NCV7520
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14
duration of the channel’s fault retry (or refresh) time (t
FR
).
Once active, the refresh timer will run to completion and the
output will follow the input at the end of the retry interval.
The timer is reset when ENB = 1 or when the mode is
changed to latch−off (provided no SCB or GLO fault is
present in the channel’s status).
Table 4. GATE & MODE SELECT REGISTER
R0
A2 A1 A0 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 P
0 0 0 M5 M4 M3 M2 M1 M0 G5 G4 G3 G2 G1 G0 ?
1 = AUTO RETRY
DEFAULT = LATCH OFF
1 = GATx ON
DEFAULT = ALL OFF
Diagnostic Pulse Select − Register R1
The NCV7520 has functionality to perform either
on−state or off−state diagnostic pulses (Table 5) The
function is provided for applications having loads normally
in a continuous on or off state. The diagnostic pulse function
is available for both latch−off and auto−retry modes. The
pulse executes for the selected channel(s) on low−high
transition on CSB. Default after reset is R1.D[11:0] = 0. R1
is an echo type response register.
Diagnostic pulses have priority and are not dependant on
the input (IN
X
, G
X
) or the output (GAT
X
) states. The pulse
does not execute if: ENB = 1 (device is disabled); both an
ON and OFF pulse is simultaneously requested for the same
channel; an ON or OFF pulse is requested and a SCB
(shorted load) diagnostic code is present for the selected
channels; an ON or OFF pulse is requested while a pulse is
currently executing in the selected channels (i.e. a blanking
timer is active); the selected channels are currently under
auto−retry control (i.e. refresh timer is active).
When R1.F
X
= 1, the diagnostic OFF pulse command is
executed. The open load diagnostic is turned on if disabled
(see Diagnostic Config 2 − R3), the output changes state for
the programmed t
BL(OFF)
blanking period, and the
diagnostic status is latched if of higher priority than the
previous status. The output assumes the currently
commanded state at the end of the pulse.
When R1.N
X
= 1, the diagnostic ON pulse command is
executed. The output changes state for the programmed
t
BL(ON)
blanking period, and the diagnostic status is latched
if of higher priority than the previous status. The output
assumes the currently commanded state at the end of the
pulse. A flowchart for the diagnostic pulse is given in
Figure 16.
Table 5. DIAGNOSTIC PULSE SELECT REGISTER
R1
A2 A1 A0 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 P
0 0 1 F5 F4 F3 F2 F1 F0 N5 N4 N3 N2 N1
N0
?
1 = DIAGNOSTIC OFF PULSE
DEFAULT = 0
1 = DIAGNOSTIC ON PULSE
DEFAULT = 0
Diagnostic Config 1 − Register R2
The diagnostic Config 1 register programs the turn−on/off
blanking time and shorted load fault detection references for
each channel (Table 6) Bits R2.C[2:0] select which channels
receive the configuration data (Table 7). Bit R2.C[4] selects
the turn−on blanking time range (PV = passenger vehicle,
CV = commercial vehicle) and bits R2.C[8:5] select
turn−on/off blanking time (Table 8). Bits R2.C[11:9] select
the fault reference (Table 9). Default after reset is indicated
by “(DEF)” in the tables. R2 is an echo type response
register.
If a blanking timer is currently running when the register
is changed, the new value is accepted but will not take effect
until the next activation of the timer.
Table 6. DIAGNOSTIC CONFIG 1 REGISTER
R2
A2 A1 A0 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 P
0 1 0 C11 C10 C9 C8 C7 C6 C5 C4 C3 C2 C1 C0 ?
%VFLTREF
SELECT
TBLANK
OFF
TBLANK
ON
TIMER
RANGE
CHANNEL
SELECT
