1. General Description
ISSC IS1685S is a compact, high integration, ultra-low cost, CMOS single-chip RF +
baseband IC for Bluetooth v3.0(EDR) (Enhanced Data Rate) 2.4GHz applications. This
chip is fully compliant with Bluetooth specification and completely backward-compatible
with Bluetooth 1.1, 1.2, 2.0 or 2.1 systems.
It incorporates Bluetooth 1M/2M/3Mbps RF, single-cycle 8051, TX/RX modem, memory
controller, task/hopping controller, UART interface, and ISSC Bluetooth software stack to
achieve the required Bluetooth v3.0(EDR) functions.
The IS1685S is designed to support high quality voice application, an audio engine and a
high performance mono CODEC are integrated for this purpose.
The audio engine provides the A-law/μ-law/CVSD encoding/decoding and also the
enhanced noise reduction and echo supression to offer the best voice quality in the both
sending and receiving sides.
In addition, to minimize the external components required for portable devices, a power
manager unit including the Li-ion battery charger, a switching regulator and LDOs are
integrated to reduce BOM cost for various Bluetooth applications.
The device incorporates built-in self-test (BIST) and auto-calibration functions to simplify
production test.

2. Features
System Specification
 Compliant with Bluetooth Specification v.3.0 (EDR) in 2.4 GHz ISM band
Baseband Hardware
 16MHz main clock input
 Built-in internal ROM for program memory
 Built-in 32 KB RAM for data storage and baseband data transfer buffering
 Bluetooth 2.1 Secure Simple Pairing
 Support both Pico-net and Scatter-net applications
 Hard-wired logic for modulation, demodulation, access code correlation, whitening,
forward error correction (FEC), header error check (HEC), shorten hamming code,
CRC generation/checking, frame check sequence (FCS), encryption bit stream
generation, and transmit pulse shaping
 Adaptive Frequency Hopping (AFH) avoids occupied RF channels
 Fast Connection supported
RF Hardware
 Fully Bluetooth 3.0 (EDR) system in 2.4 GHz ISM band.
 Combined TX/RX RF terminal simplifies external matching and reduces external
antenna switches.
 Max. +4dBm output power with 20 dB level control from register control.
 Build-in T/R switch for Class 2/3 application
 Build-in channel filter.
 To avoid temperature variation, temperature sensor with temperature calibration is
utilized into bias current and gain control.
 Fully integrated synthesizer has been created. There requires no external VCO,
varactor diode, resonator and loop filter.
 Crystal oscillation with build-in digital trimming for temperature/process variations.
Audio processor
 Support 64 kb/s A-Law or -Law PCM format, or CVSD (Continuous Variable Slope
Delta Modulation) for SCO channel operation.
 Noise suppression
 Echo suppression
 SBC decoding
 Packet/Bit error concealment
Audio Codec
 16 bit mono codec
 94dB SNR DAC playback
 Integrate headphone amplifier for 16Ω speakers
Peripherals
 Built-in Lithium-ion battery charger
 Integrate 3V, 1.8V LDO and Switching mode regulator
 Built-in 10-bit Aux-ADC for battery monitor and voltage sense.
 LED driver
Flexible HCI interface
 High speed HCI-UART (Universal Asynchronous Receiver Transmitter) interface
Package
 7x7mm2 48QFN standard package