Analog Devices Inc. LTC1706EMS-61#TRPBF

Overview

LTC1706EMS-61 from Analog Devices (formerly Linear Technology) is a precision 5-bit VID-controlled resistive ladder IC designed to program the output voltage of 0.6V-reference DC/DC controllers for AMD Opteron CPUs. It delivers ±0.35% output voltage accuracy, supports 0.8V–1.55V in 25mV steps, and integrates 40kΩ pull-up resistors on all five VID inputs. It interfaces directly with regulators including LTC1629-6, LTC3714, LTC3731, and LTC3778 in high-current server power supplies.

For engineers reviewing the LTC1706EMS-61 datasheet, LTC1706EMS-61 pinout, LTC1706EMS-61 application, or LTC1706EMS-61 equivalent, key selection criteria include VID input threshold compatibility (VIL = 0.4V, VIH = 1.6V), SENSE/FB node impedance matching, RFB1–RFB2 ratio stability over temperature, and MSOP-10 thermal performance under sustained 80A load conditions.

Technical Context

The LTC1706EMS-61 implements a digitally programmable resistive divider where VID0–VID4 control discrete resistor taps to adjust the effective RFB2 value while RFB1 remains fixed at ~10kΩ between SENSE and FB pins. Its internal 40kΩ pull-ups with series diodes enable VID inputs to tolerate voltages up to 7V - exceeding VCC - without clamping or damage.

Operation relies on closed-loop feedback: the programmed RFB1/RFB2 ratio sets the regulator's output voltage via the 0.6V reference node (FB), with SENSE connected to the actual output rail. Output accuracy is maintained across –40°C to 85°C ambient, with supply current scaling linearly with grounded VID inputs (IQ ≈ N × (VCC − 0.6V)/40kΩ).

Key Specifications

Pinout & Package

Package: MSOP-10 (3.0mm × 3.0mm × 1.1mm height), thermally enhanced with exposed pad (not electrically connected), θJA = 120°C/W.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar VID-programmable voltage programming applications.

Compared with ISL6549IRZ and TPS51116PWR, the LTC1706EMS-61 provides tighter output accuracy (±0.35% vs ±1.0%), native AMD VID step alignment, and zero-external-component integration - making it the optimal choice for high-reliability Opteron-based infrastructure where regulation stability directly impacts MTBF.

Availability

LTC1706EMS-61 is available at Aetrix Electronics and suitable for AMD Opteron server power supplies, multi-phase CPU core regulators, and large memory array voltage rails requiring stable component supply, long-lifecycle support, and guaranteed parametric consistency across production lots.

Supply support for LTC1706EMS-61 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 its high-performance power management portfolio. Linear pioneered precision analog ICs for demanding industrial and computing applications.

The LTC1706EMS-61 belongs to Linear's VID-programmable voltage setpoint product line, engineered specifically for AMD processor power delivery - emphasizing accuracy, thermal stability, and seamless integration with PolyPhase® and single-phase synchronous buck controllers.

FAQ

What is the function of the NC pin on the LTC1706EMS-61?

The NC (No Connect) pin on the LTC1706EMS-61 is Pin 8 and is internally unconnected. It must remain unpopulated and unstubbed on the PCB layout to prevent parasitic coupling or unintended current paths. This pin corresponds to an unbonded die pad and has no electrical function in the LTC1706EMS-61 circuit operation or thermal path.

Can the LTC1706EMS-61 be used with non-Linear Technology regulators?

The LTC1706EMS-61 can be used with any DC/DC controller featuring a 0.6V internal reference and a high-impedance feedback (FB) pin, provided the SENSE–FB resistive divider architecture matches. It has been validated with LTC1629-6, LTC3714, LTC3731, and LTC3778, but third-party controllers must be tested for RFB1/RFB2 ratio compatibility and VID input leakage tolerance before deployment.

What happens when all five VID inputs are left floating on the LTC1706EMS-61?

When all five VID inputs (VID0–VID4) are floating, the LTC1706EMS-61 produces a regulated 0.775V output at the SENSE pin - corresponding to AMD's "no CPU present" shutdown code (11111). This state is intentional and safe, allowing system-level detection of CPU absence without requiring external pull-downs or firmware intervention.

How does the built-in diode on each VID input protect the LTC1706EMS-61?

Each VID input on the LTC1706EMS-61 includes a series diode between the 40kΩ pull-up resistor and VCC. This diode blocks reverse current flow, allowing VID signals up to 7V (absolute max) to be applied safely even when VCC is 3.3V or 5V - preventing clamping, latch-up, or ESD damage during hot-plug or mixed-voltage signaling scenarios.

Is the LTC1706EMS-61 pin-compatible with earlier LTC1706 variants like LTC1706EMS-60?

No, the LTC1706EMS-61 is not pin-compatible with LTC1706EMS-60. The -61 variant implements the full AMD Opteron VID table (0.8V–1.55V in 25mV steps), while the -60 variant targets different voltage ranges and VID code mappings. Pin functions are identical, but output voltage decoding logic differs - substituting one for the other will result in incorrect core voltage settings.