CY27EE16ZE
Document #: 38-07440 Rev. *C
Page 2 of 17
Functional Description
The CY27EE16ZE integrates a 16-kbit EEPROM scratchpad
and a clock generator that features Cypress’s programmable
clock core. An industry standard I2C serial programming
interface (SPI) is used to program the scratchpad and clock
core.
16-kbit EEPROM
The 16-kbit EEPROM scratchpad is organized in eight blocks
x 256 words x 8 bits. Each of the eight 2-kbit EEPROM
scratchpad blocks, a 2-kbit clock configuration EEPROM
block, and a 2-kbit volatile clock configuration SRAM block,
have their own 7-bit device address. The device address is
combined with a Read/Write bit as the LSB and is sent after
each start bit.
Clock Features
The programmable clock core is configured with the following
features:
• Crystal Oscillator: Programmable drive and load, support
for external references up to 166 MHz. See "Reference
Frequency (REF)", page 5
• VCXO: Analog or digital control
• Inputs and I/Os: Programmable input muxes drive write
protect (WP), analog VCXO control, output enable (OE),
and power down mode (PDM) functions
• PLL: Programmable P, Q, offset, and loop filter parameters.
Outputs: Six outputs and two programmable linear dividers.
The output swing of CLOCK1 through CLOCK4 is set by VDDL
(2.5V or 3.3V). The output swing of CLOCK5 and CLOCK6 is
set by VDD (3.3V).
Clock configuration is stored in a dedicated 2-kbit block of
nonvolatile EEPROM and a 2-kbit block of volatile SRAM. The
SPI is used to write new configuration data to the on-chip
programmable registers that are defined within the clock
configuration memory blocks. Other, custom configurations,
that include custom VCXO, Spread Spectrum for EMI
reduction, Fractional N and frequency select pins (FS) are
programmable; contact factory for details.
Write Protect (WP) – Active HIGH
The default clock configuration of the CY27EE16ZE has pin
17 configured as WP. When a logical HIGH level input is
asserted on this pin, the write protect feature (WP) will inhibit
writing to the EEPROM. This protects EEPROM bits from
being changed, while allowing full read access to EEPROM.
Writing to SRAM is allowed with WP enabled. When this pin is
held at a logical LOW level, WP is disabled and data can be
written to EEPROM.
Analog Adjust for Voltage Controlled Crystal Oscillator
(VCXO)
Pin 17 can be programmed, with the SPI, to function as the
analog control for the VCXO. Then, pin 17 provides ±150 ppm
adjustment of the crystal oscillator frequency (in order to use
the VCXO, the crystal must have a minimum of ±150 ppm pull
range and meet the pullable crystal specifications as shown in
Table 14 on page 12). The crystal oscillator frequency is pulled
lower by at least 150 ppm when 0V is applied to VCXO, pulled
higher by at least 150 ppm when VDD is applied to VCXO. The
oscillator frequency will have a linear dependence on the
voltage level applied to pin 17, VCXO, within a range from 0V
to VDD. See section "Device Addressing", page 10 for more
information.
Note:
1. Float XOUT if XIN is externally driven.
Pin Description
Name
Pin Number
Description
XIN
1
Reference crystal input
VDD
2, 19
3.3V voltage supply
CLOCK6
3
Clock output 6
AVDD
4
3.3V analog voltage supply
SDAT
5
Data input for serial programming
AVSS
6
Analog ground
VSSL
7
Output ground
CLOCK1
8
Clock output 1
CLOCK2
9
Clock output 2
OE/PDM
10
Output enable or power-down mode enable
VDDL
11,14
Output voltage supply
CLOCK3
12
Clock output 3
SCL
13
Clock signal input for serial programming
CLOCK4
15
Clock output 4
VSS
16
Ground
VCXO/WP
17
Analog control input for VCXO or write protect (user-configurable)
CLOCK5
18
Clock output 5
XOUT[1]
20
Reference crystal output
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