a8286 Allegro MicroSystems, Inc., a8286 Datasheet - Page 8

• Manufacturer Part Number: a8286
• Description: Dual Lnb Supply And Control Voltage Regulator
• Manufacturer: Allegro MicroSystems, Inc.

A8286
ODT (Overcurrent Disable Time)
If the LNB output current exceeds 900 mA typical, for more than
48 ms, then the LNB output will be disabled and the OCP bit will
be set.
Short Circuit Handling
If the LNB output is shorted to ground, the LNB output current
will be clamped to 900 mA, typical. If the short circuit condition
lasts for more than 48 ms, the A8286 will be disabled and the
OCP bit will be set.
Auto-Restart
After a short circuit condition occurs, the host controller should
periodically re-enable the A8286 to check if the short circuit has
been removed. Consecutive startup attempts should allow at least
5 s of delay between restarts.
In-rush Current
At start-up or during an LNB reconfiguration event, a tran-
sient surge current above the normal DC operating level can be
provided by the A8286. This current increase can be as high as
900 mA, typical, for as long as required, up to a maximum of
48 ms.
I
per channel
Figure 1. ODT (Overcurrent Disable Timing) Mode Timing Diagram
OUT(LNBX)
,
+A
0
≤t
ODT (Overcurrent Disable Timing) Mode Timing Diagram
DIS
Dual LNB Supply and Control Voltage Regulator
900 mA, typ.
per channel
Start-up
2000 ms
700 mA for one channel,
and 1.1 A total current
Continuous Operation
650 mA for one channel,
and 950 mA total current
DC current
The A8286 can handle up to 700 mA per channel individually,
or 950 mA to both channels simultaneously, during continuous
operation.
Tone Detection
A 22 kHz tone detector is provided in each channel of the A8286
solution. The detector extracts the tone signal and provides it as
an open-drain signal on the TDO pins. The maximum tone out
error is ±1 tone cycle, and the maximum tone out delay with
respect to the input is 1 tone cycle. Detection thresholds are given
in table 1.
Table 1. Detection Thresholds for Tone Generation Options
Guaranteed
Safe Operating Area
Threshold
Threshold
Detection
Rejection
TMODE
TGATE
(Fig. 1)
(mV
(mV
Option
Reconfiguration
EXTM
PP
PP
≤t
LNB
DIS
)
)
Control
Continuous Operation
400
100
0/1
1
1
1
Control
400
100
0/1
2
1
1
Transmit
115 Northeast Cutoff, Box 15036
Allegro MicroSystems, Inc.
Worcester, Massachusetts 01615-0036 [phone]
www.allegromicro.com
continuous
Circuit
Short
Control
≤t
22 kHz
signal,
logic
DIS
300
100
0/1
3
0
t
Control
22 kHz
gated
signal
logic
300
100
4
0
1
n.a.
300
100
must be 0 to
prevent tone
transmission
At least one
0
Receive
n.a.
400
100
1
8