The SA571DR2G is a versatile, low-cost dual-gain-control circuit in which either channel may be used as a dynamic-range compressor or expandor. Each channel contains a precision full-wave rectifier that derives a control current from the average value of the signal, and a linearized, temperature-compensated variable-gain cell that adjusts the gain of an external op-amp configuration. Because compression and expansion are complementary operations, a pair of SA571DR2G channels forms a complete compandor link that restores the original signal after transmission through a noisy or amplitude-limited channel.

Internally, each channel references a stable 1.8 V bandgap and a set of trimmed resistors (R1 = 10 kΩ rectifier input, R2 = 20 kΩ ΔG-cell input, R3 = 20 kΩ and R4 = 30 kΩ in the op-amp feedback network). System levels are set with external components, so the designer can tailor the compression ratio, attack/decay time and reference level to the target application. A dedicated THD TRIM pin allows the gain-cell distortion to be nulled from a typical 0.5% down to about 0.1% at 0 dBm, 1 kHz.

The SA571DR2G is the surface-mount (SOIC-16 Wide Body) member of the onsemi SA571/SA572/NE570 compandor family. It is well suited to cellular radio, modems, telephone and satellite broadcast/receive audio systems, and it is equally effective as a high-level limiter, a low-level expandor used as a noise gate, a dynamic filter element or a voltage-controlled amplifier.

Note: Values are taken from the onsemi SA571 data sheet (V_CC = +15 V, T_A = 25 °C unless stated). Design engineers should confirm every parameter against the latest data sheet before committing a design.

The SA571DR2G is supplied in a 16-lead SOIC Wide Body package (onsemi Case 751G, 0.295" / 7.50 mm body width, 1.27 mm lead pitch). The wide-body outline gives more internal die area and better thermal performance than a narrow SOIC, while remaining fully compatible with standard surface-mount assembly and reflow soldering. The "DR2G" suffix denotes tape-and-reel packaging and a Pb-free, RoHS-compliant finish.

The mechanical case outline below shows the body dimensions, lead form and recommended mounting footprint for Case 751G. Use the dimensioned drawing to generate the land pattern and the assembly stencil.

The SA571DR2G has 16 pins arranged as two mirror-image channels around a shared supply and ground. Pins 1–8 serve Channel 1 and pins 9–16 serve Channel 2 (top view):

• Pin 1 / Pin 16 – RECT CAP 1 / RECT CAP 2: Rectifier averaging-capacitor connection; the external capacitor sets the attack and release time constants.
• Pin 2 / Pin 15 – RECT IN 1 / RECT IN 2: Rectifier signal input (through the internal 10 kΩ R1), which derives the gain-control current.
• Pin 3 / Pin 14 – ΔG CELL IN 1 / ΔG CELL IN 2: Variable-gain-cell input (through the internal 20 kΩ R2).
• Pin 4 – GND: Device ground, common to both channels.
• Pin 5 / Pin 12 – INV. IN 1 / INV. IN 2: Inverting input of the channel output op-amp.
• Pin 6 / Pin 11 – RES. R₃ 1 / RES. R₃ 2: Access to the internal 20 kΩ / 30 kΩ feedback network for level setting.
• Pin 7 / Pin 10 – OUTPUT 1 / OUTPUT 2: Op-amp output, ±20 mA drive capability.
• Pin 8 / Pin 9 – THD TRIM 1 / THD TRIM 2: Total-harmonic-distortion trim; an external trim nulls gain-cell distortion.
• Pin 13 – V_CC: Positive supply, 6.0 V to 18 V, common to both channels.

The following alternatives come from the same onsemi compandor family. Before substituting, verify supply range, distortion and the external level-setting network, because the SA571, SA572 and NE570 differ in trimmed performance even though they share the pinout.

Package Comparison

onsemi (ON Semiconductor, NASDAQ: ON), headquartered in Scottsdale, Arizona, USA, is a global supplier of power, sensing and signal-processing semiconductors. The SA571/SA572/NE570 compandor line originated with Signetics/Philips and is now manufactured and supported by onsemi, which maintains the family in Pb-free SOIC and PDIP packages for the audio and communications market.

onsemi publishes the governing SA571 data sheet (document SA571/D) together with the Case 751G mechanical outline used by the SA571DR2G. The data sheet is the authoritative reference for electrical limits, the rectifier/gain-cell architecture and the recommended external network; InFortune Electronics supplies the device and provides sourcing and technical support.