Electrical characteristics – MagTek TTL User Manual
Page 28
I/O Interface for TTL Magnetic Stripe Readers
24
Absolute Maximum Ratings (Non-Operating)
Supply Voltage .........................7.0 Volts
Voltage Input Range.................0 to VCC
Output Sink Current..................10 mA
Internal Power Dissipation........100 mW
Storage Temperature Range....-55 to 150
°C
Lead Soldering (10 Sec.)..........260
°C
Electrical Characteristics
Unit operates from 2.7 to 5.5 Volts (VCC) and -30
° to 70°C
Test conditions: VCC = 5.00 Volts, Ambient Temperature = 25
°C
Table 1: Electrical Characteristics.
Parameter Condition
Min.
Max.
Typ.
Units
Device Current
2
mA
Logic Low Out (VOL)
at +2.0 mA
1
0.4
Volts
Logic High Out (VOH) at -2.0 mA
1
VCC - 0.5
Volts
Oscillator Frequency
(
2
)
1.2
MHz
Notes:
1. TTL/CMOS compatible. Outputs covered include the following: Card Present, Read Data, Strobe and F/2F.
2. Frequency measured using R2 and C3 component values. Refer to recommended circuit for required values.
Signal Timing Diagram
Notes:
1. Card Present, Data, and Strobe are negative true logic.
2. Card Present goes low after 14-15 head flux reversals.
3. Card Present returns to high level approximently 150mS after the last flux transition.
4. Data is valid 1.0µS (min.) before the leading negative edge of strobe and remains valid until approximently 1.0µS
before the next STROBE.
DATA
The DATA signal is valid while the STROBE is low. If the DATA signal is high, the bit is a zero. If the DATA signal is
low, the bit is a one.
STROBE
The STROBE signal indicates when DATA is valid. It is recommended that DATA be loaded by the user with the
leading negative edge of the STROBE.
CARD PRESENT
CARD PRESENT will go low after 14-15 flux reversals from the head. It will return high if Reset or about 150
milliseconds after the last flux reversal. The CARD PRESENT signal can be tied together with other card present
signals from more than one IC, however use only one pull-up resistor (R4). E.g., if this is a 3 track reader, all 3 CARD
PRESENTS would be tied together using a single 10K resistor.