NSC NM95HS01M8 Hisec-tm high security rolling code generator Datasheet

NM95HS01/NM95HS02
HiSeC TM High Security Rolling Code Generator
General Description
Features
The NM95HS01/02 HiSeC Rolling Code Generator is a
small footprint, monolithic CMOS device designed to provide a complete, low-cost, high security solution to the problem of generating encrypted signals for remote keyless entry (RKE) applications.
The NM95HS01/02 generates a fully encoded bit stream
each time one of (up to) 4 switch inputs is activated. The
patented* coding scheme utilizes 248 possible user-programmable coding combinations, and features high linear
complexity and correlation immunity. High security is guaranteed by generating a unique (rolling) code for each transmission, and can be further enhanced by creating customized algorithms for individual customers. With this product,
each key can be designed to be both unique and highly
secure.
The NM95HS01/02 supports either an IR or RF signal
transmitter, and can be clocked with either an RC clock
(NM95HS01) or a crystal oscillator (NM95HS02). The device operates over a voltage range of 2.2V to 6.5V, and
offers a low power standby mode (k1 mA) for battery applications. The product is available in both 8-pin and 14-pin SO
packages with 2 or 4 key switch inputs that can be used for
customer presets such as seat positions, and vehicle operating functions such as car door locking/unlocking.
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
High security coding scheme with 248 combinations
High linear complexity and correlation immunity
2.2V to 6.5V operation
Less than 1 mA standby current
Full resynchronization capability
Unique customized algorithm option
13 bytes on-chip non-volatile configuration memory
RC or XTAL clock options for to 4.1 MHz operation
Supports both IR and RF signal transmission
Selection of bit coding and transmission frame formats
Space saving narrow body SO8 or SO14 packages
Up to 4 key switch inputs on SO14 package
Applications
Y
Y
Y
Y
Remote Keyless Entry (RKE) applications
Burglar alarms/garage door openers
Individualized recognition/transmission systems
Personalized consumer automotive applications
Relevant Documents
Y
Y
Y
MM57HS01 datasheet
Designing and Programming a Complete HiSeCTM based RKE System
AN-985
HiSeC Remote Keyless Entry Solution Encoder/Decoder Chip Set User’s Manual
AN-355
*Patents Pending
Functional Block Diagram
TL/D/12302 – 1
Note: Signals shown are internal logic signals.
FIGURE 1
HiSeCTM and MICROWIRETM are trademarks of National Semiconductor Corporation.
C1996 National Semiconductor Corporation
TL/D/12302
RRD-B30M66/Printed in U. S. A.
NM95HS01/NM95HS02 HiSeC High Security Rolling Code Generator
February 1996
The 24-bit key ID register can be used to configure a large
number of unique keys, each of which will produce a unique
encoded output bit stream. The 24 bits in the code generator block are mixed with coded data.
General Characteristics
The NM95HS01/02HiSeC Generator was developed to
meet existing standards for rolling code-based security systems.
The output of this block is then fed into the 24-/36-bit buffer
register, where the 40 bits are recombined to produce a 24or 36-bit output (a user option). The 8-bit sync field register
can be configured by the user to provide a pattern to facilitate synchronization between the transmitter and receiver.
The details of the code block are available to customers,
and exclusive algorithms are available and under contract
with National. Call your local sales office for details.
The HiSeC Generator is shipped with a standard algorithm
as a standard product, with the configuration shown.
Theft prevention systems typically involve user identification
and transmission of information at various distances from
the vehicle. These Remote Keyless Entry (RKE) systems
are generally implemented with IR transmitters for short distances, or RF transmitters for longer distances. RF transmission has become state of the art; however the longer
distances involved require a much higher degree of security,
since the possibility of signal interception is greatly increased.
These applications are ideally served by the
NM95HS01/02. This generator is a small footprint, low current solution that supports both IR and RF transmission.
The device is available in an 8-pin SO package with 2 key
switch inputs, or a 14-pin SO package with 4 key switch
inputs.
The proprietary coding scheme used generates a rolling
code based on 248 possible user combinations, and ensures a high level of coding security for any RKE application. The NM95HS01 can be clocked with an RC circuit,
while the NM95HS02 can be clocked with a crystal oscillator.
Figure 2 shows a general operational block diagram of the
NM95HS01/02 HiSeC Generator. The 4 key switch inputs
shown use internal pull-up resistors, and are suitable for
normally open, single pole input switches connected to
ground. The inputs are buffered by debounce logic which
repeatedly polls the inputs to determine if a key switch has
been asserted. If any key switch input is seen as low for four
continuous 10 ms samples, its associated output is set high,
the HiSeC control logic is activated, and a security code is
generated and transmitted.
The timer block is used to set the key debounce time and
the IR or RF clock times. These clock times are used as the
time base for the chosen bit coding format. The timer block
is also used to generate the interframe pause time, and the
timeout delay, if these are enabled. These parameters are
configured by the user in the 13-byte on-chip EEPROM array.
The NM95HS01 version of the device uses an RC network
to clock the CKI input pin. The CKO/LED pin is not required
for clocking, but may be used for a visual indicator LED. If
the NM95HS02 crystal oscillator version is used, the device
is clocked using both the CKI and CKO pins. If an LED is
used with this device, it may be grounded through the
RFEN/LED pin. Either the CKO/LED or the RFEN/LED output pins can provide the sink current needed to drive an
indicator LED. The RFEN pin is active low during signal
transmission, and is used to provide power to the RF circuit
only during transmission to increase battery life.
The transmit output (TX) pin is a configurable logic level
output, and is used to transmit the encoded bit stream. An
on-chip power-on reset circuit is used to initialize the device
during power-up.
General Device Operation
The Functional Block Diagram (Figure 1) shows the internal
elements of the code generating logic and program registers.
The NM95HS01/02 HiSeC Generator achieves its high security level by combining the contents of several dynamic
data registers in a non-linear manner to generate an encoded output. Data in the registers is comprised of a mixture of
user programmable data, factory programmable data, and
randomized data. This inherently random and separate data
is encrypted by clocking it through a non-linear logic block,
and feeding part of the output back to produce a final coded
output with a high degree of linear complexity and correlation immunity.
The NM95HS01/02 incorporates 13 bytes of non-volatile
EEPROM memory which can be used to configure the device registers. This memory is accessible to the user, and
can be configured to the desired configuration, then writedisabled to prevent tampering.
User programmable data includes 24 bits of the code block,
a 24-bit key ID register, and an 8-bit sync field register.
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Connection Diagrams
8-Pin SO Package (M8)
Pin Names
Pin
Description
KEYn
Key Input
RFEN/LED
RF Enable/LED
CKO/LED
XTAL Clock/LED
TX
Data Transmit
Top View
CKI
RC Clock Input
See NS Package Number
M08A (M8) or N08E (N)
GND
Ground
VCC
Supply Voltage
TL/D/12302–4
14-Pin SO Package (M14) and
14-Pin Dual-In-Line Package (N14)
14-Pin TSSOP Package (MT14)
TL/D/12302 – 5
Top View
See NS Package Number
M14A (M), MTC14 (MT14)
or N14A (N14)
Ordering Information
Commercial Temperature Range (0§ C to a 70§ C)
Order Number
NM95HS01M8/NM95HS02M8
NM95HS01N/NM95HS02N
NM95HS01M/NM95HS02M
NM95HS01MT14/NM95HS02MT14
NM95HS01N14/NM95HS02N14
Extended Temperature Range (b40§ C to a 85§ C)
Order Number
NM95HS01EM8/NM95HS02EM8
NM95HS01EN/NM95HS02EN
NM95HS01EM/NM95HS02EM
NM95HS01EN14/NM95HS02EN14
TL/D/12302 – 2
*Note: Keys 3 and 4 available in 14-pin packages.
FlGURE 2. Operational Block Diagram of the NM95HS01/02 HiSeC Generator
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General Transmitter Circuit
Configurations
Figure 3 shows several typical circuit configurations for a
HiSeC based RKE system transmitter. Note that all circuits
require few external components beyond a battery and
transmitter stage. IR and RF bit timing may be optimized
through the timer block settings in the EEPR0M array, which
allows flexibility in selecting the smallest and least expensive clock components in the chosen design range.
The first two circuits are examples of RF transmitter applications, with both RC and crystal (XTAL) oscillator clocks; the
third circuit is an example of an IR transmitter application.
Two circuits are configured for an LED. Note that the LED
pin refers to a visual indicator LED, and not the IR LED
which might be used in an IR transmitter circuit.
The LEDSEL bit in the EEPROM array determines whether
the RFEN/LED or CKO/LED pins are dedicated to the LED
for a particular circuit configuration. LED pin select options
are detailed in Table I.
Design considerations for selecting and optimizing clock
component values are detailed in the Generator Clock Design Parameters section.
General Receiver Circuit
Configurations
The NM95HS01/02 HiSeC Generator with the standard
customer algorithm is matched to a companion partÐthe
MM57HS HiSeC Decoder. For applications requiring more
extensive receiver design and decoder programming, a
COPS8xxx/NM93Cx6 package is recommended. A complete discussion of receiver oonfigurations and considerations can be found in the National Semiconductor Application Note: How to Design and Program a HiSeC RKE Receiver using an 8-Bit Microcontroller.
TL/D/12302 – 3
FIGURE 3. Typical Transmitter Circuit Configurations
TABLE I. LED Pin Select Options
Clock
LEDSEL
RFEN/LED
CKO/LED
Function
RC
X
RFEN
LED
RF Mode with LED
XTAL
0
LED
CKO
RF Mode w/o LED
XTAL
1
RFEN
CKO
IR mode with LED
Either the LED or RFEN outputs of the NM95HS01/02 can be used to indicate device transmission. The LED output is active during a pause, whereas the RFEN output is active during frame
transmission.
The IR Drive Current is 10 mA so an amplifier stage may be needed.
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Bit Coding Formats
IR bit coding formats all follow the same general pattern. In
this mode, a logic ‘‘1’’ is always two periods long, and a ‘‘0’’
is always three periods long. This may be an important consideration when considering preamble and sync timing.
Waveform diagrams for all available RF and IR bit transmission coding formats are shown below.
The NM95HS01/02 HiSeC Generator supports eleven-bit
coding formats which may be used for IR and RF transmission. Seven-bit formats are available for RF applications,
and four are available for IR applications. One-bit format is
reserved for future use.
Bit coding formats are selected by configuring four bits in
the EEPROM array: IRSEL, PRSEL2, PRSEL1 and PRSEL0.
Table II shows the possible bit coding options available.
Each bit coding format has a distinction which may be advantageous for a particular application. RF bit coding format
0 is the simplest bit coding scheme, and data may be easily
recovered from a transmission by exclusive OR-ing the data
and clock stream. Both RF bit coding formats 0 and 2 have
a DC level that is independent of the data.
RF format 4, and the IR modes operate with a constant
transmission energy per message, and RF coding formats
1, 3, 5 and 7 are pulse-width modulated (PWM) formats
which are relatively easy to decode. RF coding format 7 has
a low duty cycle.
The IR bit coding formats are modulated versions of RF
coding format 4, and are all suitable for IR applications. The
duty cycle and number of pulses are variable among these
four to allow the user to fine tune the IR circuit power curve.
TABLE II. Transmission Bit Coding Options
IRSEL PRSEL2 PRSEL1 PRSEL0
0
0
0
0
0
0
0
0
1
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
0
0
1
1
0
0
1
1
0
0
1
1
X
0
1
0
1
0
1
0
1
0
1
0
1
X
Function
RF Bit Coding Format 0
RF Bit Coding Format 1
RF Bit Coding Format 2
RF Bit Coding Format 3
RF Bit Coding Format 4
RF Bit Coding Format 5
Reserved
RF Bit Coding Format 7
IR Bit Coding Format 1
IR Bit Coding Format 2
IR Bit Coding Format 3
IR Bit Coding Format 4
Reserved
Bit Transmission Coding Formats
RF Bit Coding Format 0 (Manchester Code)
RF Bit Coding Format 1 (33%/66% Ð End High)
TL/D/12302 – 6
TL/D/12302 – 7
RF Bit Coding Format 2 (50% Duty Cycle)
RF Bit Coding Format 3 (25%/50% Ð Start High)
TL/D/12302 – 8
TL/D/12302 – 9
RF Bit Coding Format 4 (IR Style)
RF Bit Coding Format 5 (33%/66% Ð Start High)
TL/D/12302 – 10
TL/D/12302 – 11
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Bit Transmission Coding Formats (Continued)
RF Bit Coding Format 7 (Low Duty Cycle Ð 1:16/2:16)
TL/D/12302 – 12
IR Bit Coding Format 1 (5 Pulses Ð 33% Duty Cycle)
TL/D/12302 – 13
IR Bit Coding Format 2 (8 Pulses Ð 33% Duty Cycle)
TL/D/12302 – 14
IR Bit Coding Format 3 (5 Pulses Ð 25% Duty Cycle)
TL/D/12302 – 15
IR Bit Coding Format 4 (8 Pulses Ð 25% Duty Cycle)
TL/D/12302 – 16
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The sync frame format contains both start code and a fixed
4-bit sync code of 0000. This sync code replaces the key
application data in the data field, and is used to confirm
HiSeC sync mode to the decoder.
Programmable Signal
Output Polarity
The transmit (TX) output pin signal polarity and quiescent
state output is controlled by the TxPol bit, which may be
configured in EEPR0M. If TxPol e 0, the TX output pin will
be at a logic low when no frame is transmitted, or when a
‘‘0’’ appears as data in a frame. Conversely, if TxPoI e 1,
the TX output pin will be at a logic high when no frame is
transmitted, or when a ‘‘1’’ appears as data in a frame.
This option allows the designer to choose between a configuration where a logic ‘‘1’’ represents power transmission
(for example, when an RF stage is activated by driving the
base of an NPN transistor), and a configuration where a
logic ‘‘0’’ represents power transmission (for example, when
an IR LED is connected between VCC and the TX output).
Sync mode is built into the generator to allow resynchronization of the device under certain conditions as a convenience to the end user. If the designer wishes to preclude
any possible resynchronization, the presence of the sync
code allows the decoder to detect any synchronization attempt.
Since the length of several fields is adjustable, there are
several possibilities for the length of a sync frame. The
shortest possible sync frame is 45 bits, and the longest possible sync frame is 96 bits. 40 bits of start code, 4 bits of
sync code, and 1 stop bit are always present.
The composition of a sync frame is shown in Figure 5.
Data Frames
0/11 bits
The NM95HS01/02 HiSeC Generator transmits the encrypted data it generates as data frames. These frames are
transmitted through an IR or RF transmitter stage using the
bit coding format selected.
The NM95HS01/02 transmits two types of data frames: a
normal data frame, and a synchronization (sync) frame. The
format of each frame is similar, but there are slight differences to suit the purposes of each. Normal data frames are
used to transmit encoded data in general operation. Sync
frames are used to synchronize (or initialize) the HiSeC to its
decoder.
Data frames are comprised of a number of different fields.
Each field occupies a fixed position in the data frame, and
serves a specific purpose. Most data fields are user-configurable to some extent. The user may enable/disable the
presence of a field, control its length, or modify its format.
The user also has several options available to tailor the data
frame transmission format, such as pause time between
frames, and time-out time. Options are configured by programming the on-chip EEPR0M array. The content and format of each of the fields is discussed below.
Preamble
0/8 bits
0/20/24 bits
4 bits
24/36 bits
0/8 bits
1 bit
Sync
Key ID
Data
Dynamic
Parity
Stop
Field
Field
Field
Code
Field
Bit
FIGURE 4. Normal Data Frame Configuration
0/11 bits
Preamble
0/8 bits
0/20/24 bits
4 bits
40 bits
0/8 bits
1 bit
Sync
Key ID
Sync
Start
Parity
Stop
Field
Field
Code
Code
Field
Bit
FIGURE 5. Sync Frame Configuration
Data Frame Fields
Data frames are comprised of a number of data fields. Each
field occupies a fixed position in the data frame, and serves
a specific purpose. Most data fields are user-configurable by
programming the on-chip EEPROM array. The content and
format of each field is discussed below, as well as the EEPROM options available.
All data frame fields are transmitted Most Significant Bit
first.
THE PREAMBLE
The user has the option of allowing a preamble to be transmitted as the first frame of either a normal data frame or a
sync frame. This option is enabled/disabled by setting the
PreamblePresent bit in the EEPROM array. PreamblePresent e 0 means no preamble is transmitted. PreamblePresent e 1 means an 11-bit preamble is transmitted as described below.
The purpose of the preamble is to generate a relatively long,
clearly recognizable bit pattern to give the decoder a
chance to ‘‘wake up’’ and configure its logic circuits and
registers. This allows the receiver to be placed in a standby
mode to conserve power for battery applications.
The preamble is only transmitted once as the first frame of a
data transmission, regardless of how long the key is held
down, although the remaining frames of the data transmission (including any inter-frame pauses) will continue to repeat as long as the key remains depressed.
NORMAL DATA FRAME
The NM95HS01/02 HiSeC Generator transmits normal data
frames in general operating mode. Frame transmission begins each time a key switch is asserted, and continues as
long as the key is held down. The device has an option to
terminate transmitting data frames, and go into halt mode, if
a key is held down for more than 80 seconds (if the
TlMEOUTEN feature has been enabled).
The normal data frame format contains both dynamic code
and key application data (in the data field). Since the length
of several fields is adjustable, there are several possibilities
for the length of the data frame. The shortest possible normal data frame is 29 bits, and the longest possible normal
data frame is 92 bits. 24 bits of dynamic code, 4 bits of key
application data, and 1 stop bit are always present.
The composition of a normal data frame is shown in Figure 4.
SYNC FRAME
The NM95HS01/02 HiSeC Generator transmits sync
frames only in sync mode so that it can synchronize itself
with its decoder. This mode occurs only during initialization
of the device, or after holding a key down for more than 10
seconds (if the AutoResync feature has been enabled).
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Data Frame Fields (Continued)
The sync field data is programmable, and can be encoded
with any user-selected bit coding format, or with an NRZ
(unencoded binary) bit format. The option to select between
a user bit coding format and NRZ format is set by configuring the SyncType bit in the EEPROM array. If SyncType e
0, sync field data is sent according to the user-selected IR
or RF bit coding format. If SyncType e 1, the information is
sent in NRZ format with the bit length determined by the
chosen IR or RF bit coding format.
For NRZ bit coding, both high and low bit times are the
same as the IR or RF bit coding time. For bit coding modes
where the ‘‘1’’s and ‘‘0’’s have different bit lengths Ð all IR
modes for example Ð the length of the NRZ ‘‘1’’ and ‘‘0’’
bits have correspondingly different bit lengths.
RF bit coding format 7 is a special case. As in the other
formats, if SyncType e 0, information is sent according to
the user-set IR or RF bit coding format. However, if SyncType e 1, a ‘‘0’’ is sent using the bit coding determined by
the IR or RF coding format, and a ‘‘1’’ is sent as an NRZ
zero. This is to maintain the ‘‘spirit’’ of the low duty cycle
arrangement for RF format 7.
The preamble has a fixed format of two bit times at system
logic high, then one-bit time at system logic low, then eight
zeroes using the user-selected bit coding format. This arrangement is clearly shown in Figure 6 for several bit coding
formats.
If desired, a preamble may be isolated from the frame by
eight-bit times at logic low during a frame transmission. This
can be achieved by enabling the sync field in NRZ mode
with the byte 0h.
SYNC FIELD
If enabled, the sync field is transmitted in every normal data
frame or sync frame to provide a bit timing reference for the
rest of the frame. This allows the decoder to determine the
proper bit coding format the generator is using, and to synchronize to it.
The sync field option is set with the SyncPresent bit in the
EEPROM array. If SyncPresent e 0, no sync field is sent. If
SyncPresent e 1 an 8-bit sync field is included in the data
transmission. This 8-bit field is transmitted Most Significant
Bit first.
Figure 7 shows sync field examples for several bit coding
formats.
TL/D/12302 – 17
FIGURE 6. Preamble Format Examples
TL/D/12302 – 18
FIGURE 7. Sync Field ExampIes for Data Byte 03h
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Data Frame Fields (Continued)
DYNAMIC CODE FIELD
KEY ID FIELD
The key ID field is another user option. Both its presence
and the length of its field can be configured in EEPROM. If
FixPresent e 0, no key ID field will be transmitted with the
frame. If FixPresent e 1, a 24-bit field will be transmitted.
The contents of the key ID field are programmable by the
user. Its purpose is to provide a unique identification code
for each user key to allow a decoder to identify a particular
key in applications where a decoder may be configured for
multiple keys. Since the key ID register allows 24 bits, there
are 224 possible key combinations. Each user key will be
unique, and take full advantage of the HiSeC Generator’s
high security coding scheme.
The field size is selected with the FixSize bit. If FixSize e 1,
the 24-bit field is selected. If FixSize e 0, the 20-bit field is
selected. Since a full 24 bits are allowed in the Key ID register, the NM95HS01/02 will transmit the most significant 20
bits if FixSize e 0. The field is transmitted in the user-selected bit coding format.
The dynamic code field is transmitted with every frame, and
its length is programmable. If DynSize e 0, a 24-bit field is
sent; if DynSize e 1, a 36-bit field is sent. Its function is to
provide a secure dynamic code which changes with each
new transmission. The field is the result of combining the
11-, 13-, and 16-bit CRC registers using non-linear logic and
feedback. The result of this process is stored in the
24-/36-bit buffer register. If DynSize e 0, 24 of the possible
36 bits are transmitted in the field. Increasing the field
length provides additional security.
The start code field in a sync frame is a special case of the
dynamic code field. In sync mode, 40 bits of data are sent
regardless of the setting of the DynSize bit.
PARITY FIELD
The parity field is an 8-bit field that is transmitted with every
frame to ensure data integrity. It is a user option that is
enabled by setting ParityPresent e 1.
The parity check is a bytewise exclusive OR-ing of all the
bytes in the data frame from the sync field to the dynamic
code field. The preamble, parity field and stop bit are not
included. In practice, the parity process works as follows: bit
m of the 8-bit parity field is a modulo 2 addition of the data
frame bits m, m a 8, m a 16, . . . to the end of the frame. If
the addition of the ‘‘1’’s in these bits is odd, bit m of the
parity field is set to ‘‘1’’. If the addition is even, bit m is set to
‘‘0’’. This process is continued for all 8 parity bits.
If the frame is not byte aligned, the parity field is calculated
by zero extending the last four bits, calculating the bytewise
exclusive OR-ing of all the bytes as described above, then
swapping the higher and lower nibbles to give the correct
parity.
DATA FIELD
The data field is transmitted with every frame. It has several
uses, which are discussed here.
The primary use of the data field is to indicate which key
switch has been pressed. Since each key switch input can
be associated with a particular application, the decoder can
determine which function to initiate.
The data field is 4 bits long, and each key switch input is
associated with a particular bit in the field. If any key switch
is pressed, its corresponding bit in the data field will be seen
as a ‘‘1’’. Any key switch not pressed is seen as a default
‘‘0’’. Key bits are transmitted in the order: K1, K2, K3, K4.
The sync code field in the sync frame is a special case of
the data field, and is found in the same position in the data
frame. In any sync frame, the sync code is always 0000, so
the decoder can always distinguish between a normal data
frame and a sync frame. Since each bit represents a key,
and a data frame is initiated as a result of pressing a key, it
is not possible to have all zeroes in a normal data frame.
The data field can also serve as a low battery indicator. This
is an option which can be enabled by setting the CompareEnable bit. If CompareEnable e 1, and the NM95HS01/02
detects a low battery level, the device will signal that fact by
alternating between transmitting normal data frames with
the correct key usage information, and transmitting normal
data frames with a data field of 1111. In the first data frame,
the data field will represent the true state of the four key
inputs. In the next frame, this field will be all ones. This
sequence will be repeated as long as frames are being
transmitted. For sync frames, this field will not alternate, and
the data will remain 0000 regardless of the battery level.
Setting CompareEnable e 0 disables the low battery detect
option.
STOP BIT
The stop bit is present in all frames. It is used to delimit the
end of the frame for bit formats that require a definite end. It
is necessary for formats that end with a long zero pulse. IR
modes require a stop bit to distinguish between a ‘‘0’’ and a
‘‘1’’ in the next-to-last bit of a frame. The stop bit is read as
a ‘‘1’’, and is added for all modes.
DATA FRAME SEQUENCING AND TRANSMISSION
The NM95HS01/02 becomes operational any time a key is
pressed. When this happens, the code generator logic is
clocked to randomize the data and generate a new rolling
code. Once the code is generated, data frames using this
new code are repeatedly transmitted over the TX output pin
as long as the key remains pressed. These data frames are
separated by a pause whose length is programmable.
The transmission sequence is always begun by a preamble
if this option is enabled. The preamble is only transmitted
once, since its function is to wake the decoder from sleep
mode if it is powered down for battery conservation. The
preamble is then followed by a data frame, pause, data
frame, pause, . . . etc.
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Data Frame Fields (Continued)
HiSeC GENERATOR TIMER BLOCK
TRANSMISSION INDICATION
Both the LED and RFEN signals can be used to indicate
HiSeC rolling code transmission. The LED output is active
low during the transmission of a pause, whereas the RFEN
output is active low during transmission of either a frame or
a pause. Either output may be used to provide a visual indication of transmission by connecting an LED between VCC
and LED or RFEN.
If the low battery detect option is enabled, and the battery is
low, the LED output is active only during the pause following
the first frame of a new code transmission. It is not active on
successive pauses, in order to conserve power.
Bit timing and several function operating times are set in the
generator through a user programmable timer block. This
timer block is used to provide IR and RF bit timing signals,
the interframe pause time, the AutoResync timing period,
and the time-out delay.
The NM95HS01/02 timer block consists of three programmable 6-bit prescalers and a fixed 16-bit prescaler. The input to Prescaler1 is (/4 of the frequency of CKI. The output is
the IR clock. This signal becomes the input to Prescaler2.
The output from Prescaler2 is the RF clock. This signal then
becomes the input to Prescaler3. The output from Prescaler3 is a target value of 2.5 ms. Finally. this 2.5 ms timing
signal becomes the input to the fixed 16-bit prescaler. There
are several outputs from this prescaler. The 2.5 ms is divided by 4, 4096 and 32768, and these times are used to set
the key debounce time (10 ms), the AutoResync time
(l10 sec), and the generator time-out period (l80 sec),
respectively.
The NM95HS01/02 timer block is shown in Figure 8.
Operational Timing Issues
DATA FRAME PAUSE LENGTH
After the complete transmission of a data frame, a pause is
inserted before the next data frame is transmitted. The
pause length can be modifed by configuring the 2-bit PauseLength parameter in EEPR0M. PauseLength is broken down
into two single bit parameters, Pause1 and Pause0. Available configuration options are shown in Table III.
The purpose of the prescalers is to provide various timing
signals to the state machines in the generator. The IR clock
is used as a time base for the various IR bit coding formats.
The RF clock is used for RF bit coding formats. A programmable bit called SCLK determines whether the IR clock
(SCLK e 0) or the RF clock (SCLK e 1) is used as the bit
timing time base. In addition to SCLK, the system designer
can program Prescaler1, Prescaler2 and Prescaler3 separately to set the necessary division factors. Since each of
these prescalers is 6 bits, permissible values range from 2
to 64.
The system designer must set the programmable prescalers
to meet the necessary timing requirements for all the functions discussed above. All of these timings are interdependent.
TABLE III. Pause Length Select Options
PAUSE1
PAUSE0
0
0
1
1
0
1
0
1
Function
0
8
20
50
Pause Time
c P3 Output
c P3 Output
c P3 Output
c P3 Output
No Pause
20 ms
50 ms
100 ms
HiSeC GENERATOR TIME-OUT
If the NM95HS01/02 time-out option is enabled
(TIMEOUTEN e 1), the device will enter halt mode 80 seconds after a key is first activated, regardless of whether the
key is still being pressed. This option guards against the
condition that a key may be stuck low, which could drain the
battery. If TIMEOUTEN e 0, the generator will continue to
transmit data frames as long as a key is pressed.
Figure 9 provides the basis for an example in calculating the
necessary timing for these functions, and setting the timer
block appropriately.
TL/D/12302 – 19
FIGURE 8. The NM95HS01/02 Timer Block
TL/D/12302 – 20
FIGURE 9. NM95HS01/02 Timer Block Example
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10
Operational Timing Issues (Continued)
tor assumes a 6V battery, and sets the low battery detect
region to approximately 4.4V to 4.8V. If BatteryType e 0,
the comparator assumes a 3V battery, and sets the low
battery detect region to approximately 2.2V to 2.4V.
Data output signals are sampled for low voltage at the start
of the data field during frame transmission. If a low battery
voltage level is detected, and the detect option is enabled,
the LED will signal the condition by flashing at the first
pause in the data frame transmission, and alternating normal data field data with a data field containing all ones. This
procedure is explained more fully in the Data Field section.
As an example, consider the following situation. A designer
wishes to design an RF data transmitter using RF bit coding
format 5 with a bit time of 1 ms. The designer also wishes to
use a 3 MHz crystal oscillator as the system clock.
The required bit time of 1 ms encompasses three RF clock
periods for RF bit coding format 5. Therefore, the RF clock
time needs to be (/3 of 1 ms ( e 333 ms). The timer block has
a target value of 2.5 ms (2500 ms) as the output of Prescaler3. Since the RF clock signal is divided by Prescaler3, Prescaler3 divides the signal by 2500/333 e 7.5. This figure is
rounded off to become 8.
One point of possible confusion should be clarified here.
Whenever a division value is calculated for any of the 3
prescalers, the prescaler should be configured with one unit
less than that division value. For example, in this case, we
calculated a division value of 8 (after rounding) for Prescaler3. Therefore, Prescaler3 should be programmed with 8 b
1 e 7.
Next we calculate values for Prescaler1 and Prescaler2.
Although the crystal oscillator uses both the CKI and CKO
pins, only the CKI input is relevant here. The CKI input frequency is 3 MHz, and (/4 of that is 0.75 MHz. This is the
input frequency to the HiSeC timer block, and the corresponding timing signal is 1.33 ms.
Since the RF clock must be 333 ms, Prescalers1 and 2 together must divide by 333/1.33 e 250. A convenient choice
would be to make Prescaler1 divide by 10 and Prescaler2
divide by 25.
Therefore, load Prescaler1 with 10 b 1 e 9, and Prescaler2 with 25 b 1 e 24.
Security Aspects
The basis of the HiSeC Generator is to provide a means
of communicating information between the device and its
decoder across some distance. Since data is transmitted
at a distance, there is a possibility of signal interception
and unauthorized use of the data by a third party. The
NM95HS01/02 has been designed to provide such a high
level of complexity and correlation immunity that intercepting the signal is immaterial.
INITIALIZATION/SYNCHRONIZATION
Initialization is the process of synchronizing the generator with its decoder for the first time. The NM95HS01/02
uses the following procedure to initialize the device.
The user inserts a new battery into the HiSeC-based device,
which causes the LED to light. The LED also has a secondary function for synchronization and initialization procedures. It will light to prompt the end user that it expects
some action, and therefore serves as a guide.
When the LED lights, the user presses a key. The LED will
go off as the generator begins randomizing its registers, and
configuring its internal logic. When the user releases the
key, the LED will light a second time. This is a signal for the
user to press a key again. This second action shifts the
generator into sync mode. This causes the NM95HS01/02
to transmit at least four sync frames, allowing the decoder
to synchronize to the generator. The generator then exits
sync mode, and is ready tor normal operation.
DEBOUNCE LOGIC
The key switch input signals are connected to the debounce
logic block, which continuously polls the inputs to determine
if a key switch has been asserted. If a key switch has been
asserted, its normally high input will be seen as a low. lf the
input is seen low for four continuous debounce strobe signals, it is considered to be a stable signal, and its associated output from the debounce logic block is set high. This
enables the generator control logic, and a code is generated and transmitted.
This debounced output signal is deasserted as soon as the
key is released and its signal goes high again. This assumes
normal operation. However, if a key remained pressed for a
long time, the generator might time-out before seeing the
signal go high again (if TIMEOUTEN e 1). The generator
would then enter halt mode even if the key remained
pressed. The generator would come out of halt mode when
it saw the falling edge of another key input, which would
occur when another key is pressed.
RESYNCHRONIZATION
If synchronization is lost between the generator and its decoder, resynchronization is accomplished using a sync
frame. A sync frame is generated in two cases: when the
battery is removed and replaced, or the user initiates an
initialization procedure by holding Key Switch 1 and Key
Switch 2 simultaneously for 5 seconds.
A sync frame provides the decoder with enough information
to ‘‘learn’’ the key and synchronize to it.
For the highest possible security protection, resynchronization can be completely excluded by configuring the decoder
to recognize, and refuse to act upon, the transmission of a
sync frame. The sync frame format is discussed more fully
elsewhere, but briefly, it can be recognized by the presence
of all zeroes in the data field. In this case, if synchronization
is lost between the generator and decoder, they could not
be made to function together.
LOW BATTERY DETECT OPTION
The NM95HS01/02 contains an internal comparator circuit
that detects low battery voltage, and indicates this condition
to the data frame generator. The CompareEnable parameter in EEPROM enables this function (CompareEnable e
1). During halt mode, the comparator is switched off completely to minimize power consumption. The BatteryType
parameter in EEPROM selects the threshold voltage range
for the comparator. If BatteryType e 1, the compara-
11
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Security Aspects
Generator Clock Design
Parameters
NORMAL OPERATION
Tables IV, V, and VI provide a basis for selecting component
values for both the RC clocked generator (NM95HS01) and
the crystal (XTAL) oscillator clocked generator
(NM95HS02).
The component values shown in the tables have been chosen for low cost, general availability, and reliable operation.
Components are referenced to the circuit schematics
shown in Figure 3. Though there is some flexibility in selecting alternate values, there are constraints on permissible
component values.
All resistors and capacitors should be kept within the following ranges; 3 kX s Rx s 200 kX and 50 pF s Cx s 200 pF.
Once the NM95HS01/02 has been initialized, the device will
generate and transmit a new code each time a key is
pressed. If a key is held down, the same frame (plus any
pauses between frames) is transmitted repeatedly. If the
key is held down for longer than 80 seconds, the generator
will go into halt mode to conserve battery power, and will
stop transmitting data frames (if the TIMEOUTEN option is
enabled).
Another option available during normal generator operation
is the ability to generate a resync after a key has been
pressed for more than 10 seconds (if the AutoResync option is enabled). This option allows the end user to resynchronize the generator if necessary, without having to remove and replace the battery.
TABLE IV. RC Clock Components,
TA e 25§ C, VCC e 5V – 6.5V
FORWARD CALCULATION AND CODE WINDOWS
Aside from using a sync frame, there is another way to ensure the NM95HS01/02 remains in sync with its decoder
during normal operation. The decoder can perform a forward calculation to predict what the next generator codes
will be. This is an important point, and should be considered
carefully in designing the decoding system.
In a well-designed system, the decoder should be able to
calculate forward for some reasonable number of codes,
and store the results for future reference. This allows the
decoder to remain in sync even if it misses one or more
codes from the generator. This could occur if the receiver
did not receive a transmission clearly, or if someone activated the keys outside the range of the receiver.
Increasing the depth of this code window would allow the
decoder to miss a greater number of codes from the generator, and still remain in sync. One method for implementing
a code window is to include a MICROWIRETM EEPROM
(such as the NM93Cx6) in the decoder design, and store the
codes in memory. This becomes even more important if the
decoder is designed to accomodate several HiSeC generator devices. In this case, the decoder should have a code
window available for each device.
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R (kX)
C (pF)
CKI (MHz)
CKI (ns)
3.3
82
2.12 – 2.32
470 – 430
5.6
100
1.1 – 1.17
870 – 850
6.8
100
0.9 – 0.95
1100 – 1050
TABLE V. RC Clock Components,
TA e 25§ C, VCC e 2.5V
R (kX)
C (pF)
CKI (MHz)
CKI (ns)
3.3
82
1.53 – 1.6
650 – 600
5.6
100
0.9 – 1
1100 – 1000
6.8
100
0.8 – 0.83
1250 – 1200
TABLE VI. XTAL Clock Components,
TA e 25§ C, VCC e 2.5V – 6.5V
12
R1 (MX)
C1 (pF)
C2 (pF)
CKI (MHz)
CKI (ns)
1
30
30 –36
4
250
Generator Clock Design Parameters (Continued)
TABLE VII. NM95HS01/02 EEPROM Array Configuration and Definitions
Parameter
Bits
Address
Function
AutoResync
1
Byte 0, bit 7
Allows user to send a sync frame by holding a key down for l10 seconds
LEDSEL
1
Byte 0, bit 6
Determines whether RFEN/LED or CKO/LED is the LED connect pin for the
NM95HS02
BatteryType
1
Byte 0, bit 5
Selects between 3V and 6V battery voltage
TIMEOUTEN
1
Byte 0, bit 4
Disables data transmission if key is depressed l80 seconds
Pause Length
(Pause0/Pause1)
2
Byte 0, bits 3–2
Sets the pause time between data frames during data transmission
(0/20/50/100) ms
FactoryDisableBit
1
Byte 0, bit 1
Disables ability to write to Byte 12
WriteDisableBit
1
Byte 0, bit 0
Enables/disables ability to write into EEPROM array
PreamblePresent
1
Byte 1, bit 7
Enables/disables presence of preamble field
SyncType
1
Byte 1, bit 6
Determines if sync field is sent in user-selected IR/RF format or default NRZ
format
SyncPresent
1
Byte 1, bit 5
Enables/disables presence of sync field
FixSize
1
Byte 1, bit 4
Determines length of Key ID field (0/20/24 bits)
FixPresent
1
Byte 1, bit 3
Enables/disables presence of Key ID field
DynSize
1
Byte 1, bit 2
Determines length of Dynamic Code field (24/36 bits)
ParityPresent
1
Byte 1, bit 1
Enables/disables presence of parity field
CompareEnable
1
Byte 1, bit 0
Enables/disables low battery detect option
BitTransmitFormat
IRSel
PRSeI2,1,0
1
3
Byte 2, bit 7
Byte 2, bits 6–4
Selects among the 12 possible IR/RF bit coding formats
Selects between IR and RF bit coding formats
Used with IRSeI to select particular bit coding format
TxPol
1
Byte 2, bit 3
Sets the quiescent output state and data logic level on the TX output pin
SCLK
1
Byte 2, bit 2
Determines whether the IR clock or RF clock is used as the bit timing time
base
Prescaler3
6
Byte 2, bits 1–0
Byte 3, bits 7–4
Sets interframe delay time and key debounce time (Also generates timeout
delay time)
Prescaler2
6
Byte 3, bits 3–0
Byte 4, bits 7–6
Sets RF Clock timing
6
Prescaler1
Byte 4, bits 5–0
Sets IR Clock timing
DynamicCode
24
Bytes 5–7
Sets initial configuration of the Rolling Code registers
KeyIDCode
24
Bytes 8–10
Sets user-configurable key identification register
SyncFieldCode
8
Byte 11
Sets configuration of sync field register
Reserved
8
Byte 12
Reserved for factory use Ð unique customized algorithm option
Note: The first bit clocked into the device is Byte 0, bit 7. The seventh and eight bits are the chip disable bits. Once they are set, and VCC is removed, the chip will
be disabled.
13
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Absolute Maximum Ratings (Note 1)
Ambient Storage Temperature
a 300§ C
Lead Temperature (Soldering, 10 sec.)
ESD Rating
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.
Ambient Operating Temperature
NM95HS01/NM95HS02
NM95HS01E/NM95HS02E
b 65§ C to a 150§ C
Input or Output Voltages with Respect to Ground
b 0.5V to a 7V
All except K1 or K2
b 0.5V to a 13V
K1 or K2
2000V
0§ C to a 70§ C
b 40§ C to a 85§ C
Power Supply (VCC) Range
2.2V to 6.5V
NM95HS01/02 DC and AC Electrical Characteristics
2.2V s VCC s 6.5V (unless otherwise specified)
Min
Typ
Max
Units
VCC
Symbol
Supply Voltage
Parameter
Conditions
2.5
5.0
6.5
V
VRW
Read/Write Voltage
4.5
5.0
5.5
V
VSV
Supervoltage
(Note 2)
11.5
12.0
12.5
V
ICC
Supply Current
Halt Mode (3.0V) (Note 2)
Halt Mode (6.0V)
Normal Mode
CKI e 0 MHz, VCC e 3.0V
CKI e 0 MHz, VCC e 6.0V
CKI e 4.1 MHz, VCC e 6V
0.1
0.5
1
1
2
3
mA
mA
mA
VIH
Input Voltage (High)
CKI: Logic High
All Others; Logic High
VIL
Input Voltage (Low)
CKI: Logic Low
All Others: Logic Low
IP
Pullup Current
VCC e 6V, VIN e 0V
IRF
Leakage Current (RFEN)
VCC e 6V, RFEN e 6V
IOUT
Output Current
Source (Push-Pull)
Sink (Push-Pull)
VCC e 4.5V, VOH e 3.3V
VCC e 4.5V, VOL e 0.4V
0.8 VCC
0.7 VCC
V
V
0.2 VCC
0.2 VCC
35
120
250
mA
1
mA
10
15
mA
mA
tPS
Power Supply Rise Time
IMP
Max. Sink-Source Current per Pin
VTH
Comparator Threshold Voltage
BattType e 0 (3V)
BattType e 1 (6V)
2.2
4.4
tWW
K1 Initiate Write Time
tWW e tWHW a tWLW
40
ms
tWHW
Write Time High
20
ms
tWLW
Write Time Low
20
ms
tSW
K2 Setup Time
20
ms
tHW
K2 Hold Time
20
ms
tPW
Program Write Time
10
ms
tCKIHSW
Supervoltage Low to Clock High Time
10
ms
tSVLW
Clock Low to Supervolt High Time
10
ms
tXW
Exit Write Time
tDSW
Data Setup Time
100
tDHW
Data Hold Time
100
tWR
Initiate K1 Read Time
tWHR
Read Time High
tWLR
Read Time Low
tCKIHSR
Start Read Time
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1 ms
V
V
10 ms
10
tWR e tWHR a tWLR
10
14
10 ms
20
mA
2.4
4.8
V
V
ms
ns
ns
40
ms
20
ms
20
ms
ms
NM95HS01/02 DC and AC Electrical Characteristics
2.5V s VCC s 6.5V (unless otherwise specified) (Continued)
Max
Units
tCKI
Symbol
Clock Period Time
(Note 4)
Parameter
XTAL Clock
RC Clock
Conditions
2000
2000
Min
Typ
DC
DC
ns
ns
tCKIH
Clock High Time
(Note 4)
XTAL Clock
RC Clock
1000
1000
DC
DC
ns
ns
tCKIL
Clock Low Time
(Note 4)
XTAL Clock
RC Clock
1000
1000
DC
DC
ns
ns
tDAR
Data Access Time
tDAR e tCKIH a tDALR
tDALR
Data Access Time Low
tENDR
End Read Time
10
ms
tSVLR
K1 Supervoltage Low Time (Read)
10
ms
tXR
Exit Read Time
10
ms
1.1
ms
100
ns
Note 1: Stresses above those listed under ‘‘Absolute Maximum Ratings’’ may cause permanent damage to the device. This is a stress rating only, and functional
operation of the device at these or any other conditions above those indicated in the operational sections of the specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect device reliability.
Note 2: The standby current of k 1 mA is tested at 3V. During HALT Mode only a very small current is required to maintain the code in the shift registers. HALT
mode is exited by depressing one of the input keys.
Note 3: The clock rate used to program the NM95HS01/02 is generally less than the normal operating mode clock rate, and should be temporarily reduced as
necessary to meet the programming specifications shown here. For example, a generator might normally operate at 4 MHz, but should be programmed at
s 0.5 MHz (2000 ns).
Note 4: Parameter characterized but not 100% tested.
Capacitance TA e a 25§ C, f e 1 MHz (Note 2)
Test
Max
Units
CIN
Symbol
Input Capacitance
7
pF
COUT
0utput Capacitance
12
pF
Typical Halt Mode Current (nA) vs Voltage over Temperature
TL/D/12302 – 23
15
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Timing Diagrams
Write Mode
TL/D/12302 – 21
Read Mode
TL/D/12302 – 22
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16
pulses applied to CKI to initialize the part. (See Timing Diagram on pg. 16.) After this initialization, K2 is brought to
supervoltage. K1 is then brought to supervoltage. Now K2 is
brought back to VRW, then K1 is brought back to VRW. The
NM95HS01/02 is now in Write mode.
To program the first byte, set K1 back to supervoltage, and
place the first byte of data (VIH and VIL pulses) onto K2
(starting with the Least Significant Bit). As each bit is placed
on K2, clock the CKI pin to latch the bit. When all bits of the
first byte have been latched in, set K1 to VRW, and poll the
TX output pin for a logic low. This confirms the
NM95HS01/02 has written the byte to memory. Repeat this
sequence to program the remainder of the bytes. When all
13 bytes have been programmed, set K1 and K2 to 0V to
end Write mode.
Programming the NM95HS01/02
The NM95HS01/02 HiSeC Generator uses four pins to read
and write the 13 bytes of on-chip EEPROM. These are the
Key1 (K1), Key2 (K2), TX, and CKI pins. K1 functions as the
chip select line, K2 functions as the data strobe, CKI serves
as the serial clock, and TX acts as the data out pin.
Three voltage levels are required to program the device:
Supervoltage (VSV), Read/Write voltage (VRW), and Ground
(0V). Supervoltage is used to select Read and Write modes
in the device. These modes can only be entered by applying
supervoltage to K1 and K2. This alleviates the risk of the
device entering these modes during normal operation.
The programming protocol for the NM95HS01/02 on-chip
EEPROM array was designed to match National Semiconductor’s MICROWIRE format closely. However, there are
several differences. One is the need to use a supervoltage
to select modes. Another concerns the CKI clock input.
Upon power-up, the NM95HS01/02 CKI input must be
clocked a minimum of 1500 times to ensure the part is ready
for programming. This allows the internal state machines
and registers to perform their necessary power-on sequences. (See Table VII.)
Read Mode
The NM95HS01/02 HiSeC Generator can be placed in
Read mode by applying supervoltage to K1. Upon powerup, both K1 and K2 must be set to VRW, and a minimum of
1500 clock pulses applied to CKI to initialize the part. (See
Timing Diagram on pg. 16.) After this initialization, K1 is
brought to supervoltage. Then K1 is brought back to VRW.
The NM95HS01/02 is now in Read mode.
To read the first byte, set K1 back to supervoltage, and
clock the CKI pin 8 times, while polling TX. EEPROM data is
sent Most Significant Bit first. Continue clocking CKI to read
the remainder of the bytes. When all 13 bytes have been
read, set K1 back to VRW. Set K1 and K2 to 0V to end Read
mode.
Write Mode
The NM95HS01/02 HiSeC Generator can be placed in
Write mode when supervoltage is applied to both K1 and K2
in a specific sequence. Upon power-up, both K1 and K2
must be set to VRW, and a minimum of 1500 clock
Programmer Support for NM95HS01/02
Worldwide third party support is provided by:
Vendor
Contact Number
Xeltek
SuperPro-EM
Universal
Programmer
Europe: 49-5722-203-125 (Germany)
America: 408-524-1929
Asia: 65-296-6433 (Singapore)
BBS: 408-245-7082
National Semiconductor
NM95HS-PRO-X
Americas: 800-272-9959
System General
Turpro-1 Univeral
Device Programmer
Switzerland: 31-921-7844
America: 408-263-6667/800-967-4776
Taiwan: 886-2-917-3015
BBS: 408-262-6438
Hi-Lo ALL-07
Asia: 886-2764-0215
America: 510-623-3850
Evalutation kit support for NM95HS01/02. A demonstration kit for the
HiSeC High Security Rolling Code Generator is available:
National Semiconductor
NM95HSEV
NM95HSPRO
HiSeC Evaluation Board
HiSeC Single Site Programmer
17
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Physical Dimensions inches (millimeters) unless otherwise noted
8-Lead (0.150× Wide) Molded Small Outline Package, JEDEC
Order Number NM95HS01M8 or NM95HS02M8
NS Package Number M08A
14-Lead (0.150× Wide) Molded Small Outline Package, JEDEC
Order Number NM95HS01M14 or NM95HS02M14
NS Package Number M14A
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18
Physical Dimensions inches (millimeters) unless otherwise noted (Continued)
8-Lead Dual-In-Line Package
Order Number NM95HS01N, NM95HS01EN, NM95HS02N or NM95HS02EN
NS Package Number N08E
14-Lead (0.300× Wide) Molded Dual-In-Line Package
Order Number NM95HS01N14 or NM95HS02N14
NS Package Number N14A
19
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NM95HS01/NM95HS02 HiSeC High Security Rolling Code Generator
Physical Dimensions all dimensions are in millimeters (Continued)
14-Lead Molded Thin Shrink Small Outline Package, JEDEC
Order Number NM95HS01MT14/NM95HS02MT14
NS Package Number MTC14
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DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF NATIONAL
SEMICONDUCTOR CORPORATION. As used herein:
1. Life support devices or systems are devices or
systems which, (a) are intended for surgical implant
into the body, or (b) support or sustain life, and whose
failure to perform, when properly used in accordance
with instructions for use provided in the labeling, can
be reasonably expected to result in a significant injury
to the user.
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Corporation
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Tel: 1(800) 272-9959
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2. A critical component is any component of a life
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be reasonably expected to cause the failure of the life
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effectiveness.
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