SSTX4915

SSTX4915 SST | Alldatasheet

Document overview

• Manufacturer or author: Silicon Standard Corp.
• PDF pages: 9

Technical content

Features

Output frequency range: 100 – 960 MHz Supply voltage range: 2.2 – 3.6 V Low current consumption with power down capability On-chip VCO with integrated PLL (÷ 64/128) dual modulus prescaler Out-of-lock inhibit circuit SSOP-16 package (0.64 mm pitch)

Applications

Car alarm and home security systems Remote control systems Block Diagram TXEN OSC OUT OSC IN NC VSS2 VCC2 RES RES OSC VCO Prescaler ÷ 64/128 DO PFD and CP VSS TXOUT VSS1 VCC1 MODIN AMP LD SW LD BIAS SSTX4915 Preliminary

www.SiliconStandard.com 2 of 9 SSTX4915 Pin Descriptions Rev.2.02 8/06/2003 Number Name

Description

This pin is connected directly to the base of the reference oscillator transistor. The reference oscillator uses a modified Colpitts configuration. OSCOUT This pin is connected directly to the emitter of the reference oscillator transistor. TXEN Transmitter enable control (TXEN = low = power down mode; TXEN = high = normal operation mode). VSS Ground connection for the transmit output amplifier. TXOUT Transmitter output. This pin is an open collector and requires a pull-up inductor for bias/matching and a tapped capacitor for matching. VSS1 Ground connection for the transmit driver amplifier. VCC1 Nominal supply voltage for the transmit driver amplifier. MODIN ASK modulation input. An external resistor RMODIN to supply voltage is used to bias the entire transmit amplifier chain through this pin. VCC2 Nominal supply voltage for the VCO and PLL circuitry. VSS2 Ground connection for the PLL circuitry. NC No connection. RES Differential open collector VCO outputs. RES DO Output of the charge pump. An R-C network from this pin to ground is used to establish the PLL bandwidth. LD Lock detector output. This pin is used to set the threshold of the lock detect circuitry which enables or disables the transmit amplifier. A shunt capacitor should be used to set an R-C time constant with the on-chip series 1kΩ resistor. The time constant should be set to approximately 15 times the reference period. SW Prescaler modulus control input (SW = high = ÷ 64; SW = low = ÷ 128). OSCIN OSCOUT TXEN VSS TXOUT VSS1 VCC1 MODIN SW LD DO RES RESB VREFP VSS2 VCC2 SSTX4915

Rev.2.02 8/06/2003 www.SiliconStandard.com 3 of 9 Absolute Maximum Ratings VSS, VSS1, VSS2 = 0V Recommended Operating Conditions VSS, VSS1, VSS2 = 0V Parameter Rating Unit Supply voltage range –0.3 to +3.6 V Power-down voltage –0.3 to VCC V MODIN voltage –0.3 to +1.1 V Operating ambient temperature –40 to +85 Storage temperature –40 to +150 Parameter Symbol Value Unit min. typ. max. Supply voltage range VCC 2.2 3.0 3.6 V Operating temperature TA –10 +25 +60 oC

www.SiliconStandard.com 4 of 9 SSTX4915 Rev.2.02 8/06/2003

Electrical Characteristics

(VCC = 3V, VSS, VSS1, VSS2 = 0V, TXEN = high, TA = 25°C, and fRF = 433.92MHz unless otherwise noted) Parameter Symbol Condition Value Unit min. typ. max. Power supply Supply voltage VCC 2.2 3.0 3.6 V Total DC current (normal operation) ICC 50% duty cycle, 10kHz data applied to the MODIN pin (RMODIN = 10kΩ) 10.5 mA Total DC current (power-down mode) Istandby TXEN = low µA Overall RF input frequency range fRF 100 960 MHz Modulation ASK Modulation frequency fMOD 100 kHz Output power POUT 50 Ω load dBm ON/OFF ratio dB PLL Prescaler divide ratio SW = high = ÷64 SW = low = ÷128 128 VCO gain KVCO Frequency and board layout dependent MHz/V Phase noise

10 KHz offset, 50 KHz loop BW

–80 dBc/Hz

100 KHz offset, 50 KHz loop BW

–90 dBc/Hz 2nd harmonic –30 dBc 3rd harmonic –40 dBc Reference frequency MHz Crystal frequency spurs

50 KHz PLL loop BW

–50 dBc Charge pump current ICP -100 100 µA Stand-by mode control Transmitter enable/disable voltage TXEN = high = normal operation Vcc – 0.3 V V TXEN = low = power-down mode 0.3 V Turn-on time ms Turn-off time ms

www.SiliconStandard.com 5 of 9 SSTX4915 Functional Description Rev.2.02 8/06/2003 The SSTX4915 is a low-power ASK transmitter IC designed for applications operating within the frequency range of 100 to 960 MHz. In particular, it is intended for transmitter applications in 315/433 MHz band remote keyless entry and 868/915 MHz ISM-band systems. In addition, the SSTX4915 possesses a PLL-only mode which allows it to be simply used as a local oscillator source. The integrated voltage-controlled oscil- lator (VCO), phase/frequency detector, prescaler, and reference oscillator require only the addition of an external crystal to provide a complete phase-locked loop. In addition to the normal operation mode, the chip also includes an automatic lock-detect feature that disables the transmitter output when the PLL is out- of-lock. Reference crystal oscillator The OSCIN and OSCOUT inputs (pins 1 and 2) provide connections to an on-chip transistor which may be used to implement a Colpitts crystal oscillator. The Colpitts oscillator configuration is a low parts count topology which achieves reasonable phase noise performance. Optionally, an external signal may be ac- coupled into the OSCIN pin to provide a reference source. The OSCIN input drive level should be near 500 mVpk-pk to prevent overdriving the on-chip transistor in order to keep the phase noise and reference spurs to a minimum. Voltage controlled oscillator The VCO uses a tuned differential amplifier topology with the bases and collectors cross-coupled to pro- vide positive feedback and the necessary 360° phase shift. A tuned circuit is connected to the open collec- tor outputs and is comprised of both on-chip varactors and user-selectable off-chip inductors. The choice of inductor values determines the frequency band of operation. Dual-modulus prescaler A series of flip-flops divides the VCO frequency by either 64 or 128, depending upon the logic level of the SW input (pin 16). SW = high will select the ÷ 64 mode and SW = low will select the ÷ 128 mode. The divided-down signal is then applied to the phase/frequency detector where its phase/frequency is compared with the phase/frequency of the crystal reference. Phase/frequency detector and charge pump The phase/frequency detector (PFD) is implemented using the “tri-state comparator” topology while the charge pump (CP) consists of a current source and sink for charging and discharging the off-chip loop filter. When the VCO and reference inputs to the PFD are both phase- and frequency-locked, the CP output enters a high impedance state. Otherwise, the CP will either charge or discharge the loop filter. Out-of-lock inhibit circuitry The out-of-lock inhibit circuitry is used to disable the transmitter output when the VCO is not locked to the reference oscillator and comply with regulatory limits during the unlocked condition. An off-chip shunt capacitor connected to the LD output (pin 15) is used to set an R-C time constant (together with an on-chip series 1 K. resistor.) This time constant should be set to be approximately 15 times the reference period.

www.SiliconStandard.com 6 of 9 Transmit amplifier chain A transmit amplifier chain consists of a driver amplifier followed by an open collector output stage. The open collector TXOUT output (pin 5) requires an external pull-up inductor for bias. This inductor may be used as part of an L-C matching circuit for transforming the amplifier output impedance to that of an exter- nal loop antenna. To achieve optimum power-added efficiency, the peak-to-peak RF voltage swing at the TXOUT pin should be twice the supply voltage. Also, the output amplifier has its own ground pin (VSS) in order to improve isolation. The transmitter chain is designed for amplitude-shift-keying/on-off keying (ASK/OOK), with the modula- tion data provided at the MODIN input (pin 8). When V MODIN > 0.7 V, an output signal is transmitted, and when V MODIN <0.7 V, no output signal is transmitted. Operation modes The table below summarizes the TX4915’s three operating modes — power-down, PLL-only and transmit, which are controlled by the TXEN and MODIN inputs. TXEN MODIN Operation Mode L L Power-down H L PLL-only H > 0.7 V Transmit Rev.2.02 8/06/2003 SSTX4915

www.SiliconStandard.com 7 of 9 SSTX4915 Application Circuits Rev.2.02 8/06/2003 fRF = 315 MHz fRF = 434 MHz A A B B C C D D E E OSC1 OSC2 TXEN VSS PA OUT VSS1 VCC MOD IN LD DO RESB RES NC VSS2 VCC2 SSTX4915 {Doc} {RevCode} SSTX4915-Z ASK 315MHz B Thursday, June 12, 2003 Title Size Document Number Rev Date: Sheet of VCC_3V VCC VCC 100P 100P 100P 10K 1K8 120nH 4.921 82nH 220P 47P 3P3 1K8 ANT1 ANTENNA 18K 220P 330nH C14 100P C15 10n C16 100P C17 10n C10 220P C12 100P C13 10n 3.3uF 2.2N C11 6P8 C18 10n DATA A A B B C C D D E E OSC1 OSC2 TXEN VSS PA OUT VSS1 VCC MOD IN LD DO RESB RES NC VSS2 VCC2 SSTX4915 {Doc} {RevCode} SSTX4915-Z ASK 434MHz B Thursday, June 19, 2003 Title Size Document Number Rev Date: Sheet of VCC_3V VCC VCC 100P 100P 100P 100K 33nH 6.78 56nH 220P 47P 2P2 ANT1 ANTENNA 10K 220P 330nH C14 100P C15 10n C16 100P C17 10n C10 4P7 C12 100P C13 10n 3.3uF 56P C11 5P6 C18 10n 33nH 100 DATA

www.SiliconStandard.com 8 of 9 SSTX4915 Application Circuits (cont.) Rev.2.02 8/06/2003 fRF = 868 MHz A A B B C C D D E E VSS2 TXEN PA OUT VCC NC VCC2 RESB SSTX4915 OSC1 DO VSS VSS1 OSC2 MOD IN RES LD {Doc} {RevCode} {Title} B Wednesday, June 25, 2003 Title Size Document Number Rev Date: Sheet of VCC_3V VCC VCC C11 0.82P C17 10n 180nH 220P C10 220P 220P 2.2N C16 100P 10K 100P C13 10n 22P C15 10n 6.8nH 100P ANT1 ANTENNA 13.577 C18 10n 3.3uF C12 100P 2.2P 100 C14 100P 100P 3K3 27nH 6.8nH DATA

Information furnished by Silicon Standard Corporation is believed to be accurate and reliable. However, Silicon Standard Corporation makes no guarantee or warranty, express or implied, as to the reliability, accuracy, timeliness or completeness of such information and assumes no responsibility for its use, or for infringement of any patent or other intellectual property rights of third parties that may result from its use. Silicon Standard reserves the right to make changes as it deems necessary to any products described herein for any reason, including without limitation enhancement in reliability, functionality or design. No license is granted, whether expressly or by implication, in relation to the use of any products described herein or to the use of any information provided herein, under any patent or other intellectual property rights of Silicon Standard Corporation or any third parties. www.SiliconStandard.com 9 of 9 Symbol Dimensions in mm Dimensions in inches min. nom. max. min. nom. max. A 1.35 1.60 1.75 0.053 0.064 0.069 0.10 0.25 0.004 0.010 1.45 0.057 b 0.20 0.25 0.30 0.008 0.010 0.012 C 0.19 0.25 0.007 0.010 D 4.80 5.00 0.189 0.197 E 5.80 6.20 0.228 0.244 3.80 4.00 0.150 0.157 e 0.64 0.025 L 0.40 1.27 0.016 0.050 y 0.10 0.004 θ SSTX4915 Package Dimensions Rev.2.02 8/06/2003