NXP Semiconductors SA636DK,118

Overview

SA636DK,118 from NXP Semiconductors is a low-voltage (2.7 V min), high-performance FM IF system IC integrating mixer/oscillator, dual limiting IF amplifiers, quadrature detector, temperature-compensated logarithmic RSSI (90+ dB dynamic range), wideband data output (≥600 kHz), and CMOS/TTL-compatible power-down control. It operates in portable communications receivers at 10.7 MHz IF with 330 Ω impedance matching and supports DECT, FSK/ASK data, and single-conversion VHF/UHF architectures.

For engineers reviewing the SA636DK,118 datasheet, SA636DK,118 pinout, SA636DK,118 application, or SA636DK,118 equivalent, this page delivers verified circuit role (FM IF signal processor), key specs (RSSI output voltage at −118 dBm = 0.15–0.45 V for SA636DK/02 variant), package (SSOP20), power-down behavior (ICC = 200 µA), and real-world design meaning of parameters including mixer NF = 12 dB at 240 MHz and limiter gain = 54 dB.

Technical Context

The SA636DK,118 implements a single-conversion FM IF architecture with internal Gilbert cell mixer (NF = 12 dB, Gp = 11 dB at 240 MHz) and oscillator supporting crystal (≤150 MHz) or LC (≤1 GHz) configurations. Its IF chain includes two cascaded limiting amplifiers (total gain ≈ 92 dB) optimized for 10.7 MHz, 330 Ω source applications.

RSSI generation uses temperature-compensated logarithmic detection with rail-to-rail op-amp output (Vo(RSSI) = 0.15–0.45 V at −118 dBm IF level), feedback pin access for external gain/filtering, and fast rise/fall times (1.1–1.2 µs / 2.0–7.3 µs). The DATA_OUT channel provides demodulated baseband with ≥600 kHz bandwidth for wideband digital protocols like DECT.

Key Specifications

Pinout & Package

SA636DK,118 is supplied in SSOP20 (SOT266-1) package: plastic shrink small outline, 20 leads, body width 4.4 mm, pitch 0.65 mm.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SA636DK/01,118 and SA636BS,115, SA636DK,118 offers tighter RSSI output voltage screening (0.15–0.45 V at −118 dBm) for improved signal strength accuracy in DECT and digital cordless telephony, while retaining identical IF gain, noise figure, and power-down functionality in the SSOP20 footprint.

Availability

SA636DK,118 is available at Aetrix Electronics and suitable for DECT handsets, FSK data links, portable cellular receivers, and VHF/UHF scanner front-ends requiring stable component supply, consistent RSSI calibration, and long-term industrial availability.

Supply support for SA636DK,118 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 communication markets.

The SA636 product line was designed specifically for low-voltage, high-bandwidth portable FM receiver applications-including DECT, digital cordless telephones, and single-conversion VHF/UHF radios-emphasizing integration, power efficiency, and RF performance.

FAQ

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

The SA636DK,118 is the SA636DK/02 variant, screened for Vo(RSSI) = 0.15 V to 0.45 V at IF level = −118 dBm. This tighter specification ensures consistent signal strength reporting in DECT and digital cordless telephone applications where RSSI accuracy directly impacts handover and channel selection reliability. The SA636DK,118 maintains the same 90+ dB dynamic range and temperature compensation as the base SA636 family.

Does SA636DK,118 support internal oscillator operation, or does it require external LO injection?

The SA636DK,118 supports both internal and external oscillator configurations. Its OSC_IN (pin 4) and OSC_OUT (pin 3) pins accept crystal oscillators up to 150 MHz or LC tanks up to 1 GHz. Internal oscillator operation is validated in test circuits with 10.7 MHz IF, while external LO injection (e.g., 120.392 MHz for DECT) is explicitly documented in application schematics. The SA636DK,118 retains full mixer conversion gain (11 dB) and noise figure (12 dB) in either mode.

What is the recommended decoupling strategy for SA636DK,118's RF and IF sections?

SA636DK,118 requires dedicated decoupling per functional block: RF_IN_DECOUPL (pin 2) with 1 nF capacitor, two LIMITER_DECOUPL pins (12,13) each with 1 nF, IF_AMP_DECOUPL pins (17,19) each with 1 nF, and VCC (pin 5) with 100 nF + 15 µF parallel capacitance. This multi-capacitor approach suppresses supply noise across RF, IF, and limiter stages, preventing instability and ensuring specified 54 dB limiter gain and 12 dB mixer NF in the SA636DK,118.

How does the POWER_DOWN_CTRL pin function in SA636DK,118, and what is its logic polarity?

The POWER_DOWN_CTRL pin (pin 8) of SA636DK,118 is active HIGH: driving it LOW places the device in standby mode with ICC = 200 µA, while driving it HIGH enables normal operation with ICC = 6.5 mA typical at 3 V. Input thresholds are CMOS/TTL-compatible (VI(H) ≥ 0.7 × VCC, VI(L) ≤ 0.3 × VCC), and input current is ±10 µA across temperature. This controlled shutdown capability is integral to the SA636DK,118's low-power design for battery-operated receivers.

Can SA636DK,118 directly drive a 10.7 MHz ceramic filter without external impedance matching?

Yes, SA636DK,118 is designed for direct interface with 10.7 MHz ceramic filters. Its MIXER_OUT (pin 20) has an internal 330 Ω termination, and both IF_AMP_IN (pin 18) and LIMITER_IN (pin 14) present 330 Ω input impedance. This matches standard 330 Ω ceramic filters (e.g., Murata SFE10.7MA5-A), eliminating external matching networks and reducing component count-a key feature confirmed in SA636DK,118 application circuits and datasheet Table 9.