cy8c9520a Cypress Semiconductor Corporation., cy8c9520a Datasheet - Page 8

• Manufacturer Part Number: cy8c9520a
• Description: 20-, 40-, And 60-bit Io Expander With Eeprom
• Manufacturer: Cypress Semiconductor Corporation.

PIN Descriptions
Extendable Soft Addressing™
The A0 line defines the corresponding bit of the I2C address.
This pin must be pulled up or down. If A0 is a strong pull up or a
strong pull down (wired through 330 or less resistor to Vdd or
Vss), then that is the only address line being specified and the
A1-A6 lines are used as GPIO. If A0 is a weak pull up or a weak
pull down (connected to Vdd or Vss through 75K- 200K ohm
resistor), then A0 is not the only externally defined address bit.
There is a pin assigned to be A1 if it is needed. This pin can be
pulled up or pulled down strong or weak with a resistor. As with
A0, the type of pull determines whether the address bit is the last
externally defined address bit. Differently from A0, A1 is not
dedicated as an address pin. It is only used if A0 is not the only
address bit externally defined. There are also predefined pins for
A2, A3, A4, A5, and A6 that is only used for addressing if needed.
The last address bit in the chain is pulled strong. That way, only
the number of pins needed to assign the address desired for the
part are allocated as address pins, any pins not used for address
bits can be used as GPIO pins. The
Addressing,” on page 3
Interrupt Pin (INT)
The interrupt output (if enabled) is activated if one of these
events occurs:
■
■
The interrupt line is deactivated when the master device
performs a read from the corresponding Interrupt Status register.
Write Disable Pin (WD)
If this feature is enabled, ‘0’ allows writes to the EEPROM and
‘1’ blocks any memory writes. This pin is checked immediately
before performing any write to memory. If the EEE bit in the
Enable register is not set (EEPROM disabled) or bit EERO is set
(EEPROM is read-only) then WD line level is ignored.
Note that ‘1’ on this line blocks all commands that perform opera-
tions with EEPROM (see
page
This line may be enabled/disabled by bit 1 of the Enable register
(2Dh): ‘1’ enables WD function, ‘0’ disables.
External Reset Pin (XRES)
A full device reset is caused by pulling the XRES pin high. The
XRES pin has an always-on pull down resistor, so it does not
require an external pull down for operation. It can be tied
directly to ground or left open. Behavior after XRES is similar to
POR.
Document Number: 38-12036 Rev. *B
One of the GPIO port pins changes state and the corresponding
bit in the Interrupt Mask register is set low.
When a PWM driven by the slowest clock source (367.6 Hz)
and assigned to a pin changes state and the pin’s corre-
sponding bit in the Interrupt Mask register is set low.
13).
defines the resulting device I2C address.
Table 15, “Available Commands,” on
Table 2, “Device
Working with PWMs
There are four independent PWMs in the CY8C9520A, eight in
the CY8C9540A and sixteen in the CY8C9560A. Each IO pin
can be configured as a PWM output by writing ‘1’ to the corre-
sponding bit of the Select PWM register (see
and Select PWM Registers Logic,” on page
The next step of PWM configuration is clock source selection
using the Config PWM registers. There are six available clock
sources: 32 kHz (default), 24 MHz, 1.5 MHz, 93.75 kHz, 367.6
Hz or previous PWM output. (see
Figure 5. Clock Sources
By default, 32 kHz is selected as the PWM clock.
PWM Period registers are used to set the output period:
Allowed values are between 1 and FFh.
The PWM Pulse Width register sets the duration of the PWM
output pulse. Allowed values are between zero and the
(Period-1) value. The duty cycle ratio is computed using thsi
equation:
t
DutyCycle
OUT
=
Period t
93.75 kHz
1.5 mHz
24 mHz
32 kHz
=
PulseWidth
------------------------------
×
CY8C9520A, CY8C9540A
Period
CLK
Divider (1-255)
Figure
5)
CY8C9560A
11).
367.6 Hz -
93.75 kHz
Table 8, “Output
Page 8 of 24
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