X90100 Datasheet, PDF (5/7 Pages) Xicor Inc. – NV Electronically Programmable Capacitor

X90100
Power Up Timing (Digital Inputs Floating, Internal Pullup Action Shown)
V_CC = 3.3 or 5.0V
V_CC
t_RV_CC
CS
INC
U/D
Power Up and Down Requirements
There are no restrictions on the power-up or power-down
conditions of V_CC and the voltages applied to the Cp, Cm
pins provided that V_CC is always more positive than or equal
to V_Cp, V_Cm, i.e., V_CC ≥ V_Cp, V_Cm. The V_CC ramp rate spec
is always in effect.
Powerup Requirements
In order to prevent unwanted tap position changes or an
inadvertant store, bring the CS and INC high before or
concurrently with the V_CC pin. The logic inputs have internal
active pullups to provide reliable powerup operation. See
powerup timing diagram.
Pin Configuration
MSOP
INC
U/D
Vss
Cp
1
8
2
7
X90100
3
6
4
5
V_CC
CS
N/C (leave floating)
Cm
Detailed Pin Descriptions
Cp and Cm
The high (Cp) and low (Cm) terminals of the X90100 are
equivalent to the fixed terminals of a mechanical trimmable
capacitor. The minimum dc voltage is V_SS and the maximum
is V_CC. The value of capacitance across the terminals is
determined by digital inputs INC, U/D, and CS.
Up/Down (U/D)
The U/D input controls the direction of the trimmed capacitor
value and whether the counter is incremented or
decremented. This pin has an active current source pullup.
5
Increment (INC)
The INC input is negative-edge triggered. Toggling INC will
move the capacitance value and either increment or
decrement the counter in the direction indicated by the logic
level on the U/D input. This pin has an active current source
pullup.
Chip Select (CS)
The device is selected when the CS input is LOW. The
current counter value is stored in nonvolatile memory when
CS is returned HIGH while the INC input is also HIGH. After
the store operation is complete the X90100 will be placed in
the low power standby mode until the device is selected
once again. This pin has active circuit source pullup.
N/C - This pin should be left floating.
Pin Names
SYMBOL
DEFAULT
Cp
output
Cm
output
VSS
VCC
U/D
supply
supply
pull up
INC
pull up
CS
pull up
DESCRIPTION
Positive capacitor terminal
Negative capacitor terminal
Ground
Positive supply voltage
Up/Down control input
Increment control input
Chip Select control input
Principles of Operation
There are three sections of the X90100: the input control,
counter and decode section; the nonvolatile memory; and
the capacitor array. The input control section operates just
like an up/down counter. The output of this counter is
decoded to turn on electronic switches connecting internal
units to the sum capacitor. Under the proper conditions the
contents of the counter can be stored in nonvolatile memory
FN8156.0
February 2, 2005