MagTek LOW POWER SHIFT-OUT - Manual (Page 10)

Low Power Shift-Out IntelliHead
4
CURRENT CONSUMPTION †
Note: Refer to the timing diagrams in 99875337 for complete information.
Iarm =
120 μA maximum
Iswipe =
1.2 mA maximum (internal oscillator running)
Iextract = 20
μA maximum
Cstrb =
[1 nF maximum + parasitic capacitance of PCB] (this is the total capacitance driven by
STROBE and its effects; sometimes called power-dissipation-capacitance)
Fstrb =
User-controlled frequency of STROBE during data extraction
IdataLow = 48 μA maximum
Irst_int =
1.2 mA maximum (internal oscillator running; subtract IdataLow if DATA is released
before Irst_int expires)
Ioff =
1.5 μA typical at 25 °C; 13 μA maximum at 85 °C (STROBE drive leakage into MCU
not included)
Example calculation for current consumption during New Mode data extraction:
Maximum parasitic PCB capacitance on STROBE (example) = 20 pF
Cstrb = 1 nF + 20pF
Fstrb = 1MHz
VDD = 3.3 V
Imax = Iextract + Fstrb * Cstrb * VDD
Imax = (20 μA) + (1 MHz) * (1020 pF) * (3.6 V)
Imax = 3.7 mA
Notes:
1) The duration of Iarm is very brief when using the low power armed-to-read feature. It
exists only from the time STROBE falls at the beginning of a card, until the time that the
ASIC is able to recognize the card. This duration is one bit-cell maximum (swipe speed
dependent).
2) When treating this unit as a regular Shift-Out IntelliHead, an additional current of up to
190uA will exist in the armed-to-read state (Iarm) due to a 20 kΩ nominal pull-up in the
Low Power Shift-Out IntelliHead. Except in the armed-to-read state, this 20 kΩ nominal
resistor may be a pull-up or pull-down depending upon actual head signals.
† Red font indicates a difference relative to 99875337.