high di/dt path requiring tight layout. |
| 19 | TGS1 | Small top-gate drive for Channel 1; active in Adaptive Power™ low-load mode; drives Schottky-assisted MOSFET. |
| 20 | VIN | Main input supply; powers internal circuits and provides source for boost capacitors; decoupling critical at PGND. |
| 21 | BG1 | Bottom-gate drive for Channel 1; drives N-MOSFET source to PGND; active in both continuous and Adaptive Power™ modes. |
| 22 | INTVCC | Internal 5V regulator output; powers logic, drivers, and error amps; bypassed with ≥2.2µF tantalum to PGND. |
| 23 | PGND | Power ground for bottom MOSFET sources and CIN negative terminal; separate from SGND to minimize noise. |
| 24 | BG2 | Bottom-gate drive for Channel 2; identical function to BG1 but for second channel. |
| 25 | EXTVCC | External supply input for INTVCC switch; bypasses internal LDO when >4.7V; max 10V rating. |
| 26 | SW2 | Switch node for Channel 2 inductor; same voltage swing and layout rules as SW1. |
| 27 | TGL2 | High-current top-gate drive for Channel 2; disabled during low-load Adaptive Power™ operation. |
| 28 | RUN/SS2 | Channel 2 run control and soft-start input; independent of RUN/SS1 for asymmetric enable sequencing. |
Key Features
| Feature | Design Value |
|---|---|
| Adaptive Power™ Architecture | Automatically switches between TGL/BG (high-current) and TGS/BG (low-current) drive paths to sustain fixed 400kHz operation down to ~1% load without efficiency collapse. |
| Dual Independent Control Loops | Separate ITH1/ITH2, VPROG1/VPROG2, and VOSENSE2 allow fully independent output voltage, current limit, and remote sensing per channel. |
| Integrated Auxiliary Linear Regulator | 0.5A PNP-based regulator with AUXON enable, AUXFB feedback, and automatic 12V/adjustable mode selection based on AUXDR voltage level. |
| Secondary Feedback Enforcement (SFB1) | Pulling SFB1 <1.19V forces Channel 1 into continuous conduction - essential for maintaining regulation when secondary winding supplies auxiliary loads. |
| Logic-Controlled Micropower Shutdown | IQ <30µA achieved by pulling both RUN/SS1 and RUN/SS2 below 1.3V; no external bias required for ultra-low standby power. |
Applications
| Portable Medical Instrumentation | Notebook Computer Power Management |
|---|---|
Use Scenario: Battery-powered handheld ECG or glucose meter requiring clean, stable dual-rail supplies (3.3V logic + 5V sensor interface) with minimal thermal rise. IC Role / Device Role / Timing Role: Dual synchronous buck controller delivering regulated outputs while maintaining constant switching frequency across 10µA–3.5A load range via Adaptive Power™. Use Value: Eliminates audible coil whine during low-power monitoring mode and sustains >90% efficiency at 100mA load without Burst Mode noise. | Use Scenario: Mainboard VRM supplying core logic (5V) and I/O (3.3V) from shared 12V or 19V adapter input in space-constrained clamshell design. IC Role / Device Role / Timing Role: Dual-channel current-mode controller with independent soft-start (RUN/SS1/RUN/SS2) and remote sense (VOSENSE2) for precise load-point regulation. Use Value: Enables single-chip dual-output solution with <±0.8% load regulation and coordinated power sequencing - reducing BOM count vs discrete controllers. |
| Industrial Portable Test Equipment | DC Power Distribution Systems |
Use Scenario: Handheld multimeter or oscilloscope with isolated analog front-end requiring ultra-low-noise 3.3V supply and 12V VPP for EEPROM programming. IC Role / Device Role / Timing Role: Primary buck controller (Channel 1) + auxiliary linear regulator (AUXFB/AUXON) generating low-noise 12V from same VIN rail. Use Value: Integrates switching and linear regulation in one IC - eliminating need for separate LDO and simplifying layout while meeting <10µV RMS noise spec. | Use Scenario: Telecom remote radio unit powered from 48V PoE-derived supply needing efficient 5V/3.3V conversion with fault reporting and brownout detection. IC Role / Device Role / Timing Role: Dual buck controller with LBI/LBO comparator inputs and POR2 output providing system-level power-good signaling and undervoltage lockout. Use Value: Delivers deterministic power sequencing, brownout response (<1.19V trip), and reset assertion (65536-cycle delay) - enabling robust firmware recovery without external supervisors. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual synchronous buck controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC1439IG#PBF | Includes full PLL synchronization (PLLIN/PLL LPF pins) and additional SFB2 pin; otherwise pin-compatible and functionally identical in non-PLL use cases. | Required where external clock synchronization (e.g., to system master clock) is mandatory; supports tighter EMI control via frequency alignment. | Select LTC1439IG#PBF only if PLL lock capability is needed; LTC1438IG#PBF is preferred for cost-sensitive, standalone dual-buck designs without sync requirements. |
| TPS54290RGTR | Single-channel, integrated FET (not controller); 4.5–20V input; fixed 3.3V/5V options only; no auxiliary linear regulator or SFB1 functionality. | Applicable only for single-rail systems; lacks secondary feedback enforcement and dual independent programming. | Choose TPS54290RGTR for simpler, lower-component-count single-output designs where integrated FETs reduce board area - not a functional substitute for dual-channel, controller-based architectures. |
Compared with LTC1439IG#PBF, the LTC1438IG#PBF omits PLL circuitry - reducing cost and complexity for unsynchronized applications - while retaining identical dual-channel control, Adaptive Power™, and auxiliary regulation. Versus TPS54290RGTR, it offers true dual independent outputs, external FET flexibility, and advanced features like SFB1 enforcement, making it suitable for demanding multi-rail embedded systems.
Availability
LTC1438IG#PBF is available at Aetrix Electronics and suitable for notebook computers, portable instrumentation, and battery-operated devices requiring stable component supply with guaranteed long-term availability and full traceability.
Supply support for LTC1438IG#PBF includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Analog Devices acquired Linear Technology in 2017 and maintains full support for legacy Linear power management ICs including the LTC1438 series.
The LTC1438 product line was designed specifically for high-efficiency dual-output DC/DC conversion in space- and thermally-constrained portable electronics, emphasizing adaptive light-load operation and integrated auxiliary regulation.
FAQ
What is the maximum supported switching frequency for the LTC1438IG#PBF?
The LTC1438IG#PBF supports a maximum switching frequency of 400kHz, set by the COSC capacitor value. Operation above this frequency is not characterized and may degrade efficiency or stability. The typical oscillator frequency with a 100pF COSC is 125kHz, and higher values scale inversely - e.g., 56pF yields ~200kHz. Always verify loop stability and thermal performance at elevated frequencies using the recommended compensation network.
Does the LTC1438IG#PBF support remote voltage sensing on both outputs?
The LTC1438IG#PBF supports remote voltage sensing on Channel 2 via the VOSENSE2 pin, which accepts feedback from an external resistive divider across VOUT2. Channel 1 remote sensing is only available on the LTC1438IG#PBF-ADJ variant; standard LTC1438IG#PBF ties SENSE–1 internally to VOUT1 and does not expose VOSENSE1. Therefore, only one channel (Channel 2) supports true remote sense in the base LTC1438IG#PBF configuration.
How does the Adaptive Power™ mode operate in the LTC1438IG#PBF?
Adaptive Power™ mode in the LTC1438IG#PBF dynamically shifts gate drive from TGL1/TGL2 (high-current top-FET drivers) to TGS1/TGS2 (small top-FET drivers) when load current drops below ~1% of full scale. This preserves fixed-frequency operation and avoids Burst Mode noise while minimizing gate charge losses. The transition is triggered by current reversal detection (I2 comparator) and hysteresis monitoring of RSENSE voltage - ensuring seamless, low-ripple light-load performance without external intervention.
Can the auxiliary regulator in the LTC1438IG#PBF generate voltages other than 12V?
Yes - the auxiliary regulator in the LTC1438IG#PBF can generate adjustable outputs below 12V. When AUXDR voltage is below 8.5V, the internal 12V resistive divider disconnects, allowing an external feedback divider from AUXDR to SGND to set any output voltage within the PNP pass device's compliance range. The AUXFB pin serves as the error amplifier input, and the AUXON pin enables/disables regulation. This makes it suitable for low-noise 3.3V or 5V auxiliary supplies in addition to 12V VPP generation.
Is the LTC1438IG#PBF pin-compatible with the LTC1439IG#PBF?
Yes, the LTC1438IG#PBF and LTC1439IG#PBF share identical pinouts and package (28-lead SSOP), and all common pins function identically. The LTC1439IG#PBF adds two extra pins - PLLIN and PLL LPF - which are NC (no-connect) on the LTC1438IG#PBF. Therefore, LTC1438IG#PBF can be used as a drop-in replacement in LTC1439IG#PBF designs where PLL functionality is unused, provided the PLLIN and PLL LPF pins are tied to SGND per datasheet recommendations.
LTC1438IG#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 28-SSOP (0.209", 5.30mm Width)
- Packaging:
- Tube
- Product Status:
- Active
- Output Type:
- Transistor Driver
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Number of Outputs:
- 2
- Output Phases:
- 1
- Voltage - Supply (Vcc/Vdd):
- 3.5V ~ 30V
- Frequency - Switching:
- Up to 400kHz
- Duty Cycle (Max):
- 99%
- Synchronous Rectifier:
- Yes
- Clock Sync:
- No
- Serial Interfaces:
- -
- Control Features:
- Enable, Power on Reset, Soft Start
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-SSOP
LTC1438IG#PBF FAQ
1.How can I place an order for LTC1438IG#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1438IG#PBF on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for LTC1438IG#PBF reliable?
The price and inventory of LTC1438IG#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1438IG#PBF is usually 5 days.
3.What payment methods are accepted for LTC1438IG#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1438IG#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1438IG#PBF?
LTC1438IG#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1438IG#PBF order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for LTC1438IG#PBF?
For technical support, including LTC1438IG#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1438IG#PBF requirements.
6.How does Aetrix verify that LTC1438IG#PBF is sourced from the original manufacturer or authorized distributors?
All LTC1438IG#PBF products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that LTC1438IG#PBF meets industry standards.
7.What is the process for return or replacement of LTC1438IG#PBF?
All LTC1438IG#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1438IG#PBF, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The LTC1438IG#PBF part is unused and in its original packaging.
Return procedure for LTC1438IG#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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