a8291 Allegro MicroSystems, Inc., a8291 Datasheet - Page 4

• Manufacturer Part Number: a8291
• Description: A8291 Single Lnb Supply And Control Voltage Regulator
• Manufacturer: Allegro MicroSystems, Inc.

A8291
ELECTRICAL CHARACTERISTICS
Continued on the next page…
General
Set-Point Accuracy, Load and Line Regulation
Supply Current
Boost Switch On Resistance
Switching Frequency
Switch Current Limit
Linear Regulator Voltage Drop
TCAP Pin Current
Output Voltage Rise Time
Output Voltage Pull-Down Time
Output Reverse Current
Ripple and Noise on LNB Output
Protection Circuitry
Output Overcurrent Limit
Overcurrent Disable Time
VIN Undervoltage Lockout Threshold
VIN Turn On Threshold
Undervoltage Hysteresis
Thermal Shutdown Threshold
Thermal Shutdown Hysteresis
Power Not Good Flag Set
Power Not Good Flag Reset
Power Not Good Hysteresis
Cable Disconnect Boost Voltage
Cable Disconnect Set
Characteristics
4
2
2
2
2
3
Single LNB Supply and Control Voltage Regulator
at T
A
= 25°C, V
R
PNG
DS(on)BOOST
V
PNG
V
PNG
Symbol
V
I
∆V
t
t
I
UVLOHYS
I
DISCHG
V
I
I
r(VLNB)
LIMLNB
V
f(VLNB)
I
CADSET
LIMSW
rip,n(pp)
V
IN(Off)
IN(On)
I
RLNB
t
∆T
f
CHG
UVLO
Err
IN(th)
SW
DIS
T
CAD
REG
RESET
J
SET
HYS
J
IN
= 8 to 16 V, unless noted otherwise
Relative to selected V
I
ENB bit = 0, LNB output disabled, V
ENB bit = 1, LNB output enabled,
I
I
V
V
I
TCAP capacitor (C7) charging
TCAP capacitor (C7) discharging
For V
I
For V
I
ENB bit = 0, V
(C5) fully charged
20 MHz BWL; reference circuit shown in
Functional Block diagram; contact Allegro for
additional information on application circuit
board design
V
V
V
With respect to V
With respect to V
With respect to V
CADT bit = 1, ENB bit = 1, VSEL0 through
VSEL3 = 1
LOAD
LOAD
LOAD
LOAD
LOAD
LOAD
IN
BOOST
BOOST
IN
IN
= 10 V, V
falling
rising
LNB
LNB
= 0 to 450 mA
= 0 mA, V
= 450 mA
= 450 mA
= 450 mA
= 0 mA
– V
– V
13 → 18 V; C
18 → 13 V; C
LNB
LNB
OUT
, no tone signal,
LNB
Test Conditions
= 800 mV
IN
= 20.3 V
LNB
LNB
LNB
= 12 V
= 33 V , BOOST capacitor
LNB
TCAP
LOAD
target level,
= 5.6 nF,
= 100 μF,
1
IN
= 12 V
115 Northeast Cutoff, Box 15036
Allegro MicroSystems, Inc.
Worcester, Massachusetts 01615-0036 [phone]
www.allegromicro.com
–12.5
20.16
–4.5
7.05
7.40
22.0
Min.
320
600
500
7.5
40
77
82
–
–
–
–
–
–
–
–
–
–
–
–
21.00
Typ.
12.5
7.35
7.70
22.8
300
352
800
–10
500
600
350
165
3.0
10
30
48
20
85
90
–
–
–
1
5
21.84
Max.
1000
10.0
19.0
–7.5
12.5
7.65
8.00
23.5
600
384
700
4.5
56
93
98
–
–
–
5
–
–
–
–
–
mV
Units
kHz
mΩ
mA
mA
mV
mA
mA
mV
ms
ms
μA
μA
μs
°C
°C
%
%
%
%
A
V
V
V
V
PP
4