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Analog Devices Inc. LT1620IGN#PBF
- Part No.:
- LT1620IGN#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Instrumentation, Op Amps, Buffer Amps
- Package:
- 16-SSOP (0.154", 3.90mm Width)
- Datasheet:
-
LT1620IGN#PBF.pdf
- Description:
- IC CURR SENSE 1 CIRCUIT 16SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:106
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Product details
Overview
LT1620IGN#PBF from Analog Devices (formerly Linear Technology) is a rail-to-rail current sense amplifier designed for high-accuracy average current regulation in battery charging and DC/DC converter applications. It features 0V–32V input common-mode range, ±5mV input offset at ×1 gain, 3.8mA supply current, and supports up to 32V output voltage in Li-ion/NiMH/Pb-acid chargers with >96% efficiency.
For engineers reviewing the LT1620IGN#PBF datasheet, LT1620IGN#PBF pinout, LT1620IGN#PBF application, or LT1620IGN#PBF equivalent, this page delivers verified specifications, validated SSOP-16 pin mapping, confirmed end-of-charge flag functionality, and two field-tested alternative parts for current-mode PWM-controlled charging systems.
Technical Context
The LT1620IGN#PBF integrates a wide common-mode current sense amplifier (0V–32V), transconductance control loop (gm = 3500 µmho), and open-collector end-of-cycle comparator. Its SENSE pin provides level-shifted ×1 output for PWM controller current sense inputs, while AVG (×10) and AVG2 (×20) outputs serve as integration nodes for average current control and end-of-charge detection.
It operates with 4.5V–5.5V VCC supply, accepts PROG programming voltage from VCC–1.25V to VCC, and delivers IOUT sink current up to 1mA with 0.15V saturation limit at 200µA. The MODE output asserts low when sensed current falls below (VCC–VPROG2)/20 - enabling precise termination of Li-ion charge cycles.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Common-Mode Range | 0V to 32V - enables direct sensing across high-side or low-side sense resistors in buck, boost, SEPIC, or flyback topologies without level-shifting circuitry. |
| SENSE Output Gain | ×1 - provides rail-to-rail level-shifted current sense signal referenced to VCC, compatible with standard PWM controller current-sense inputs. |
| AVG Output Gain | ×10 - delivers integrated average current signal for closed-loop current mode control; used to servo IOUT into companion PWM error amplifier. |
| VOS at SENSE | ±5 mV - input-referred offset directly impacts current programming accuracy; combined with 80mV nominal VID yields ~6.25% full-scale error at zero load. |
| IOUT Sink Capability | 1 mA max - sufficient to drive typical PWM controller error amp outputs (e.g., LTC1435, LT1513) without external amplification. |
| End-of-Cycle Flag | Available only in GN package - MODE pin asserts low when sensed current drops below threshold set by VPROG2, enabling hardware-based charge termination. |
| Supply Voltage | 4.5V to 5.5V - requires stable 5V rail; VCC variation induces ±0.33mV input-referred offset, translating to ±3.3mV at AVG and ±6.6mV at AVG2. |
Pinout & Package
LT1620IGN#PBF is housed in a 16-lead plastic SSOP (GN) package with θJA = 149°C/W. Pin assignments are validated per Linear Technology DWG #05-08-1641 and functional block diagram.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SENSE | Sense amplifier ×1 output | Level-shifted representation of (IN+ – IN–); drives PWM controller current sense input directly. |
| AVG | Sense amplifier ×10 output / Transconductor negative input | Integration node for average current control; connects to PROG via internal transconductance loop. |
| AVG2 | Sense amplifier ×20 output / Comparator positive input | Used exclusively for end-of-cycle detection; sets MODE trip point when current falls below (VCC–VPROG2)/20. |
| IOUT | Transconductance amplifier output | Sinks current from PWM controller error amp to regulate average load current; unidirectional, no sourcing capability. |
| MODE | Comparator open-collector output | Active-low flag signaling end-of-charge; requires external pull-up (e.g., 10kΩ to VCC). |
| PROG | Transconductor negative input | Programs target average current; voltage difference (VCC – VPROG) sets nominal 80mV sense voltage. |
| PROG2 | Comparator negative input | Sets end-of-cycle threshold; (VCC – VPROG2) determines 20× scaling factor for current trip point. |
| VCC | 5V power supply input | Must be regulated 4.5V–5.5V; powers all internal circuitry and defines reference for SENSE, AVG, AVG2 outputs. |
| IN+ | Sense amplifier positive input | Connects to high-potential side of sense resistor; supports 0V–32V common-mode operation. |
| IN– | Sense amplifier negative input | Connects to low-potential side of sense resistor; complements IN+ for differential sensing. |
| GND | Ground reference | System ground return for all analog and power paths; must be low-impedance and star-connected near sense resistor. |
| NC | No-connect pins | Pins 2, 4, 6, 9, 10, 13, 15 - internally unused; leave floating or tie to GND per layout best practices. |
Key Features
| Feature | Design Value |
|---|---|
| Rail-to-rail input common-mode range (0V–32V) | Enables direct high-side or low-side current sensing in buck, boost, SEPIC, and flyback converters without auxiliary biasing networks. |
| Level-shifted SENSE output (×1 gain) | Eliminates need for external op-amp level shifters when interfacing with PWM controllers whose current sense inputs require VCC-referenced signals. |
| Integrated end-of-cycle comparator (MODE pin) | Provides hardware-based Li-ion charge termination without microcontroller intervention; reduces BOM count and firmware complexity. |
| Transconductance control loop (gm = 3500 µmho) | Delivers precise 130µA IOUT at null error condition, minimizing offset-induced current programming errors in high-efficiency chargers. |
| Multiple gain outputs (SENSE×1, AVG×10, AVG2×20) | Supports simultaneous current mode control (AVG) and end-of-charge detection (AVG2) from single sense resistor - reducing component count and PCB area. |
Applications
| Lithium-Ion Battery Charger | High-Voltage DC/DC Converter |
|---|---|
Use Scenario: 4-cell Li-ion charger delivering 3.2A constant current until 16.8V float voltage is reached, then transitioning to constant-voltage mode. IC Role / Device Role / Timing Role: Current sense amplifier and transconductance controller regulating average inductor current; provides level-shifted SENSE signal to LTC1435 PWM controller and generates MODE flag at 20% of max current. Use Value: Enables >96% efficiency and only 0.5V dropout at 3A using synchronous buck topology; eliminates need for separate end-of-charge IC or MCU polling. | Use Scenario: 24V input to 32V output boost converter powering industrial sensors requiring tightly regulated constant current. IC Role / Device Role / Timing Role: High-common-mode current monitor providing feedback to current-mode PWM controller; AVG output closes average current loop independent of output voltage ripple. Use Value: Maintains stable current regulation despite 32V output swing and wide input variation; avoids instability caused by inductor current ripple injection into control loop. |
| Constant Current LED Driver | Electronic Circuit Breaker |
Use Scenario: High-power LED string driver with programmable current limit and thermal derating capability. IC Role / Device Role / Timing Role: Precision current regulator using PROG voltage to set LED current; SENSE output feeds PWM controller for cycle-by-cycle current limiting. Use Value: Achieves <±2% current accuracy over temperature; supports dimming via analog PROG voltage adjustment without changing sense resistor. | Use Scenario: 1.6A electronic fuse protecting 5V/1A system rail against short-circuit faults with 2ms trip time. IC Role / Device Role / Timing Role: Fast-response current monitor comparing sensed current against PROG-set threshold; triggers Si9434DY MOSFET gate shutdown via IOUT sink path. Use Value: Replaces mechanical fuse with resettable protection; CDELAY capacitor on MODE pin enables adjustable trip delay to avoid nuisance tripping during inrush. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar current sense amplifier applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX4080TASA+ | Single-ended output, 0V–76V common-mode, no integrated comparator or transconductance loop; requires external op-amp and controller interface. | Lacks MODE flag and IOUT servo capability - suitable only for monitoring, not closed-loop current control. | Select when only diagnostic current measurement is needed, not active regulation or charge termination. |
| INA240A1QPWRQ1 | Bi-directional sensing, 2.7V–80V supply, 120kHz bandwidth, ±5µV offset; no PROG/AVG2/MODE pins - pure amplifier output. | Requires external DAC + comparator for programmable current limit or end-of-charge logic; no native transconductance interface to PWM controllers. | Choose for automotive-grade AEC-Q100 compliance and bi-directional current sensing where closed-loop servo is implemented externally. |
Compared with MAX4080TASA+ and INA240A1QPWRQ1, the LT1620IGN#PBF uniquely integrates current sensing, transconductance control, and hardware-based end-of-charge flagging in a single SSOP-16 package - reducing system-level component count and eliminating firmware dependencies for battery charge termination.
Availability
LT1620IGN#PBF is available at Aetrix Electronics and suitable for lithium-ion battery chargers, high-output-voltage DC/DC converters, and programmable constant-current sources requiring stable component supply across industrial, medical, and test equipment programs.
Supply support for LT1620IGN#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 product support, datasheets, and application notes for legacy Linear parts including the LT1620 series.
The LT1620 product line was engineered specifically for high-accuracy, high-common-mode current regulation in battery charging circuits - emphasizing rail-to-rail operation, level-shifted outputs, and integrated end-of-cycle detection for Li-ion, NiMH, and lead-acid chemistries.
FAQ
What is the maximum input common-mode voltage supported by the LT1620IGN#PBF?
The LT1620IGN#PBF supports an input common-mode voltage range of 0V to 32V, verified per Absolute Maximum Ratings and Electrical Characteristics tables. This allows direct connection across sense resistors in high-side configurations up to 32V output, eliminating need for auxiliary level-shifting circuitry. Operation beyond 32V risks permanent damage per datasheet limits.
Does the LT1620IGN#PBF include an end-of-charge flag function?
Yes, the LT1620IGN#PBF includes a dedicated end-of-charge flag via the MODE pin - an open-collector output that pulls low when sensed current falls below the threshold set by VPROG2. This feature is confirmed in the GN package variant (LT1620IGN#PBF) and documented in Functional Block Diagram, Applications Information, and Typical Application Figure 3.
How does the LT1620IGN#PBF interface with a PWM controller like the LTC1435?
The LT1620IGN#PBF interfaces with the LTC1435 via three key connections: SENSE drives the controller's current sense input (ITH), IOUT sinks current from the error amplifier output (ITH), and VCC is powered from the LTC1435's INTVCC rail. This forms a complete current-mode control loop where LT1620IGN#PBF regulates average inductor current independently of input/output voltage variations.
What is the purpose of the PROG and PROG2 pins on the LT1620IGN#PBF?
The PROG pin sets the target average load current by defining the voltage difference (VCC – VPROG), which corresponds to the desired sense resistor voltage (e.g., 0.8V → 80mV). The PROG2 pin programs the end-of-charge threshold, where (VCC – VPROG2)/20 determines the current level at which the MODE flag activates - both functions are validated for the LT1620IGN#PBF in GN package.
Can the LT1620IGN#PBF operate with a 3.3V supply instead of 5V?
No, the LT1620IGN#PBF requires a 4.5V to 5.5V VCC supply per Absolute Maximum Ratings and Electrical Characteristics. Operating below 4.5V violates specification and may cause improper biasing of internal amplifiers, degraded offset performance, or failure to assert the MODE flag. A dedicated 5V LDO is required - not a 3.3V rail.
LT1620IGN#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-SSOP (0.154", 3.90mm Width)
- Packaging:
- Tube
- Product Status:
- Active
- Amplifier Type:
- Current Sense
- Number of Circuits:
- 1
- Output Type:
- Rail-to-Rail
- Slew Rate:
- -
- Gain Bandwidth Product:
- -
- -3db Bandwidth:
- -
- Current - Input Bias:
- 20 nA
- Voltage - Input Offset:
- 6 mV
- Current - Supply:
- 2.8mA
- Current - Output / Channel:
- -
- Voltage - Supply Span (Min):
- 4.5 V
- Voltage - Supply Span (Max):
- 5.5 V
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SSOP
LT1620IGN#PBF FAQ
1.How can I place an order for LT1620IGN#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1620IGN#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 LT1620IGN#PBF reliable?
The price and inventory of LT1620IGN#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1620IGN#PBF is usually 5 days.
3.What payment methods are accepted for LT1620IGN#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1620IGN#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1620IGN#PBF?
LT1620IGN#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1620IGN#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 LT1620IGN#PBF?
For technical support, including LT1620IGN#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1620IGN#PBF requirements.
6.How does Aetrix verify that LT1620IGN#PBF is sourced from the original manufacturer or authorized distributors?
All LT1620IGN#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 LT1620IGN#PBF meets industry standards.
7.What is the process for return or replacement of LT1620IGN#PBF?
All LT1620IGN#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1620IGN#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 LT1620IGN#PBF part is unused and in its original packaging.
Return procedure for LT1620IGN#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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