mc33899vwr2 Freescale Semiconductor, Inc, mc33899vwr2 Datasheet - Page 14

• Manufacturer Part Number: mc33899vwr2
• Description: Programmable H-bridge Power Ic
• Manufacturer: Freescale Semiconductor, Inc

LOAD CURRENT FEEDBACK (CSNS)
current back to the microcontroller via the CSNS pin. It
supplies a current that is 1/400
Equation 1). An analog multiplexer routes the enabled high-
side current to the CSNS pin. An external resistor connected
to the CSNS pin (R
circuit operates properly in the presence of high-frequency
noise. An external capacitor may be necessary to provide
filtering.
CHARGE PUMP RESERVOIR CAPACITOR (CRES)
operating VIGNP range that is sufficient to drive the output
MOSFETs and ensure that the output R
are met. An external reservoir capacitor of 0.1 µF is
recommended. The charge pump operates at approximately
2.0 MHz to 4.0 MHz in order to prevent interference with AM
entertainment radio.
AUTOMATIC OUTPUT RE-ENABLE DISABLE
(REDIS)
MOSFET once the REDIS input voltage exceeds 4.0 V. An
external capacitor (C
Equation 2). Once a low-side current comparator is tripped, a
120
either the next rising edge of PWM or the 4.0 V trip level is
achieved. This re-enables the low-side output MOSFET and
14
33899
FUNCTIONAL DESCRIPTION
FUNCTIONAL PIN DESCRIPTION
The load current sense circuit mirrors a sample of the load
Note This output is clamped so that it will not exceed V
The charge pump provides an output voltage over the full
The REDIS input pin automatically re-enables the low-side
µ
A current source linearly charges the capacitor until
LSCmp
PWM
V
CSNS
CSNS
REDIS
=
) sets current to voltage gain. The
5 - 10 µs
Pulse Out
I
400
OUT
) determines the time interval (see
5 - 10 µs
th
.
R
of the load current (see
CSNS
DS(ON)
5 - 10 µs
Blank Time
Figure 8. LS Current Comparator One Shot
specifications
Eq. 1
5 - 10 µs
Pulse Out
CC
.
> 40 µs
I
LS Current Comparator
load
HIGH-SIDE AND LOW-SIDE SLEW TIME CONTROL
(RS)
low- and high-side drive outputs) are adjustable from 5.0 µs
(50 kΩ RS) to 1.0 µs (10 kΩ RS) to reduce high-frequency
harmonic energy in the vehicle’s wiring harness. In addition,
slew time control is programmable to be either 1X, 2X, or 4X
(via the SPI) to lower power dissipation at elevated die
temperatures. The characteristics of the turn-on and turn-off
voltage are linear, with no discontinuities, during the output
driver state transitions. If the RS pin detects an impedance of
less than 5.0 kΩ to ground or greater than 1.0 MΩ to ground,
it defaults to the fastest slew time of 1.0 µs.
LOW-SIDE COMPARATOR ONE SHOT OUTPUT
(LSCMP)
time the low-side comparator is tripped. Then the output goes
low during a 5 µs to 10 µs blanking time. If another low-side
comparator trip event is detected during the blanking time,
another 5 µs to 10 µs pulse high occurs immediately after the
blanking interval.
discharges the capacitor to 0 V. This feature is disabled by
grounding this input.
a nominal 75 µs time interval.
The turn-on and the turn-off slew times on S0 and S1 (both
The LSCMP output pin pulses high for 5 µs to 10 µs any
As per the above equation, a 2.2 nF capacitor will provide
The REDIS min duration = 25 µs,
dt =
C
REDIS
so C
Analog Integrated Circuit Device Data
5 - 10 µs
I
REDIS
.
dv
=
must be > 1 nF
C
Freescale Semiconductor
120 µA
.
4.0 V
Eq. 2