A8290 Datasheet

A8290
Single LNB Supply and Control Voltage Regulator
Features and Benefits
Description
▪ 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
▪ Output current limit of 900 mA typical, with 48 ms timer
▪ Static current limit circuit allows full current at startup and
13→18 V output transition; reliably starts wide load range
▪ Push-pull output stage minimizes 13→18 V and 18→13 V
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
▪ Filter bypass MOSFET minimizes losses during tone transmit
▪ 22 kHz tone detector facilitates DiSEqC™ 2.0 decoding
▪ Diagnostics for output voltage level, input supply UVLO,
and DiSEqC™ tone output
▪ Auxiliary modulation input
▪ LNB overcurrent with timer
▪ Cable disconnect diagnostic
Intended for analog and digital satellite receivers, this single
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 an LNB down
converter via coaxial cable. The A8290 requires few external
components, with the boost switch 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 levels of component
integration ensure extremely low noise and ripple figures.
The A8290 has been designed for high efficiency, utilizing
the Allegro™ advanced BCD process. The integrated boost
switch has been optimized to minimize both switching and
static losses. To further enhance efficiency, the voltage drop
across the tracking regulator has been minimized.
The A8290 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. A DiSEqC™ filter bypass switch is also integrated, to
minimize the output impedance during tone generation.
Package: 28-pin QFN (suffix ET)
Continued on the next page…
5 mm × 5 mm
(Not to scale)
L1
33 μH
Functional Block Diagram
C2
100 μF
A R9-C11 network is needed only when a highly
inductive load is applied, such as ProBand LNB.
C1
100 nF
B
D2, D4, D5, and R10 are used for surge protection.
C
Either C12 or C9 should be used, but not both.
L3
1 MH
D1
VS
C5
100 μF
VIN
LX
C4
100 nF
C6
1 μF
GNDLX
BOOST VCP
VREG
Charge BFC
Pump
C3
220 nF
VDD
Regulator
VPump
Boost
Converter
EXTM
fsw
LNB
Voltage
Control
VOUT
Linear
Stage
SCL
fsw
L2
220 μH
LNB
TCAP
SDA
C8
D3 220 nF
TGate
OCP
PNG
TSD
VUV
C13
10 nF
R9
30 7
Fault Monitor
I 2 C™Compatible
Interface
C
BFI
Wave
Shape
BFC
TDO
C12
C11
0.68 μF
Clock
Divider 22 kHz
TCAP
C7
22 nF
Oscillator
A
ADD
TDO
IRQ
PAD
8290-DS, Rev. 16
D5
B
R7
15 7
BFO
TMode
DAC
B
B
R1 R2 R3 R4 R5 R6
EXTM
D2
R10
1 7
GND
Tone
Detect
TDI
R8
100 7
C10
10 nF
C9
220 nF
C
D4
B
A8290
Single 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 A8290 is supplied in a lead (Pb) free 28-lead MLP/QFN.
Selection Guide
Part Number
Packinga
Description
A8290SETTR-Tb
7 in. reel, 1500 pieces/reel
12 mm carrier tape
ET package, MLP surface mount
0.90 mm nominal height
aContact Allegro
bLeadframe
for additional packing options.
plating 100% matte tin.
Absolute Maximum Ratings
Rating
Units
Load Supply Voltage, VIN pin
Characteristic
Symbol
VIN
Conditions
30
V
Output Current1
IOUT
Internally
Limited
A
–0.3 to 33
V
–1 to 33
V
Output Voltage, LX pin
–0.3 to 30
V
Output Voltage, VCP pin
–0.3 to 41
V
Logic Input Voltage, EXTM and BFC pins
–0.3 to 5
V
Logic Input Voltage, other pins
–0.3 to 7
V
Logic Output Voltage
–0.3 to 7
V
Output Voltage, BOOST pin
Surge2
Output Voltage, LNB, BFI, BFO pins
Operating Ambient Temperature
TA
–20 to 85
°C
Junction Temperature
TJ(max)
150
°C
Storage Temperature
Tstg
–55 to 150
°C
1Output
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.
2Use Allegro recommended Application circuit.
Package Thermal Characteristics*
Package
RθJA
(°C/W)
PCB
ET
32
4-layer
* Additional information is available on the Allegro website.
Allegro MicroSystems, LLC
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
2
A8290
Single LNB Supply and Control Voltage Regulator
22 BFO
23 NC
24 BFI
25 VIN
26 LX
27 GNDLX
28 LNB
Device Pin-out Diagram
BOOST
1
21 NC
VCP
2
20 NC
TCAP
3
NC
4
TDO
5
17 NC
EXTM
6
16 NC
TDI
7
15 NC
19 BFC
IRQ 14
NC 13
18 NC
SCL 12
ADD 11
9
SDA 10
8
GND
VREG
PAD
(Top View)
Terminal List Table
Name
Number
ADD
11
Address select
Function
BFC
19
Bypass FET control
BFI
24
Bypass FET input (connect to LNB)
BFO
22
Bypass FET output
BOOST
1
Tracking supply voltage to linear regulator
EXTM
6
External modulation input
GND
8
Signal ground
GNDLX
27
Boost switch ground
IRQ
14
Interrupt request
LNB
28
Output voltage to LNB
LX
PAD
26
4, 13, 15-18,
20, 21, 23
Pad
SCL
12
I2C™-compatible clock input
NC
Inductor drive point
No connection
Exposed pad; connect to the ground plane, for thermal dissipation
SDA
10
I2C™ -compatible data input/output
TCAP
3
Capacitor for setting the rise and fall time of the LNB output
TDI
7
Tone detect input
TDO
5
Tone detect output
VCP
2
Gate supply voltage
VIN
25
Supply input voltage
VREG
9
Analog supply
Allegro MicroSystems, LLC
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
3
A8290
Single LNB Supply and Control Voltage Regulator
ELECTRICAL CHARACTERISTICS at TA = 25°C, VIN = 8 to 16 V, unless noted otherwise1
Characteristics
Symbol
Test Conditions
Min.
Typ.
Max.
Units
Relative to selected VLNB target level,
ILOAD = 0 to 500 mA
–3
–
3
%
IIN(Off)
ENB bit = 0, LNB output disabled, VIN = 12 V
–
–
10.0
mA
IIN(On)
ENB bit = 1, LNB output enabled,
ILOAD = 0 mA, VIN = 12 V
–
–
19.0
mA
General
Set-Point Accuracy, Load and Line Regulation
Supply Current
Boost Switch On Resistance
Err
RDS(on)BOOST ILOAD = 500 mA
Switching Frequency
fSW
Switch Current Limit
ILIMSW
VIN = 10 V, VOUT = 20.3 V
∆VREG
VBOOST – VLNB, no tone signal,
ILOAD = 500 mA
ICHG
TCAP capacitor (C7) charging
Linear Regulator Voltage Drop
TCAP Pin Current
–
300
600
mΩ
320
352
384
kHz
–
3.8
–
A
600
800
1000
mV
–12.5
–10
–7.5
μA
IDISCHG
TCAP capacitor (C7) discharging
7.5
10
12.5
μA
Output Voltage Rise Time2
tr(VLNB)
For VLNB 13 → 18 V; CTCAP = 5.6 nF,
ILOAD = 500 mA
–
500
–
μs
Output Voltage Pull-Down Time2
tf(VLNB)
For VLNB 18 → 13 V; CLOAD = 100 μF,
ILOAD = 0 mA
–
12.5
–
ms
IRLNB
ENB bit = 0, VLNB = 33 V , BOOST capacitor
(C5) fully charged
–
1
5
mA
Vrip,n(pp)
20 MHz BWL; reference circuit shown in
Functional Block diagram; contact Allegro for
additional information on application circuit
board design
–
30
–
mVPP
Output Overcurrent Limit4
ILIMLNB
VBOOST – VLNB = 800 mV
800
900
1000
mA
Overcurrent Disable Time
tDIS
40
48
56
ms
V
Output Reverse Current
Ripple and Noise on LNB Output3
Protection Circuitry
VIN Undervoltage Lockout Threshold
VUVLO
VIN falling
7.05
7.35
7.65
VIN Turn On Threshold
VIN(th)
VIN rising
7.40
7.70
8.00
V
VUVLOHYS
–
350
–
mV
Thermal Shutdown Threshold2
TJ
–
165
–
°C
Thermal Shutdown Hysteresis2
∆TJ
–
20
–
°C
With respect to VLNB
77
85
93
%
PNGRESET With respect to VLNB
82
90
98
%
–
5
–
%
22.0
22.8
23.5
V
20.16
21.00
21.84
V
1.0
1.75
2.5
mA
Undervoltage Hysteresis
Power Not Good Flag Set
Power Not Good Flag Reset
Power Not Good Hysteresis
Cable Disconnect Boost Voltage
PNGSET
PNGHYS
VCAD
Cable Disconnect Set
VCADSET
Cable Disconnect Current Source
ICADSRC
With respect to VLNB
CADT bit = 1, ENB bit = 1, VSEL0 through
VSEL3 = 1
VLNB = 21.00 V, VBOOST = 22.8 V
Continued on the next page…
Allegro MicroSystems, LLC
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
4
A8290
Single LNB Supply and Control Voltage Regulator
ELECTRICAL CHARACTERISTICS (continued) at TA = 25°C, VIN = 8 to 16 V, unless noted otherwise1
Characteristics
Symbol
Test Conditions
Min.
Typ.
Max.
Units
VBFC(H)
2.0
VBFC(L)
–
–
–
V
–
0.8
V
Bypass FET
Bypass FET Control (BFC) Logic Input
Input Leakage
Bypass FET On Resistance
Turn On/Off Delay2
IBFCLKG
RDS(on)
tD(ON/OFF)
–1
–
1
μA
ILOAD = 500 mA, and VBFC = Low, or
BFC2 bit = 1
–
0.5
1
Ω
VBFC = Low, or BFC2 bit = 1
–
650
–
μs
Tone
Tone Frequency
fTONE
20
22
24
kHz
Tone Amplitude, Peak-to-Peak
VTONE(pp)
ILOAD = 0 to 500 mA, CLOAD = 750 nF
400
620
800
mV
Tone Duty Cycle
DCTONE
ILOAD = 0 to 500 mA, CLOAD = 750 nF
40
50
60
%
Tone Rise Time
trTONE
ILOAD = 0 to 500 mA, CLOAD = 750 nF
5
10
15
μs
tfTONE
ILOAD = 0 to 500 mA, CLOAD = 750 nF
5
10
15
μs
2.0
–
–
V
Tone Fall Time
EXTM Logic Input
EXTM Input Leakage
VEXTM(H)
VEXTM(L)
–
–
0.8
V
IEXTMLKG
–1
–
1
μA
fTONE = 22 kHz sine wave, TMODE = 0
300
–
–
mV
VTDT(pp)Int
fTONE = 22 kHz sine wave, using internal tone
(options 1 and 2, in figure 2)
400
–
–
mV
VTDT(pp)Ext
fTONE = 22 kHz sine wave, using external
tone (options 3 and 4, in figure 2)
300
–
–
mV
–
–
100
mV
17.6
–
26.4
kHz
–
8.6
–
kΩ
Tone Detector
Tone Detect Input Amplitude Receive, Peak-to-Peak
Tone Detect Input Amplitude Transmit, Peakto-Peak
Tone Reject Input Amplitude, Peak-to-Peak
VTDR(pp)
VTRI(pp)
Frequency Capture
fTDI
Input Impedance2
ZTDI
fTONE = 22 kHz sine wave
600 mVpp sine wave
TDO Output Voltage
VTDO(L)
Tone present, ILOAD = 3 mA
–
–
0.4
V
TDO Output Leakage
ITDOLKG
Tone absent, VTDO = 7 V
–
–
10
μA
I2C™-Compatible Interface
Logic Input (SDA, SCL) Low Level
VSCL(L)
–
–
0.8
V
Logic Input (SDA, SCL) High Level
VSCL(H)
2.0
–
–
V
Logic Input Hysteresis
VI2CIHYS
Logic Input Current
II2CI
Logic Output Voltage SDA and IRQ
Vt2COut(L)
Logic Output Leakage SDA and IRQ
Vt2CLKG
SCL Clock Frequency
Output Fall Time
VI2CI = 0 to 7 V
ILOAD = 3 mA
Vt2COut = 0 to 7 V
fCLK
Vt2COut(H) to Vt2COut(L)
150
–
mV
<±1.0
10
μA
–
–
0.4
V
–
–
10
μA
–
–
400
kHz
–
–
250
ns
tBUF
1.3
–
–
μs
Hold Time Start Condition
tHD:STA
0.6
–
–
μs
Setup Time for Start Condition
tSU:STA
0.6
–
–
μs
Bus Free Time Between Stop/Start
tfI2COut
–
–10
Continued on the next page…
Allegro MicroSystems, LLC
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
5
A8290
Single LNB Supply and Control Voltage Regulator
ELECTRICAL CHARACTERISTICS (continued) at TA = 25°C, VIN = 8 to 16 V, unless noted otherwise1
Characteristics
Symbol
Test Conditions
Min.
Typ.
Max.
Units
I2C™-Compatible Interface (continued)
SCL Low Time
tLOW
1.3
–
–
μs
SCL High Time
tHIGH
0.6
–
–
μs
Data Setup Time
tSU:DAT
100
–
–
ns
Data Hold Time
tHD:DAT
0
–
900
ns
Setup Time for Stop Condition
tSU:STO
0.6
–
–
μs
ADD Voltage for Address 0001,000
Address1
0
–
0.7
V
ADD Voltage for Address 0001,001
Address2
1.3
–
1.7
V
ADD Voltage for Address 0001,010
Address3
2.3
–
2.7
V
ADD Voltage for Address 0001,011
Address4
3.3
–
5.0
V
I2C™
For tHD:DAT(min) , the master device must
provide a hold time of at least 300 ns for the
SDA signal in order to bridge the undefined
region of the SCL signal falling edge
Address Setting
1Operation
at 16 V may be limited by power loss in the linear regulator.
2Guaranteed by worst case process simulations and system characterization. Not production tested.
3LNB output ripple and noise are dependent on component selection and PCB layout. Refer to the Application Schematic and PCB layout
recommendations. Not production tested.
4Current from the LNB output may be limited by the choice of Boost components.
I2C™ Interface Timing Diagram
tSU:STA
tHD:STA
tSU:DAT
tHD:DAT
tSU:STO
tBUF
SDA
SCL
tLOW
tHIGH
Allegro MicroSystems, LLC
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
6
A8290
Single LNB Supply and Control Voltage Regulator
Functional Description
Protection
tracking regulator output to drive the linear regulator control.
The A8290 has a wide range of protection features and fault diagnostics which are detailed in the Status Register section.
Slew Rate Control. During either start-up, or when the output
Boost Converter/Linear Regulator
The A8290 solution contains a tracking current-mode boost
converter and linear regulator. The boost converter tracks the
requested LNB voltage to within 800 mV, to minimize power
dissipation. Under conditions where the input voltage, VBOOST ,
is greater than the output voltage, VLNB, the linear regulator must
drop the differential voltage. When operating in these conditions,
care must be taken to ensure that the safe operating temperature
range of the A8290 is not exceeded.
The boost converter operates at 352 kHz typical: 16 times
the internal 22 kHz tone frequency. All the loop compensation,
current sensing, and slope compensation functions are provided
internally.
The A8290 has internal pulse-by-pulse current limiting on
the boost converter and dc current limiting on the LNB output
to protect the IC against short circuits. When the LNB output is
shorted, the LNB output current is limited to 900 mA typical,
and the IC will be shut down if the overcurrent condition lasts
for more than 48 ms. If this occurs, the A8290 must be reenabled
for normal operation. The system should provide sufficient time
between successive restarts to limit internal power dissipation; a
minimum of 5 s is recommended.
At extremely light loads, the boost converter operates in a
pulse-skipping mode. Pulse skipping occurs when the BOOST
voltage rises to approximately 450 mV above the BOOST target
output voltage. Pulse skipping stops when the BOOST voltage
drops 200 mV below the pulse skipping level.
In the case that two or more set top box LNB outputs are connected together by the customer (e.g., with a splitter), it is possible that one output could be programmed at a higher voltage
than the other. This would cause a voltage on one output that is
higher than its programmed voltage (e.g., 19 V on the output of a
13 V programmed voltage). The output with the highest voltage
will effectively turn off the other outputs. As soon as this voltage
is reduced below the value of the other outputs, the A8290 output
will auto-recover to their programmed levels.
Charge Pump. Generates a supply voltage above the internal
voltage at the LNB pin is transitioning, the output voltage rise
and fall times can be set by the value of the capacitor connected
from the TCAP pin to GND (CTCAP or C7 in the Applications
Schematic). Note that during start-up, the BOOST pin is precharged to the input voltage minus a voltage drop. As a result,
the slew rate control for the BOOST pin occurs from this voltage.
The value of CTCAP can be calculated using the following formula:
CTCAP = (ITCAP × 6) / SR ,
where SR is the required slew rate of the LNB output voltage, in
V/s, and ITCAP is the TCAP pin current specified in the datasheet. The recommended value for CTCAP, 10 nF, should provide
satisfactory operation for most applications. However, in some
cases, it may be necessary to increase the value of CTCAP to avoid
activating the current limit of the LNB output.
One such situation is when two set-top boxes are connected in
parallel. If this is the case, the following formula can be used to
calculate a larger value for CTCAP:
CTCAP ≥ (ITCAP × 6)(2 × CBOOST) / ILIMLNB ,
CTCAP ≥ (10 μA × 6)(2 × 100 μF) / 800 mA = 15 nF .
The minimum value of CTCAP is 2.2nF. There is no theoretical
maximum value of CTCAP , however, too large a value will probably cause the voltage transition specifications to be exceeded.
Tone generation is unaffected by the value of CTCAP.
Pull-Down Rate Control. In applications that have to operate at
very light loads and that require large load capacitances (in the
order of tens to hundreds of microfarads), the output linear stage
provides approximately 40 mA of pull-down capability. This
ensures that the output volts are ramped from 18 V to 13 V in a
reasonable amount of time.
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. See figure 1, a timing diagram for this function.
Allegro MicroSystems, LLC
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
7
A8290
Single LNB Supply and Control Voltage Regulator
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 A8290 will be disabled and the
OCP bit will be set.
Auto-Restart
After a short circuit condition occurs, the host controller should
periodically reenable the A8290 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 transient surge current above the normal DC operating level can be
provided by the A8290. This current increase can be as high as
900 mA, typical, for as long as required, up to a maximum of
48 ms.
Tone Detection
A 22 kHz tone detector is provided in the A8290 solution. The
detector extracts the tone signal and provides it as an open-drain
signal on the TDO pin. 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.
Tone Generation
The A8290 solution offers four options for tone generation,
providing maximum flexibility to cover every application. The
Table 1. Detection Thresholds for Tone Generation Options
Transmit
Option
(Fig. 1)
TMODE
TGATE
1
2
3
4
n.a.
n.a.
1
Control
0/1
1
0
Control
0/1
0
0
1
DC current
900 mA,
typical
IOUT(LNBX)
1
22 kHz
Control
logic
0/1
signal,
continuous
1
Control
gated
22 kHz
logic
signal
At least one must
be 0 to prevent
tone transmission
EXTM
1
Guaranteed
Detection
Threshold
(mVPP)
400
400
300
300
300
400
Rejection
Threshold
(mVPP)
100
100
100
100
100
100
The A8290 can handle up to 700 mA per channel individually,
during continuous operation.
+A
Receive
700 mA
650 mA
Safe Operating Area
0
t
≤ tDIS
2000 ms
Start-up
≤ tDIS
≤ tDIS
Continuous Operation
Continuous Operation
LNB
Reconfiguration
Short
Circuit
Figure 1. ODT (Overcurrent Disable Timing) Mode Timing Diagram
Allegro MicroSystems, LLC
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
8
A8290
Single LNB Supply and Control Voltage Regulator
EXTM pin (external modulation), in conjunction with the I2C™
control bits: TMODE (tone modulation) and TGATE (tone gate),
provide the necessary control. The TMODE bit controls whether
the tone source is either internal or external (via the EXTM pin).
Both the EXTM pin and TGATE bit determine the 22 kHz control, whether gated or clocked.
Four options for tone generation are shown in figure 2. Note
that when using option 4, when EXTM stops clocking, the LNB
volts park at the LNB voltage, either plus or minus half the tone
signal amplitude, depending on the state of EXTM. For example,
if the EXTM is held low, the LNB dc voltage is the LNB programmed voltage minus 325 mV (typical).
With any of the four options, when a tone signal is generated,
TDET is set in the status register. When the internal tone is used
(options 1 or 2), the minimum tone detect amplitude is 400 mV,
and when an external tone is used (options 3 or 4), the minimum
tone detection amplitude is 300 mV.
DiSEqC™ Bypass MOSFET
TMODE
A pair of N-channel MOSFETs are connected in parallel (source
to drain and drain to source) to provide a low source output
impedance during tone transmission.
The MOSFETs are enabled either via the BFC input pin (active low) or by setting the BFC2 bit to 1 in the Control register.
When the BFC pin is used instead of I2C™ control, it is not
latched; a logic high or low turns the FET off or on. When the
I2C™-compatible interface is used, the BFC pin is not connected,
but the pull up resistor R5 must be present.
TGATE
I2C™-Compatible Interface
EXTM
Tone
(LNB Ref)
LNB (V)
Option 1 – Use internal tone, gated by the TGATE bit.
EXTM
TMODE
TGATE
Tone
(LNB Ref)
LNB (V)
Option 2 – Use internal tone, gated by the EXTM pin.
EXTM
TMODE
TGATE
Tone
(LNB Ref)
LNB (V)
Option 3 – Use external tone, gated by the TGATE bit.
EXTM
TMODE
TGATE
Tone
(LNB Ref)
Option 4 – Use external tone.
Figure 2. Options for tone generation
LNB (V)
This is a serial interface that uses two bus lines, SCL and SDA,
to access the internal Control and Status registers of the A8290.
Data is exchanged between a microcontroller (master) and the
A8290 (slave). The clock input to SCL is generated by the master,
while SDA functions as either an input or an open drain output,
depending on the direction of the data.
Timing Considerations
The control sequence of the communication through the I2C™compatible interface is composed of several steps in sequence:
1. Start Condition. Defined by a negative edge on the SDA line,
while SCL is high.
2. Address Cycle. 7 bits of address, plus 1 bit to indicate read (1)
or write (0), and an acknowledge bit. The first five bits of the
address are fixed as: 00010. The four optional addresses, defined by the remaining two bits, are selected by the ADD input.
The address is transmitted MSB first.
3. Data Cycles.
Write – 6 bits of data and 2 bits for addressing four internal
control registers, followed by an acknowledge bit. See Control
Register section for more information.
Read – Two status registers, where register 1 is read first,
followed by register 2, then register 1, and so on. At the start
of any read sequence, register 1 is always read first. Data is
transmitted MSB first.
4. Stop Condition. Defined by a positive edge on the SDA line,
while SCL is high. Except to indicate a Start or Stop condition, SDA must be stable while the clock is high. SDA can
only be changed while SCL is low. It is possible for the Start or
Stop condition to occur at any time during a data transfer. The
A8290 always responds by resetting the data transfer sequence.
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A8290
Single LNB Supply and Control Voltage Regulator
During a data read, the A8290 acknowledges the address in the
same way as in the data write sequence, and then retains control
of the SDA line and send the data from register 1 to the master.
On completion of the eight data bits, the A8290 releases the SDA
line before the ninth clock cycle, in order to allow the master to
acknowledge the data. If the master holds the SDA line low during this Acknowledge bit, the A8290 responds by sending the
data from register 2 to the master. Data bytes continue to be sent
to the master until the master releases the SDA line during the
Acknowledge bit. When this is detected, the A8290 stops sending
data and waits for a stop signal.
The Read/Write bit is used to determine the data transfer direction. If the Read/Write bit is high, the master reads the contents of
register 1, followed by register 2 if a further read is performed. If
the Read/Write bit is low, the master writes data to one of the two
Control registers. Note that multiple writes are not permitted. All
write operations must be preceded with the address.
The Acknowledge bit has two functions. It is used by the master to determine if the slave device is responding to its address
and data, and it is used by the slave when the master is reading
data back from the slave. When the A8290 decodes the 7-bit address field as a valid address, it responds by pulling SDA low
during the ninth clock cycle.
During a data write from the master, the A8290 also pulls SDA
low during the clock cycle that follows the data byte, in order to
indicate that the data has been successfully received. In both cases, the master device must release the SDA line before the ninth
clock cycle, in order to allow this handshaking to occur.
Interrupt Request
The A8290 also provides an interrupt request pin, IRQ, which
is an open-drain, active-low output. This output may be connected to a common IRQ line with a suitable external pull-up and can
be used with other I2C™-compatible devices to request attention
from the master controller.
acknowledge
from LNBR
Start
Address
acknowledge
from LNBR
W
Control Data
SDA
0
0
0
1
0
A1
A0
0
AK
SCL
1
2
3
4
5
6
7
8
9
I1
I0
D5
D4
D3
Stop
D2
D1
D0
AK
Write to Register
acknowledge
from LNBR
Start
Address
no acknowledge
from master
R
Status Register 1
SDA
0
0
0
1
0
A1
A0
1
AK
SCL
1
2
3
4
5
6
7
8
9
D7
D6
D5
D4
D3
D2
Stop
D1
D0 NAK
Read One Byte from Register
acknowledge
from LNBR
Start
Address
R
acknowledge
from LNBR
Status Data in Register 1
SDA
0
0
0
1
0
A1
A0
1
AK
SCL
1
2
3
4
5
6
7
8
9
D7
D6
D5
D4
D3
D2
D1
no acknowledge
from master
Status Data in Register 2
D0
AK
-
-
-
-
D3
D2
D1
Stop
D0 NAK
Read Multiple Bytes from Register
Figure 3. I2C™ Interface. Read and write sequences.
10
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A8290
Single LNB Supply and Control Voltage Regulator
the status register to determine which device is requesting attention. The A8290 latches all conditions in the Status register until
the completion of the data read. The action at the resampling
point is further defined in the Status Register section. The bits in
the Status register are defined such that the all-zero condition indicates that the A8290 is fully active with no fault conditions.
When VIN is initially applied, the I2C™-compatible interface
does not respond to any requests until the internal logic supply
VREG has reached its operating level. Once VREG has reached this
point, the IRQ output goes active, and the VUV bit is set. After
the A8290 acknowledges the address, the IRQ flag is reset. After
the master reads the status registers, the registers are updated with
the VUV reset.
The IRQ output becomes active when either the A8290 first
recognizes a fault condition, or at power-on, when the main supply, VIN , and the internal logic supply, VREG , reach the correct
operating conditions. It is only reset to inactive when the I2C™
master addresses the A8290 with the Read/Write bit set (causing a read). Fault conditions are indicated by the TSD, VUV, and
OCP bits and are latched in the Status register. See the Status register section for full description.
The DIS, PNG, CAD and TDET status bits do not cause an interrupt. All these bits are continually updated, apart from the DIS
bit, which changes when the LNB is either disabled, intentionally
or due to a fault, or is enabled.
When the master recognizes an interrupt, it addresses all
slaves connected to the interrupt line in sequence, and then reads
Start
Address
R
Status Register 1
SDA
0
0
0
1
0
A1
A0
1
AK
SCL
1
2
3
4
5
6
7
8
9
D7
D6
D5
D4
D3
D2
Stop
D1
D0 NAK
IRQ
Fault
Event
Read after Interrupt
Reload
Status Register
Figure 4. I2C™ Interface. Read sequences after interrupt request.
11
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A8290
Single LNB Supply and Control Voltage Regulator
Control Registers (I2C™-Compatible Write Register)
All main functions of the A8290 are controlled through the I2C™compatible interface via the 8-bit Control registers. As the A8290
contains numerous control options, it is necessary to have two
control registers. Each register contains up to 6 bits of data (bit
0 to bit 5), followed by 2 bits for the register address (bit 6 and
bit 7). The power-up states for the control functions are all 0s.
The following tables define the control bits for each address
and the settings for output voltage:
Table 2. Control Register Address (I1, I0) = 00
Bit 0
Bit 1
Bit 2
VSEL0
VSEL1
VSEL2
Bit 3
VSEL3
Bit 4
Bit 5
ODT
ENB
Bit 6
Bit 7
I0
I1
Bit
Name
Function
0
VSEL0
1
VSEL1
2
VSEL2
3
VSEL3
4
ODT
5
ENB
6
I0
Address Bit: 0
7
I1
Address Bit: 0
See table 4, Output Voltage Amplitude Selection
0: LNB = Low range
1: LNB = High range
1 (recommended): The ODT functions are always
enabled, but setting 1 recommended at all times.
0: Disable LNB Output
1: Enable LNB Output
These three bits provide incremental control over the voltage on the LNB output.
The available voltages provide the necessary levels for all the common standards
plus the ability to add line compensation in increments of 333 mV. The voltage
levels are defined in table 4, Output Voltage Amplitude Selection.
Switches between the low level and high level output voltages on the LNB output.
0 selects the low level voltage and 1 selects the high level. The low-level center voltage
is 12.709 V nominal and the high level is 18.042 V nominal. These may be increased
in steps of 333 mV using the VSEL2, VSEL1 and VSEL0 control register bits.
The overcurrent disable timer is always enabled
Enables the LNB output. When set to 1 the LNB output is switched on. When set to
0, the LNB output is disabled.
Address
Address
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A8290
Single LNB Supply and Control Voltage Regulator
Table 3. Control Register Address (I1, I0) = 10
Bit
0
1
Bit 0
Bit 1
Bit 2
Bit 3
Bit 4
Bit 5
Bit 6
Bit 7
Name
TMODE
TGATE
Function
0: External Tone
1: Internal Tone
0: Tone Gated Off
1: Tone Gated On
0: Cable Disconnect Test Off
2
CADT
3
-
Not Used
4
-
Not Used
5
BFC2
6
I0
Address Bit: 0
7
I1
Address Bit: 1
1: Cable Disconnect Test On
0: Bypass MOSFET Off
1: Bypass MOSFET On
TMODE Tone Mode. Selects between the use of an external 22 kHz logic signal or the use of
the internal 22 kHz oscillator to control the tone generation on the LNB output. A 0
selects the external tone and a 1 selects the internal tone. See the Tone Generation
section for more information
TGATE Tone Gate. Allows either the internal or external 22 kHz tone signals to be gated,
unless the EXTM is selected for gating. When set to 0, the selected tone (via
TMODE) is off. When set to 1, the selected tone is on. See Tone Generation Section
for more information.
CADT Cable Disconnect Test. To perform this test, set bits CADT, ENB, and VSEL0
through VSEL3 through the I2C™-compatible interface. During this test, the LNB
linear regulator is disabled, a 1 mA current source between the BOOST output and
the LNB output is enabled, and the BOOST voltage is increased to 22.8 V. After
these conditions are set, if the LNB voltage is above 21 V, it is assumed that the
coaxial cable connection between the LNBR output and the LNB head has been disconnected. In this case, the CAD bit is set in the status register. If there is a load on
the LNB pin, then the LNB voltage will decrease proportionally to the load current.
If the LNB volts drop below 19.95 V, it is assumed that the coax cable is connected
and the CAD bit in the status register is set to 0.
–
Not Used.
–
Not Used.
BFC2
Bypass MOSFET Control. When set to 1, the internal bypass MOSFETs are enabled. A 0 disables the bypass MOSFETs.
I0
Address.
I1
Address.
13
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A8290
Single LNB Supply and Control Voltage Regulator
Table 4. Output Voltage Amplitude Selection
VSEL3
VSEL2
VSEL1
VSEL0
LNB (V)
0
0
0
0
12.709
0
0
0
1
13.042
0
0
1
0
13.375
0
0
1
1
13.709
0
1
0
0
14.042
0
1
0
1
14.375
0
1
1
0
14.709
0
1
1
1
15.042
1
0
0
0
18.042
1
0
0
1
18.375
1
0
1
0
18.709
1
0
1
1
19.042
1
1
0
0
19.375
1
1
0
1
19.709
1
1
1
0
20.042
1
1
1
1
20.375
14
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A8290
Single LNB Supply and Control Voltage Regulator
Status Registers (I2C™-Compatible Read Register)
it is necessary to have two Status registers. When performing a
The main fault conditions: overcurrent (OCP), under voltage
(VUV) and overtemperature (TSD), are all indicated by setting
the relevant bits in the Status registers. In all fault cases, once the
bit is set, it remains latched until the A8290 is read by the I2C™
master, assuming the fault has been resolved.
The current status of the LNB output is indicated by the disable bit, DIS. The DIS bit is set when either a fault occurs or if
the LNB is disabled intentionally. This bit is latched, and is reset
when the LNB is commanded on again. The power not good
(PNG), tone detect (TDET), and cable disconnected (CAD) flags
are the only bits which may be reset without an I2C™ read sequence. Table 5 summarizes the condition of each bit when set and
how it is reset.
As the A8290 has a comprehensive set of status reporting bits,
multiple read function, register 1 is read followed by register 2,
then register 1 again and so on. Whenever a new read function is
performed, register 1 is always read first.
The normal sequence of the master in a fault condition will be
to detect the fault by reading the Status registers, then rereading
the Status registers until the status bit is reset indicating the fault
condition is reset. The fault may be detected either by continuously
polling, by responding to an interrupt request (IRQ), or by detecting a fault condition externally and performing a diagnostic poll of
all slave devices. Note that the fully-operational condition of the
Status registers is all 0s, to simplify checking of the Status bit.
Table 5. Status Register Bit Setting
Status Bit
Function
Set
Non-latched
Reset
Condition
Cable disconnect test off or
cable connected
CAD
Cable disconnected
DIS
LNB disabled, either intentionally or
due to fault
Latched
LNB enabled and no fault
OCP
Overcurrent
Latched
I2C™ read and fault removed
PNG
Power not good
Non-latched
LNB volts in range
TDET
Tone detect
Non-latched
Tone removed
TSD
Thermal shutdown
Latched
I2C™ read and fault removed
VUV
Undervoltage
Latched
I2C™ read and fault removed
15
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A8290
Single LNB Supply and Control Voltage Regulator
Table 6. Status Register 1
Bit 0
DIS
Bit 1
Bit 2
–
OCP
Bit 3
Bit 4
–
PNG
Bit 5
Bit 6
–
TSD
Bit 7
VUV
Bit
Name
Function
0
DIS
LNB output disabled
1
–
Not Used
2
OCP
Overcurrent
3
–
Not Used
4
PNG
Power Not Good
5
–
Not Used
6
TSD
Thermal Shutdown
7
VUV
VIN Undervoltage
LNB Output Disabled. DIS is used to indicate the current condition of the LNB
output. At power-on, or if a fault condition occurs, DIS will be set. This bit changing
to 1 does not cause the IRQ to activate because the LNB output may be disabled intentionally by the I2C™ master. This bit will be reset at the end of a write sequence
if the LNB output is enabled.
Not used.
Overcurrent. If the LNB output detects an overcurrent condition, for greater than
48 ms, the LNB output will be disabled. The OCP bit will be set to indicate that an
overcurrent has occurred and the disable bit, DIS, will be set. The Status register is
updated on the rising edge of the 9th clock pulse in the data read sequence, where the
OCP bit is reset in all cases, allowing the master to reenable the LNB output.
Not used.
Power Not Good. Set to 1 when the LNB voltage is below 85% of the programmed
voltage. The PNG bit is reset when the LNB voltage is within 90% of the programmed LNB voltage. PNG is always active so, if the LNB output is disabled, then
PNG will be a logic 1. At power-up, PNG reports a logic 1 until the LNB output is
enabled and within 90% of the programmed LNB voltage.
Not used.
Thermal shutdown. 1 indicates that the A8290 has detected an overtemperature
condition and has disabled the LNB output. The disable bit, DIS, will also be set.
The status of the overtemperature condition is sampled on the rising edge of the 9th
clock pulse in the data read sequence. If the condition is no longer present, then the
TSD bit will be reset, allowing the master to reenable the LNB output if required. If
the condition is still present, then the TSD bit will remain at 1.
Undervoltage Lockout. 1 indicates that the A8290 has detected that the input supply, VIN is, or has been, below the minimum level and an undervoltage lockout has
occurred disabling the LNB outputs. The disable bit, DIS, will also be set and the
A8290 will not reenable the output until so instructed by writing the relevant bit into
the control registers. The status of the undervoltage condition is sampled on the rising
edge of the 9th clock pulse in the data read sequence. If the condition is no longer
present, then the VUV bit will be reset allowing the master to reenable the LNB output if required. If the condition is still present, then the VUV bit will remain at 1.
16
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A8290
Single LNB Supply and Control Voltage Regulator
Table 7. Status Register 2
Bit 0
CAD
Bit 1
Bit 2
–
TDET
Bits 3 to 7
Bit
Name
Function
0
CAD
Cable Disconnected
1
–
Not Used
2
TDET
Tone Detect
3
–
Not Used
4
–
Not Used
5
–
Not Used
6
–
Not Used
7
–
Not Used
Cable between LNB and the LNB head is disconnected. When cable disconnect test
mode is applied, the LNB linear regulator is disabled and a 1 mA current source is
applied between the BOOST and LNB output. If the LNB volts rise above 21 V,
CAD will be set to 1. The CAD bit is reset if the LNB volts drop below 19.95 V.
Not used.
Tone Detect. When tone is enabled by whatever option, or if a tone signal is received from the LNB, TDET will be set to 1 if the tone appears at the LNB output.
When the tone is disabled and no tone is received from the LNB, TDET is reset.
Not used.
17
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A8290
Single LNB Supply and Control Voltage Regulator
Table 8. Component Selection Table
Component
C3
Characteristics
C8, C9b, C12b
220 nF, 50 V, X5R or X7R, 0805
C1, C4
100 nF, 50 V, X5R or X7R, 0603
C2, C5
100 μF, 35 VMIN , ESR < 75 mΩ, IRIPPLE > 700 mA
C7
C10, C13
ChemiCon: EKZE500ELL101MHB5D
Nichicon: UHC1V101MPT
Panasonic: EEU-FM1H101B
22 nF, 10 VMIN, X5R or X7R, 0402 or 0603
10 nF, 50 V, X5R or X7R, 0402 or 0603
0.68 μF, 25 VMIN, X5R or X7R, 0805
TDK: C2012X5R1E684K
Murata: GRM21BR71E684KA88
Kemet: C0805C684K3PAC
AVX: 08053D684KAT2A
C6
1.0 μF, 25 VMIN, X5R or X7R, 1206
TDK: C3216X7R1E105K
Murata: GRM31MR71E105KA01
Taiyo Yuden: TMK316BJ105KL-T
Kemet: C1206C105K3RACTU
D2, D3, D5
Schottky diode, 40 V, 1 A, SOD-123
Diodes, Inc: B140HW-7
Central Semi: CMMSH1-40
TVS, 20 VRM, 32 VCL at 500 A (8/20 μs), 3000 W
Littelfuse: SMDJ20A
ST: LNBTVS6-221S
D1
Schottky diode, 40 V, 3 A, SMA
Sanken: SFPB-74
Vishay: B340A-E3/5AT
Diodes, Inc: B340A-13-F
Central Semi: CMSH3-40MA
L1
33 H, ISAT > 2.6 A, DCR < 90 mΩ
TDK: TSL1112RA-330K2R3-PF
Taiyo Yuden: LHLC10TB330K
Coilcraft: DR0810-333L
L2
220 H, ISAT > 0.5 A, DCR < 0.8 Ω
TDK: TSL0808-221KR54-PF
Taiyo Yuden: LHLC08TB221K
Coilcraft: DR0608-224L
1 H, 1 A, DCR < 120 mΩ, 1206
Kemet: LB3218-T1R0MK
Murata: LQM31PN1R0M00L
Taiyo Yuden: LB3218T1R0M
TDK: MLP3216S1R0L
C11
D4
L3
R1 to R6
*Either
Manufacturer Device
220 nF, 10 VMIN, X5R or X7R, 0402 or 0603
Determined by VDD, bus capacitance, etc.
R7
15 Ω, 1%, 1/8 W
R8
100 Ω, 1%, 1/8 W
R9
30 Ω, 1/8 W
R10
1 Ω, 1/8 W
C9 or C12 are used, but not both.
18
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A8290
Single LNB Supply and Control Voltage Regulator
Package ET 28 Pin MLP/QFN
0.30
5.00 ±0.15
1.15
28
1
2
0.50
28
1
A
5.00 ±0.15
3.15
4.80
3.15
29X
D
SEATING
PLANE
0.08 C
C
4.80
C
+0.05
0.25 –0.07
PCB Layout Reference View
0.90 ±0.10
0.50
For Reference Only
(reference JEDEC MO-220VHHD-1)
Dimensions in millimeters
Exact case and lead configuration at supplier discretion within limits shown
+0.20
0.55 –0.10
A Terminal #1 mark area
B
3.15
2
1
28
3.15
B Exposed thermal pad (reference only, terminal #1
identifier appearance at supplier discretion)
C Reference land pattern layout (reference IPC7351
QFN50P500X500X100-29V1M);
All pads a minimum of 0.20 mm from all adjacent pads; adjust as
necessary to meet application process requirements and PCB layout
tolerances; when mounting on a multilayer PCB, thermal vias at the
exposed thermal pad land can improve thermal dissipation (reference
EIA/JEDEC Standard JESD51-5)
D Coplanarity includes exposed thermal pad and terminals
19
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A8290
Single LNB Supply and Control Voltage Regulator
Revision History
Revision
Revision Date
Rev. 16
February 15, 2012
Description of Revision
Update Absolute Maximum Ratings
I2C™ is a trademark of Philips Semiconductors.
DiSEqC™ is a trademark of Eutelsat S.A.
Allegro MicroSystems, LLC reserves the right to make, from time to time, such departures from the detail specifications as may be required to
permit improvements in the performance, reliability, or manufacturability of its products. Before placing an order, the user is cautioned to verify that
the information being relied upon is current.
Allegro’s products are not to be used in life support devices or systems, if a failure of an Allegro product can reasonably be expected to cause the
failure of that life support device or system, or to affect the safety or effectiveness of that device or system.
The information included herein is believed to be accurate and reliable. However, Allegro MicroSystems, LLC assumes no responsibility for its
use; nor for any infringement of patents or other rights of third parties which may result from its use.
Copyright ©2005-2013, Allegro MicroSystems, LLC
For the latest version of this document, visit our website:
www.allegromicro.com
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