CTST571QG

CTST571QG Datasheet

CTST571

Part	Datasheet
CTST571QG	CTST571QG (pdf)

Related Parts	Information
CTST571MG	CTST571MG

PDF Datasheet Preview
CTST571 Programmable Capacitive Tuning IC SON8, MLP6  Capacitive Tuning Range of 6.6pF to 37.553pF  0.063pF Minimum Step Size  Continually Programmable with Register or EEPROM Data Storage  May Be Placed in Parallel for Greater Capacitance Values  2.5V to 5.0V Supply Voltage  RoHS compliant Pb Free Packages BLOCK DIAGRAM The CTST571 is a digitally programmed capacitor designed to tune a filter or crystal/SAW based oscillator to a desired center frequency. Through a bank of registers, the capacitance value is set by a serial data stream and if desired, can be permanently stored in the nonvolatile EEPROM memory. The CTST571 is designed to be a labor and cost saving device within the oscillator production process and provide the desired functionality for tunable filter banks. While incorporating very small step sizes 0.063pF , multiple CTST571 devices can also be used in parallel to obtain higher overall capacitance values. The CTST571 is available in an SON8 package 1.5mm x 1.0mm for very small form factor designs. Also available in MLP6. ENGINEERING NOTES Capacitor Structure The CTST571 capacitance value is composed of four parallel capacitors banks, CF is a fixed capacitor value of 6.6pF and CHI, CMID and CLO are variable capacitors of differing ranges and resolutions as seen in Table Capacitors composing CHI, CMID and CLO are set with a binary control word through an 11-bit shift register described in “Programming the CTST571” section. The values of each CHI, CMID and CLO stepping are detailed in the complete Nominal Capacitance Binary Mapping spreadsheet. CTOTAL = CF + CHI + CMID + CLO Table 1 Capacitor Structure Internal Capacitor CF CHI CMID CLO Total Min Value pF Max Value pF Step Size pF North Americas +1-800-757-6686 • International +1-508-435-6831 • Asia +65-655-17551 • Specifications are subject to change without notice. 1 CTST571 Programmable Capacitive Tuning IC SON8, MLP6 CTST571 Functional Mode The CTST571 has two methods for setting the capacitance value on the X1 pin. • Reading the Control Word Directly From the Shift Register In tunable filter applications, reading from the shift register will be desirable as the control word can be constantly varied. New control words can be serially inputted as required to change the capacitance value in real time. Note With a serial data input, the capacitance value during transitions between control words is deterministic upon their differences. The shift register is also useful for testing the capacitance and subsequent oscillator frequency. This mode is active when the CLK pin is left logic high. For the shift register, capacitors are selected when bits are active HIGH. • Reading the Control Word From the Value Contained in the EEPROM If a certain control word needs to be stored, it can be written to the nonvolatile EEPROM memory. This is useful in oscillator applications where it prevents customer adjustment and retains factory programming. This mode is active when the CLK pin is at logic low or not connected. For the EEPROM, capacitors are selected when bits are active LOW. Oscillator Application In oscillator applications, the CTST571 is designed to be used in 2 modes, Programming and Operational. In the Programming mode, the CTST571 is used by the manufacturer to set the capacitance value to control the desired center frequency of the oscillator. The programming phase gives the manufacturer access to pins DA, CLK, and PV where the shift registers are used to first determine the required control word. That control word is then stored in the EEPROM memory. CTS can provide this board CTS10EL89 along with software that works through all the programming steps/functions described in the next sections Figure In the Operational mode, the EEPROM internal to the CTST571 has already been programmed with the desired factory settings. Pins DA, CLK, and PV are to be disconnected, thereby allowing the CTST571’s internal pull-downs to place the pins at ground potential. In the operational mode, only 3 pins are necessary for hookup Figure North Americas +1-800-757-6686 • International +1-508-435-6831 • Asia +65-655-17551 • Specifications are subject to change without notice. 2 CTST571 Programmable Capacitive Tuning IC SON8, MLP6 CTS10EL89 CTST571 Figure 1 CTST571 in Programming Mode CTST571 PART ORDERING INFORMATION Part Number CTST571QG CTST571MG Package SON8 MLP6 Marking Y YM Y1G / YM North Americas +1-800-757-6686 • International +1-508-435-6831 • Asia +65-655-17551 • Specifications are subject to change without notice. 13

PDF Datasheet Preview

CTST571

Programmable Capacitive Tuning IC

SON8, MLP6
 Capacitive Tuning Range of 6.6pF to 37.553pF
 0.063pF Minimum Step Size  Continually Programmable with Register
or EEPROM Data Storage  May Be Placed in Parallel for Greater

Capacitance Values  2.5V to 5.0V Supply Voltage  RoHS compliant Pb Free Packages

BLOCK DIAGRAM

The CTST571 is a digitally programmed capacitor designed to tune a filter or crystal/SAW based oscillator to a desired center frequency. Through a bank of registers, the capacitance value is set by a serial data stream and if desired, can be permanently stored in the nonvolatile EEPROM memory. The CTST571 is designed to be a labor and cost saving device within the oscillator production process and provide the desired functionality for tunable filter banks.

While incorporating very small step sizes 0.063pF , multiple CTST571 devices can also be used in parallel to obtain higher overall capacitance values.

The CTST571 is available in an SON8 package 1.5mm x 1.0mm for very small form factor designs. Also available in MLP6.

ENGINEERING NOTES

Capacitor Structure The CTST571 capacitance value is composed of four parallel capacitors banks, CF is a fixed capacitor value of 6.6pF and CHI, CMID and CLO are variable capacitors of differing ranges and resolutions as seen in Table Capacitors composing CHI, CMID and CLO are set with a binary control word through an 11-bit shift register described in “Programming the CTST571” section. The values of each CHI, CMID and CLO stepping are detailed in the complete Nominal Capacitance Binary Mapping spreadsheet.

CTOTAL = CF + CHI + CMID + CLO

Table 1 Capacitor Structure

Internal Capacitor

CF CHI CMID CLO

Total

Min Value pF

Max Value pF

Step Size pF

North Americas +1-800-757-6686
• International +1-508-435-6831
• Asia +65-655-17551
•

Specifications are subject to change without notice. 1

CTST571

Programmable Capacitive Tuning IC

SON8, MLP6

CTST571 Functional Mode

The CTST571 has two methods for setting the capacitance value on the X1 pin.
• Reading the Control Word Directly From the Shift Register In tunable filter applications, reading from the shift register will be desirable as the control word can be constantly varied. New control words can be serially inputted as required to change the capacitance value in real time. Note With a serial data input, the capacitance value during transitions between control words is deterministic upon their differences. The shift register is also useful for testing the capacitance and subsequent oscillator frequency. This mode is active when the CLK pin is left logic high. For the shift register, capacitors are selected when bits are active HIGH.
• Reading the Control Word From the Value Contained in the EEPROM If a certain control word needs to be stored, it can be written to the nonvolatile EEPROM memory. This is useful in oscillator applications where it prevents customer adjustment and retains factory programming. This mode is active when the CLK pin is at logic low or not connected. For the EEPROM, capacitors are selected when bits are active LOW.

Oscillator Application In oscillator applications, the CTST571 is designed to be used in 2 modes, Programming and Operational.

In the Programming mode, the CTST571 is used by the manufacturer to set the capacitance value to control the desired center frequency of the oscillator. The programming phase gives the manufacturer access to pins DA, CLK, and PV where the shift registers are used to first determine the required control word. That control word is then stored in the EEPROM memory. CTS can provide this board CTS10EL89 along with software that works through all the programming steps/functions described in the next sections Figure

In the Operational mode, the EEPROM internal to the CTST571 has already been programmed with the desired factory settings. Pins DA, CLK, and PV are to be disconnected, thereby allowing the CTST571’s internal pull-downs to place the pins at ground potential. In the operational mode, only 3 pins are necessary for hookup Figure

North Americas +1-800-757-6686
• International +1-508-435-6831
• Asia +65-655-17551
•

Specifications are subject to change without notice. 2

CTST571

Programmable Capacitive Tuning IC

SON8, MLP6

CTS10EL89

CTST571

Figure 1 CTST571 in Programming Mode CTST571
PART ORDERING INFORMATION

Part Number CTST571QG CTST571MG

Package SON8 MLP6

Marking Y YM

Y1G / YM

North Americas +1-800-757-6686
• International +1-508-435-6831
• Asia +65-655-17551
•

Specifications are subject to change without notice. 13

Notice: we do not provide any warranties that information, datasheets, application notes, circuit diagrams, or software stored on this website are up-to-date or error free. The archived CTST571QG Datasheet file may be downloaded here without warranties.

Datasheet ID: CTST571QG 507363