5829 Datasheet, PDF (7/12 Pages) Allegro MicroSystems – 9-BIT SERIAL-INPUT, LATCHED SINK DRIVER

5829
9-BIT SERIAL-INPUT,
LATCHED SINK DRIVER
APPLICATIONS INFORMATION
The UCN5829EB is designed to drive high-current, 9- or 24-wire
(3 devices cascaded) dot matrix impact printer solenoids. The internal
CMOS control logic:
1) selects the operating channels from a 9- or 24-bit word
previously loaded into the shift register,
2) controls the peak load current of the output drivers via nine
constant-frequency switch-mode current choppers,
3) sets a user-defined print enable time, and
4) turns ON an external high-side driver during the print enable
interval.
Data present at the SERIAL DATA INPUT is transferred to the shift
register on the low-to-high transition of the CLOCK input pulse. The
data must appear at the input prior to the rising edge of the clock input
waveform. On succeeding clock pulses, the registers shift data infor-
mation towards the SERIAL DATA OUTPUT. Information present at
any register is transferred to its respective latch on the high-to-low
transition of the STROBE (serial-to-parallel conversion). Drivers that
have a logic high stored in their latch will be enabled for a set time
interval (t_EN) generated by an internal one-shot. The output current is
internally sensed and controlled in a fixed-frequency chopper format.
Between strobe pulses, a new data word can be clocked in for the next
print enable cycle.
PRINT ENABLE TIME
A high-to-low transition of the STROBE input starts an internal
one-shot which sets the print enable time (t_EN) of the output drivers and
the external high-side driver. The print enable time is determined by an
external resistor (50 kΩ max) and capacitor (100 pF min) at RC_EN as
t_EN = R_EN C_EN
The print enable time can also be controlled from a microproces-
sor. In this mode, the internal one-shot is operated as an output
disable function. In this mode, R_EN and C_EN are not used; instead a
10 kΩ series resistor is connected between RC_EN and an externally
generated output disable pulse. As before, on the high-to-low
STROBE transition, the outputs will be enabled. They will remain
enabled until a low-to-high logic (≥3.3 V) DISABLE transition at RC_EN.
When operating in a continuous chopping mode, and neither print
enable timeout nor output disable are desired, RC_EN should be
grounded.