NXP Semiconductors MC33493MOD315EV

Overview

MC33493MOD315EV from Freescale Semiconductor is a PLL-tuned UHF transmitter IC designed for low-power wireless data transfer in 315 MHz band applications. It supports OOK/FSK modulation, operates from 1.9–3.6 V, delivers up to +5 dBm RF output power with 50 Ω matching, and draws only 0.1 nA standby current at 25 °C - enabling single-cell lithium battery operation in keyfobs and remote controls.

For engineers reviewing the MC33493MOD315EV datasheet, MC33493MOD315EV pinout, MC33493MOD315EV application, or MC33493MOD315EV equivalent, this device serves as a fully integrated, temperature-stable (–40 to 125 °C), ETSI-compliant transmitter requiring minimal external components - ideal for automotive keyless entry, industrial telemetry, and secure access systems where low quiescent current and fast PLL lock-in (<1.6 ms) are critical.

Technical Context

The MC33493MOD315EV integrates a relaxation-type VCO, phase-frequency detector (PFD), and loop filter into a single PLL architecture. Its output frequency is derived as f_RFOUT = f_XTAL × PLL divider ratio - 32 for 315 MHz using a 9.84 MHz crystal. Band selection is controlled by the BAND pin, and modulation type (OOK or FSK) is set via the MODE pin.

FSK is implemented via crystal pulling using an internal switch on CFSK, with deviation determined by total load capacitance (C3/C4 + parasitics). OOK enables direct DATA-driven RF enable/disable switching. The state machine enforces strict sequencing: standby → PLL acquisition → locked transmission, with automatic RF disable on loss of lock or supply shutdown below 1.56–2.11 V.

Key Specifications

Pinout & Package

TSSOP-14 package (Case 948G-01), 5.0 × 4.4 × 1.2 mm, lead-free (RoHS-compliant), thermal pad not electrically connected.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar UHF transmitter applications.

Compared with MAX1479EEE+ and SI4010-C2-GM, the MC33493MOD315EV uniquely combines sub-nanoampere standby, integrated DATACLK, and crystal-pulling FSK - making it optimal for cost-sensitive, long-life, timing-critical 315 MHz keyfob designs where external clocking or EEPROM is unnecessary.

Availability

MC33493MOD315EV is available at Aetrix Electronics and suitable for automotive keyless entry, industrial telemetry, and secure access control systems requiring stable component supply and long-term lifecycle support.

Supply support for MC33493MOD315EV 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

Freescale Semiconductor (now part of NXP Semiconductors) is a global leader in automotive, industrial, and networking semiconductors, known for high-reliability analog and mixed-signal ICs.

The MC33493 product line was engineered specifically for battery-operated UHF remote controls and keyless entry systems - prioritizing ultra-low power, ETSI compliance, and minimal external component count.

FAQ

What frequency bands does the MC33493MOD315EV support, and how is band selection configured?

The MC33493MOD315EV supports 315 MHz and 434 MHz bands (high BAND pin) or 868–928 MHz (low BAND pin). For MC33493MOD315EV, the "MOD315" suffix confirms factory configuration for 315 MHz operation using a 9.84 MHz crystal and PLL divider ratio 32. Band selection is hardwired via the BAND pin voltage level during power-up.

How does the MC33493MOD315EV achieve FSK modulation without external varactors or DACs?

The MC33493MOD315EV implements FSK via crystal pulling: the CFSK pin drives an internal NMOS switch that toggles external load capacitors (C3/C4), changing the crystal's effective load capacitance and thus its oscillation frequency. This shifts the PLL output by ±100 kHz at 315 MHz - all without varactors, DACs, or additional ICs.

What is the purpose of the dual VCC pins (pins 9 and 12) on the MC33493MOD315EV?

The MC33493MOD315EV features two independent VCC pins (9 and 12) to reduce power supply impedance and isolate noise coupling between analog/RF and digital sections. Each requires dedicated 22 nF + 100 pF decoupling; separating supply paths improves RF spectral purity and prevents digital switching noise from modulating the carrier.

Can the MC33493MOD315EV operate from a single 1.9 V lithium coin cell, and what happens below that voltage?

Yes, the MC33493MOD315EV operates down to 1.9 V and includes a programmable shutdown threshold (1.56–2.11 V depending on temperature). Below this threshold, the entire circuit latches off - including PLL and RF stages - preventing erratic transmission. Recovery requires a low pulse on ENABLE, ensuring clean restart after brownout.

What is the function of the DATACLK pin on the MC33493MOD315EV, and how is its frequency determined?

The DATACLK pin on the MC33493MOD315EV outputs a divided-down version of the crystal reference (f_XTAL/64), providing a precise 154 kHz clock for MCU data framing. For MC33493MOD315EV's 9.84 MHz crystal, DATACLK = 154 kHz - enabling Manchester encoding synchronization without external timing components.