Analog Devices Inc. AD7341JP

Overview

AD7341JP from Analog Devices is a voiceband reconstruction filter IC designed for the transmit path of high-speed CCITT V.32/V.33 modems, implementing a seventh-order switched-capacitor low-pass + second-order continuous-time low-pass architecture with 3.5 kHz cutoff, programmable 0 dB to –38 dB attenuation (6-bit digital control), and 75 dB SNR at 1 kHz. It interfaces directly with 14-bit DACs like the AD7840 in analog front-end signal chains.

For engineers reviewing the AD7341JP datasheet, AD7341JP pinout, AD7341JP application, or AD7341JP equivalent, this device is selected for precise transmit-channel spectral shaping in echo-cancelling modem designs requiring stable group delay, <0.4 dB passband ripple (0–3.3 kHz), and >70 dB stopband rejection above 6.1 kHz.

Technical Context

The AD7341JP uses a dual-stage filtering architecture: a fully differential seventh-order elliptical switched-capacitor low-pass filter (SCF) clocked at 57.6 kHz (derived from 288 kHz CLKIN via ×5 divider), followed by a second-order continuous-time low-pass smoothing stage. Its cutoff frequency is fixed at 3.5 kHz (0.1 dB down point) and exhibits <2% unit-to-unit variation due to capacitor matching.

Digital control includes WR-latched 6-bit attenuation programming (DB2–DB7), asynchronous SYNCIN for SCF clock alignment, and programmable input/output dividers (DPO/DPI, DSO/DS1/DS2) enabling synchronized timing with external DACs - critical for avoiding low-frequency aliasing in 9.6 kHz or 7.2 kHz sampling systems.

Key Specifications

Pinout & Package

AD7341JP is housed in a 28-pin Plastic Leaded Chip Carrier (PLCC) package with gull-wing leads, rated for 0°C to +70°C operation (J-grade). Pin 1 identifier is marked by a notch or dot; thermal pad is not electrically connected.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar voiceband reconstruction filter applications.

Compared with AD7341JN and MAX274ACPP+, the AD7341JP uniquely combines PLCC packaging, integrated 6-bit programmable attenuation, and guaranteed V.32/V.33 compliance - making it the only drop-in solution for production modem AFEs requiring both compact layout and field-updatable line calibration.

Availability

AD7341JP is available at Aetrix Electronics and suitable for voiceband modem design, telecom data pump development, and echo-cancelling AFE integration requiring stable component supply across industrial temperature ranges and long product lifecycles.

Supply support for AD7341JP 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 is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, founded in 1965 and headquartered in Wilmington, MA.

The AD7341JP belongs to Analog Devices' LC2MOS voiceband filter family, engineered specifically for CCITT V.32/V.33 modem analog front-ends - emphasizing low distortion, precise cutoff control, and seamless digital interfacing with 14-bit DACs.

FAQ

What is the primary function of the AD7341JP in a modem system?

The AD7341JP serves as the transmit reconstruction filter in CCITT V.32/V.33 modems, smoothing the stepped output of a 14-bit DAC (e.g., AD7840) into a band-limited analog signal. Its 3.5 kHz cutoff, programmable attenuation, and low group delay ensure compliance with international spectral masks and minimize inter-symbol interference - critical for reliable 14.4 kbps operation. The AD7341JP achieves this using a hybrid switched-capacitor + continuous-time architecture.

How does the AD7341JP achieve synchronization with external DACs?

The AD7341JP generates a synchronized clock on-chip via its SYNCOUT pin, derived from the internal 57.6 kHz switched-capacitor filter clock (fCLKIN/(N1×5×N2)). By configuring DSO/DS1/DS2, users set N2 to produce exact integer multiples of standard DAC update rates (e.g., 9.6 kHz or 7.2 kHz). This eliminates low-frequency aliasing. The SYNCIN pin further enables cycle-slipping for sub-cycle phase alignment - a capability built into the AD7341JP's clock generation circuitry.

What are the supply voltage requirements for the AD7341JP?

The AD7341JP requires three independent supplies: VDD = +5 V (±5%) for analog circuitry, VCC = +5 V (±5%) for digital logic, and VSS = –5 V (±5%) for analog biasing. AGND (Pin 22) and DGND (Pin 7) must be kept separate and tied to their respective supply returns. This triple-supply, split-ground architecture ensures >75 dB SNR and <–80 dB harmonic distortion - key specifications verified in the AD7341JP datasheet under these exact conditions.

Can the AD7341JP be used with clock frequencies other than 288 kHz?

Yes - the AD7341JP supports CLKIN frequencies of 288 kHz, 576 kHz, 864 kHz, or 1.152 MHz via programmable input divider (N1 = 1–4 set by DPO/DPI). Regardless of input frequency, the internal SCF clock remains fixed at 57.6 kHz because the divider always applies a ×5 factor. This flexibility allows system designers to use common clock sources while guaranteeing consistent filter response - a feature explicitly documented for the AD7341JP in Analog Devices' datasheet Rev. A.

What is the significance of the 0.1 dB cutoff definition for the AD7341JP?

The AD7341JP's cutoff frequency is defined as the point where gain drops 0.1 dB from the lowest passband level - not the conventional –3 dB point. This stringent definition ensures minimal amplitude deviation across the entire 0–3.3 kHz voiceband, directly supporting CCITT V.32/V.33 requirements for tone transmission fidelity and signaling accuracy. Measured passband ripple is ≤0.4 dB within this band, confirming the AD7341JP's suitability for high-SNR modem applications.