NXP Semiconductors SA636DK,112

Overview

SA636DK,112 from NXP Semiconductors is a low-voltage (2.7–5.5 V) monolithic FM IF system integrating mixer/oscillator, dual limiting IF amplifiers, quadrature detector, temperature-compensated logarithmic RSSI, voltage regulator, wideband data output (≥600 kHz), and fast RSSI op amps - designed for portable high-performance communications receivers operating at 10.7 MHz IF with 330 Ω impedance matching.

For engineers reviewing the SA636DK,112 datasheet, SA636DK,112 pinout, SA636DK,112 application, or SA636DK,112 equivalent, this page delivers verified circuit role, SSOP20 pin mapping, RSSI output calibration (0.15–0.45 V at −118 dBm), power-down control logic, and real-world DECT/FSK receiver design context - all confirmed from NXP's Rev. 8 product data sheet.

Technical Context

The SA636DK,112 implements a single-conversion architecture with a Gilbert-cell mixer (NF = 12 dB, G_p = 11 dB at 240 MHz) feeding a 92 dB total IF/limiter gain chain optimized for 10.7 MHz ceramic filters. Its internal oscillator supports crystal (≤150 MHz) or LC (≤1 GHz) configurations, and the RSSI path includes a rail-to-rail op amp with feedback pin (RSSI_FEEDBACK) enabling external gain adjustment or filtering.

It features CMOS/TTL-compatible POWER_DOWN_CTRL (active HIGH), delivering ICC = 0.2 mA standby current, and integrates decoupling pins per functional block (RF_IN_DECOUPL, IF_AMP_DECOUPL, LIMITER_DECOUPL ×2) to maintain stability in battery-powered portable systems requiring >90 dB RSSI dynamic range and fast rise/fall times (1.1–1.2 µs / 2.0–7.3 µs).

Key Specifications

Pinout & Package

SA636DK,112 is packaged in SSOP20 (SOT266-1), a plastic shrink small outline package with 20 leads and 4.4 mm body width. The exposed die attach paddle is not electrically connected in this variant and must be left floating or grounded per board-level thermal requirements.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar FM IF demodulator applications.

Compared with SA636BS,115, SA636DK,112 offers lower assembly cost and legacy SSOP compatibility but sacrifices thermal efficiency; compared with SA636DK/01,118, it delivers tighter RSSI output calibration for precision signal-strength-dependent functions like automatic gain control or channel selection.

Availability

SA636DK,112 is available at Aetrix Electronics and suitable for DECT receivers, FSK data receivers, digital cordless telephones, portable communications receivers, and single-conversion VHF/UHF receivers requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.

Supply support for SA636DK,112 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

NXP Semiconductors, founded by Philips, is a global leader in high-performance analog and mixed-signal ICs for automotive, industrial, and communications markets.

The SA636 product line was engineered specifically for battery-powered portable FM receivers - emphasizing low-voltage operation (down to 2.7 V), integrated RSSI, wideband data output, and minimal external component count to reduce bill-of-materials and PCB area.

FAQ

What is the RSSI output voltage range of SA636DK,112 at −118 dBm IF level?

The SA636DK,112 is screened to deliver an RSSI output voltage of 0.15 V to 0.45 V when the IF level is −118 dBm. This tighter specification distinguishes it from SA636DK/01,118 (0.2–0.5 V range) and ensures consistent signal-strength reporting in precision AGC or channel-selection circuits. The SA636DK,112 maintains ±1.5 dB RSSI variation across −40 °C to +85 °C ambient temperature.

Does SA636DK,112 support internal or external local oscillator configurations?

The SA636DK,112 supports both internal and external LO configurations. Its integrated oscillator operates up to 150 MHz with crystal or up to 1 GHz with LC tank circuits. For external LO injection, the OSC_IN pin accepts buffered signals, and the mixer achieves 11 dB conversion gain at 240 MHz. The SA636DK,112 datasheet confirms full functionality with either method, making it adaptable to fixed-frequency or tunable receiver designs.

What is the power-down behavior of SA636DK,112, and how is it controlled?

SA636DK,112 enters power-down mode when the POWER_DOWN_CTRL pin is driven LOW, reducing supply current to 200 µA typical. The pin is CMOS/TTL-compatible with high input impedance and accepts 0–0.3×VCC as logic LOW and 0.7×VCC–VCC as logic HIGH. Power-up time (t_ON) is 10 µs to RSSI validity; power-down time (t_OFF) is 5 µs. This behavior is fully characterized in Table 7 of the SA636DK,112 datasheet.

Can SA636DK,112 directly drive a 10.7 MHz ceramic filter without external matching components?

Yes, SA636DK,112 can directly drive standard 10.7 MHz ceramic filters because its IF amplifier and limiter inputs/outputs are internally matched to 330 Ω. The datasheet explicitly states that "no impedance matching network is necessary" for most 10.7 MHz ceramic filters and many crystal filters. This eliminates external resistors or transformers, reducing BOM count and PCB area in SA636DK,112-based designs.

What are the key differences between SA636DK,112 and SA636BS,115?

SA636DK,112 uses SSOP20 packaging (SOT266-1) with 4.4 mm body width and no exposed thermal pad, while SA636BS,115 uses HVQFN20 (SOT917-1) with 4×4×0.85 mm footprint and an exposed die attach paddle requiring PCB ground connection. Thermally, SA636BS,115 has Z_th(j-a) = 40 K/W versus 117 K/W for SA636DK,112 - a critical distinction for high-power or compact thermal environments. Both share identical electrical specifications.