A8286 Datasheet PDF - Allegro MicroSystems

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A8286
Allegro MicroSystems

Part Number A8286
Description Dual LNB Supply and Control Voltage Regulator
Page 19 Pages


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A8286
Dual LNB Supply and Control Voltage Regulator
Features and Benefits
2-wire serial I2C™ -compatible interface: control (write)
and status (read)
LNB voltages (16 programmable levels) compatible with
all common standards
Tracking switch-mode power converter for lowest dissipation
Integrated converter switches and current sensing
Provides up to 650 mA per channel and 1.0 A total
continuous load current
Provides up to 700 mA per channel and 1.1 A total for 2000 ms
Output current limit of 900 mA typical, with 48 ms timer
Static current limit circuit allows full current at startup and
1318V output transition; reliably starts wide load range
Push-pull output stage minimizes 1318V and 1813V
output transition times for highly capacitive loads
Adjustable rise/fall time via external timing capacitor
Built-in tone oscillator, factory-trimmed to 22 kHz
facilitates DiSEqC™ tone encoding, even at no-load
Four methods of 22 kHz tone generation, via I2C™ data
bits and/or external pin
22 kHz tone detector facilitates DiSEqC™ 2.0 decoding
Auxiliary modulation input
LNB overcurrent with timer
Provides VOUT within 19 to 21 VDC at 700 mA for
SWM (single wire multiswitch) operation
Diagnostics for output voltage level, input supply UVLO,
and DiSEqC™ tone output
Cable disconnect diagnostic
Package:
28 pin 5 mm × 5mm
QFN/MLP (suffix ET)
Description
Intended for analog and digital satellite receivers, this dual
low-noise block converter regulator (LNBR) is a monolithic
linear and switching voltage regulator, specifically designed to
provide the power and the interface signals to two LNB down
converters via coaxial cables. TheA8286 requires few external
components, with the boost switches and compensation circuitry
integrated inside of the device. A high switching frequency is
chosen to minimize the size of the passive filtering components,
further assisting in cost reduction. The high level of component
integration ensures extremely low noise and ripple figures.
The A8286 has been designed for high efficiency, utilizing
the Allegro® advanced BCD process. The integrated boost
switches have been optimized to minimize both switching and
static losses. To further enhance efficiency, the voltage drop
across the tracking regulators has been minimized.
The A8286 has integrated tone detection capability, to support
full two-way DiSEqC™ communications. Several schemes
are available for generating tone signals, all the way down
to no-load, and using either the internal clock or an external
time source.
Continued on the next page…
VS
VDD
A Channel 1 of 2 channels shown.
B R8-C11 network is needed only when high
inductive load is applied, such as ProBrand LNB.
C D3 and D4 are used for surge protection.
D Either C12 or C9 should be used, but not both.
Functional Block Diagram
C2
100 MF
A
Channel 1 L1
33 MH
L3
D1 1 MH
A8286
C5
100 MF
C6
1 MF
R4 R5
C4
100 nF
TDO1 EXTM1
LX1 GNDLX1
BOOST1 VCP1
VIN
C1
100 nF
VREG
C3
220 nF
Regulator
R3
R2
R1
SDA
SCL
I2 C
Compatible
Interface
IRQ
Boost
Converter
Charge
Pump
C12 D
TMode1
EXTM1
Fsw
DAC
LNB
Voltage
Control
Wave
Shape
TCAP1
TGate1
Fault Monitor
OCP1
OCP2
PNG1
PNG2
TSD
VUV
Fsw
Clock
Divider 22 kHz
Oscillator
PAD
GND
VPump
Linear
Stage
TDO1
Tone
Detect
R6
157
LNB1
C8
D2 220 nF
L2
220 MH
R8
30 7
C9
220 nF
D
TCAP1
C7
10 nF
C11
0.68 MF
B
TDI1
R7
100 7
C10
10 nF
D3
C
VOUT1
C13
10 nF
D4
C
8286-DS, Rev. 3



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A8286
Dual LNB Supply and Control Voltage Regulator
Description (continued)
A comprehensive set of fault registers are provided which, comply
with all the common standards, including: overcurrent, thermal
shutdown, undervoltage, cable disconnect, power not good, and
tone detect.
The device uses a 2-wire bidirectional serial interface, compatible
with the I2C™ standard, that operates up to 400 kHz.
The A8286 is supplied in a lead (Pb) free 28-lead
MLP/QFN with 100% matte tin leadframe.
Absolute Maximum Ratings
Characteristic
Symbol
Conditions
Rating
Units
Load Supply Voltage, VIN pin
Output Current*
VIN
IOUT
16
Internally
Limited
V
A
Output Voltage; BFI, BFO, LNB, LX, and BOOST pins
–1 to 33
V
Output Voltage; VCP pin
Logic Input Voltage, EXTM pin
VCP
–1 to 41
–0.3 to 5
V
V
Logic Input Voltage, other pins
–0.3 to 7
V
Logic Output Voltage
–0.3 to 7
V
Operating Ambient Temperature
TA
–20 to 85
°C
Junction Temperature
TJ(max)
150 °C
Storage Temperature
Tstg
–55 to 150
°C
*Output current rating may be limited by duty cycle, ambient temperature, and heat sinking. Under any set of conditions, do not exceed the specified
current ratings, or a junction temperature, TJ, of 150°C.
Package Thermal Characteristics*
Package
RθJA
(°C/W)
PCB
ET 32
4-layer
* Additional information is available on the Allegro website.
Ordering Information
Use the following complete part numbers when ordering:
Part Number
Packinga
A8286SETTR-Tb
7-in. reel, 1500 pieces/reel
12 mm carrier tape
aContact Allegro for additional packing options.
bLeadframe plating 100% matte tin.
Description
ET package, MLP surface mount
Allegro MicroSystems, Inc.
2
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com



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A8286
Dual LNB Supply and Control Voltage Regulator
Device Pin-out Diagram
BOOST1 1
VCP1 2
TCAP1 3
NC 4
TDO1 5
EXTM1 6
TDI1 7
PAD
21 BOOST2
20 VCP2
19 TCAP2
18 NC
17 TDO2
16 EXTM2
15 TDI2
Terminal List Table
Name
Number
GND
ADD
BOOST1
BOOST2
EXTM1
11
1
21
6
EXTM2
16
GND
8
PAD
GNDLX1
GNDLX2
IRQ
LNB1
LNB2
Pad
27
23
14
28
22
LX1 26
LX2 24
NC
SCL
SDA
TCAP1
TCAP2
TDI1
4, 13, 18
12
10
3
19
7
TDI2
15
TDO1
5
TDO2
VCP1
VCP2
VIN
VREG
17
2
20
25
9
(Top View)
Function
Fused internally; connect to ground plane for thermal dissipation
Address select
Tracking supply voltage to linear regulator (channel 1)
Tracking supply voltage to linear regulator (channel 2)
External modulation input (channel 1)
External modulation input (channel 2)
Signal ground
Exposed thermal pad; connect to ground plane
Boost switch ground (channel 1)
Boost switch ground (channel 2)
Interrupt request
Output voltage to LNB (channel 1)
Output voltage to LNB (channel 2)
Inductor drive point (channel 1)
Inductor drive point (channel 2)
No connection
I2C™-compatible clock input
I2C™-compatible data input/output
Capacitor for setting the rise and fall time of the LNB output (channel 1)
Capacitor for setting the rise and fall time of the LNB output (channel 2)
Tone detect input (channel 1)
Tone detect input (channel 2)
Tone detect output (channel 1)
Tone detect output (channel 2)
Gate supply voltage (channel 1)
Gate supply voltage (channel 2)
Supply input voltage
Analog supply
Allegro MicroSystems, Inc.
3
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com



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A8286
Dual LNB Supply and Control Voltage Regulator
ELECTRICAL CHARACTERISTICS at TA = 25°C, VIN = 8 to 16 V, unless noted otherwise1
Characteristics
Symbol
Test Conditions
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 Time2
Output Voltage Pull-Down Time2
Output Reverse Current
Err
Relative to selected VLNB target level,
ILOAD = 0 to 500 mA
IIN(Off)
ENB bit = 0, LNB output disabled, VIN = 12 V
IIN(On)
ENB bit = 1, LNB output enabled, ILOAD = 0
mA, VIN = 12 V
RDS(on)BOOST ILOAD = 500 mA
fSW
ILIMSW
VREG
VBOOST – VLNB, no tone signal,
ILOAD = 500 mA
ICHG
TCAP capacitor (C7) charging
IDISCHG TCAP capacitor (C7) discharging
tr(VLNB)
For VLNB 13 18 V; CTCAP = 5.6 nF,
ILOAD = 500 mA
tf(VLNB)
For VLNB 18 13 V; CLOAD = 100 μF,
ILOAD = 0 mA
IRLNB
ENB bit = 0, VLNB = 33 V , BOOST capacitor
(C5) fully charged
Ripple and Noise on LNB Output, Peak-to-Peak2
Protection Circuitry
Vrip,n(pp) 20 MHz bandwidth
Output Overcurrent Limit
Overcurrent Disable Time
VIN Undervoltage Lockout Threshold
VIN Turn On Threshold
Undervoltage Hysteresis
Thermal Shutdown Threshold2
Thermal Shutdown Hysteresis2
Power Not Good Flag Set
Power Not Good Flag Reset
Power Not Good Hysteresis
Cable Disconnect Boost Voltage
ILIMLNB
tDIS
VUVLO
VIN(th)
VUVLOHYS
TJ
TJ
PNGSET
PNGRESET
PNGHYS
VCAD
VIN falling
VIN rising
With respect to VLNB
With respect to VLNB
With respect to VLNB
CADT bit = 1, ENB bit = 1, VSEL0 through
VSEL3 = 1
Cable Disconnect Set
Cable Disconnect Current Source
VCADSET
ICADSRC
VLNB = 21.00 V, VBOOST = 22.8 V
Min.
–4.5
320
3.0
600
–12.5
7.5
800
40.0
7.05
7.40
77
82
22.0
20.16
1.0
Typ. Max. Units
– 4.5 %
– 12.0 mA
– 20.0 mA
300 600 mΩ
352 384 kHz
3.8 4.8
A
800 1000 mV
–10 –7.5
10 12.5
μA
μA
500 –
μs
12.5 –
ms
1 5 mA
30 – mVPP
900 1000
48 56.0
7.35 7.65
7.70 8.00
350 –
165 –
20 –
85 93
90 98
5–
22.8 23.5
21.00 21.84
1.75 2.5
mA
ms
V
V
mV
°C
°C
%
%
%
V
V
mA
Continued on the next page…
Allegro MicroSystems, Inc.
4
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com



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