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A8286 Dual LNB Supply and Control Voltage Regulator
Features and Benefits
2-wire serial I2CTM -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 1318 V output transition; reliably starts wide load range Push-pull output stage minimizes 1318 V and 1813 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 DiSEqCTM tone encoding, even at no-load Four methods of 22 kHz tone generation, via I2CTM data bits and/or external pin 22 kHz tone detector facilitates DiSEqCTM 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 DiSEqCTM tone output Cable disconnect diagnostic
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. The A8286 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(R) 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 DiSEqCTM 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.
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Package:
28 pin 5 mm x 5mm QFN/MLP (suffix ET)
Functional Block Diagram
VS
A
C2 100 F
Channel 1
L1 33 H
D1
L3 1H C6 1F
VDD
R4 R5
C5 100 F
C4 100 nF BOOST1 VCP1
D3 C
TDO1 EXTM1
LX1
GNDLX1
A B C D
Channel 1 of 2 channels shown. R8-C11 network is needed only when high inductive load is applied, such as ProBrand LNB. D3 and D4 are used for surge protection. Either C12 or C9 should be used, but not both.
A8286 Charge Pump VIN C1 100 nF VREG C3 220 nF DAC R2 R1 SDA SCL I2 C Compatible Interface Fault Monitor OCP1 OCP2 PNG1 PNG2 TSD VUV Fsw TCAP1 Clock Divider 22 kHz Oscillator TDO1 Tone Detect TDI1 C7 10 nF R3 Boost Converter Regulator Fsw
LNB Voltage Control
C12
D
TMode1 EXTM1
VPump
R6 15 LNB1 C8 D2 220 nF
R8 30 C11 0.68 F B
Wave Shape TCAP1 TGate1
Linear Stage
VOUT1 L2 220 H C9 220 nF
D
C13 10 nF
D4 C
IRQ
R7 100
C10 10 nF
PAD
GND
8286-DS, Rev. 3
A8286
Dual LNB Supply and Control Voltage Regulator
The device uses a 2-wire bidirectional serial interface, compatible with the I2CTM 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.
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.
Absolute Maximum Ratings
Characteristic Load Supply Voltage, VIN pin Output Current* Output Voltage; BFI, BFO, LNB, LX, and BOOST pins Output Voltage; VCP pin Logic Input Voltage, EXTM pin Logic Input Voltage, other pins Logic Output Voltage Operating Ambient Temperature Junction Temperature Storage Temperature TA TJ(max) Tstg VCP Symbol VIN IOUT Conditions Rating 16 Internally Limited -1 to 33 -1 to 41 -0.3 to 5 -0.3 to 7 -0.3 to 7 -20 to 85 150 -55 to 150 Units V A V V V V V C C 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 150C.
Package Thermal Characteristics*
Package ET RJA (C/W) 32 PCB 4-layer
* Additional information is available on the Allegro website.
Ordering Information Use the following complete part numbers when ordering:
Part Number A8286SETTR-TB
aContact Allegro bLeadframe
Packinga 7-in. reel, 1500 pieces/reel 12 mm carrier tape
Description ET package, MLP surface mount
for additional packing options.
plating 100% matte tin.
Allegro MicroSystems, Inc. 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
27 GNDLX1 23 GNDLX2 28 LNB1 22 LNB2 21 BOOST2 20 VCP2 19 TCAP2 PAD 18 NC 17 TDO2 16 EXTM2 15 TDI2 SDA 10 12 SCL NC 13 ADD 11 IRQ 14 8 9 25 VIN 26 LX1 24 LX2
BOOST1 VCP1 TCAP1 NC TDO1 EXTM1 TDI1
1 2 3 4 5 6 7
GND
Terminal List Table
Name GND ADD BOOST1 BOOST2 EXTM1 EXTM2 GND PAD GNDLX1 GNDLX2 IRQ LNB1 LNB2 LX1 LX2 NC SCL SDA TCAP1 TCAP2 TDI1 TDI2 TDO1 TDO2 VCP1 VCP2 VIN VREG Number - 11 1 21 6 16 8 Pad 27 23 14 28 22 26 24 4, 13, 18 12 10 3 19 7 15 5 17 2 20 25 9 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 I2CTM-compatible clock input I2CTM-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 Function Fused internally; connect to ground plane for thermal dissipation
VREG
(Top View)
Allegro MicroSystems, Inc. 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 = 25C, VIN = 8 to 16 V, unless noted otherwise1
Characteristics General Set-Point Accuracy, Load and Line Regulation Err IIN(Off) 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 Ripple and Noise on LNB Output, Peak-to-Peak2 Protection Circuitry 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 Cable Disconnect Set Cable Disconnect Current Source ILIMLNB tDIS VUVLO VIN(th) VUVLOHYS TJ TJ PNGSET PNGRESET PNGHYS VCAD VCADSET ICADSRC VLNB = 21.00 V, VBOOST = 22.8 V With respect to VLNB With respect to VLNB With respect to VLNB CADT bit = 1, ENB bit = 1, VSEL0 through VSEL3 = 1 VIN falling VIN rising 800 40.0 7.05 7.40 - - - 77 82 - 22.0 20.16 1.0 900 48 7.35 7.70 350 165 20 85 90 5 22.8 21.00 1.75 1000 56.0 7.65 8.00 - - - 93 98 - 23.5 21.84 2.5 mA ms V V mV C C % % % V V mA IIN(On) Relative to selected VLNB target level, ILOAD = 0 to 500 mA ENB bit = 0, LNB output disabled, VIN = 12 V ENB bit = 1, LNB output enabled, ILOAD = 0 mA, VIN = 12 V -4.5 - - - 320 3.0 VBOOST - VLNB, no tone signal, ILOAD = 500 mA TCAP capacitor (C7) charging TCAP capacitor (C7) discharging For VLNB 13 18 V; CTCAP = 5.6 nF, ILOAD = 500 mA For VLNB 18 13 V; CLOAD = 100 F, ILOAD = 0 mA ENB bit = 0, VLNB = 33 V , BOOST capacitor (C5) fully charged 20 MHz bandwidth 600 -12.5 7.5 - - - - - - - 300 352 3.8 800 -10 10 500 12.5 1 30 4.5 12.0 20.0 600 384 4.8 1000 -7.5 12.5 - - 5 - % mA mA m kHz A mV A A s ms mA mVPP Symbol Test Conditions Min. Typ. Max. Units
RDS(on)BOOST ILOAD = 500 mA fSW ILIMSW VREG ICHG IDISCHG tr(VLNB) tf(VLNB) IRLNB Vrip,n(pp)
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Allegro MicroSystems, Inc. 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 (continued) at TA = 25C, VIN = 8 to 16 V, unless noted otherwise1
Characteristics Tone Tone Frequency Tone Amplitude, Peak-to-Peak Tone Duty Cycle Tone Rise Time Tone Fall Time EXTM Logic Input EXTM Input Leakage Tone Detector Tone Detect Input Amplitude Receive, Peak-toPeak Tone Detect Input Amplitude Transmit, Peakto-Peak Tone Reject Input Amplitude, Peak-to-Peak Frequency Capture Input Impedance2 TDO Output Voltage TDO Output Leakage I2CTM-Compatible Interface Logic Input (SDA,SCL) Low Level Logic Input (SDA,SCL) High Level Logic Input Hysteresis Logic Input Current Logic Output Voltage SDA and IRQ Logic Output Leakage SDA and IRQ SCL Clock Frequency Output Fall Time Bus Free Time Between Stop/Start Hold Time Start Condition Setup Time for Start Condition SCL Low Time SCL High Time Data Setup Time Data Hold Time Setup Time for Stop Condition VSCL(L) VSCL(H) VI2CIHYS II2CI Vt2COut(L) Vt2CLKG fCLK tfI2COut tBUF tHD:STA tSU:STA tLOW tHIGH tSU:DAT tHD:DAT tSU:STO Vt2COut(H) to Vt2COut(L) VI2CI = 0 to 7 V ILOAD = 3 mA Vt2COut = 0 to 7 V - 2.0 - -10 - - - - 1.3 0.6 0.6 1.3 0.6 100 0 0.6 - - 150 <1.0 - - - - - - - - - - - - 0.8 - - 10 0.4 10 400 250 - - - - - - 900 - V V mV A V A kHz ns s s s s s ns ns s VTDR(pp) VTDT(pp)Int VTDT(pp)Ext VTRI(pp) fTDI ZTDI VTDO(L) ITDOLKG Tone present, ILOAD = 3 mA Tone absent, VTDO = 7 V fTONE = 22 kHz sine wave, TMODE = 0 fTONE = 22 kHz sine wave, using internal tone (options 1 and 2, in figure 2) fTONE = 22 kHz sine wave, using external tone (options 3 and 4, in figure 2) fTONE = 22 kHz sine wave 600 mVpp sine wave 300 400 300 - 17.6 - - - - - - - - 8.6 - - - - - 100 26.4 - 0.4 10 mV mV mV mV kHz k V A fTONE VTONE(pp) DCTONE trTONE tfTONE VEXTM(H) VEXTM(L) IEXTMLKG ILOAD = 0 to 500 mA, CLOAD = 750 nF ILOAD = 0 to 500 mA, CLOAD = 750 nF ILOAD = 0 to 500 mA, CLOAD = 750 nF ILOAD = 0 to 500 mA, CLOAD = 750 nF 20 400 40 5 5 2.0 - -1 22 620 50 10 10 - - - 24 800 60 15 15 - 0.8 1 kHz mV % s s V V A Symbol Test Conditions Min. Typ. Max. Units
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Allegro MicroSystems, Inc. 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 (continued) at TA = 25C, VIN = 8 to 16 V, unless noted otherwise1
Characteristics I2CTM Address Setting ADD Voltage for Address 0001,000 ADD Voltage for Address 0001,001 ADD Voltage for Address 0001,010 ADD Voltage for Address 0001,011
1Operation
Symbol Address1 Address2 Address3 Address4
Test Conditions
Min. 0 1.3 2.3 3.3
Typ. - - - -
Max. 0.7 1.7 2.7 5.0
Units V V V V
at 16 V may be limited by power loss in the linear regulator. 2Guaranteed by design.
I2CTM Interface Timing Diagram
tSU:STA tHD:STA tSU:DAT tHD:DAT tSU:STO tBUF
SDA SCL
tLOW
tHIGH
Allegro MicroSystems, Inc. 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
Functional Description
Protection The A8286 has a wide range of protection features and fault diagnostics which are detailed in the Status Register section. Boost Converter/Linear Regulator Each channel contains a tracking current-mode boost converter and linear regulator. The boost converter tracks the requested LNB voltage to within 750 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 A8286 is not exceeded. The A8286 has internal pulse-by-pulse current limit 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. If the ODT timer is enabled, the IC will be shut down if the overcurrent condition lasts for more than 48 ms. If this occurs, the A8286 must be reenabled for normal operation. It is strongly recommended that the ODT timer be enabled at all times. The system should provide sufficient time between successive restarts to limit internal power dissipation; a period of 5 s is recommended. Each of the boost converters 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. At extremely light loads, and the boost converters operate 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 A8286 output will autorecover to their programmed levels.
Charge Pump. Each generates a supply voltage above the internal
tracking regulator output to drive the linear regulator control.
Slew Rate Control. During either start-up, or when the output
voltage on the BOOST or the LNB pins is changing, the output voltage rise and fall times can be set by the value selected for the external capacitor (C7) connected to the TCAP1 pin. Note that during start-up, the BOOST pin is precharged to the input voltage minus a diode drop. As a result, the slew rate control occurs from this point. The rating for C7, CTCAP , can be calculated using the following formula: CTCAP = (ITCAP x 6) / SR where SR (V/s) is the required slew rate. The minimum value for CTCAP is 2.2 nF. Using the recommended value of CTCAP , 5.6 nF, this calculates to a slew rate of 10.7 V/ms. Modulation is unaffected by the choice of C7. If it is not required to limit the LNB output voltage rise and fall times, then C7 must have a value of at least 2.2 nF to minimize output noise. This information applies to channel 2, as well as to channel 1 of the A8286.
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.
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A8286
Dual LNB Supply and Control Voltage Regulator
ODT (Overcurrent Disable Time) This function should be enabled at all times. If the ODT function is enabled and the LNB output current exceeds 900 mA, typical, for more than 48 ms, then the LNB output will be disabled and the ODT 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 ODT 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 transient 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 with the ODT timer enabled. The 8286 can also provide up to 700 mA per channel individually, or 1.1 A to both channels simultaneously, for a period of up to 2 s. Operating at this level for a longer period is not recommended.
DC current The A8286 can handle up to 650 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
Transmit Option (Fig. 1) TMODE TGATE 1 1 Control 0/1 2 1 1 3 0 Control 0/1 4 0 1 Control gated 22 kHz logic signal 300 At least one must be 0 to prevent tone transmission Receive n.a. 0 n.a. 1
EXTM
1
22 kHz Control logic 0/1 signal, continuous
Guaranteed Detection Threshold (mVPP) Rejection Threshold (mVPP)
400
400
300
300
400
100
100
100
100
100
100
ODT (Overcurrent Disable Timing) Mode Timing Diagram
ODT Timer Mode internal enabling signal
+A 900 mA, typ. per channel 700 mA for one channel, and 1.1 A total current 650 mA for one channel, and 950 mA total current Safe Operating Area 0 tDIS 2000 ms Start-up Continuous Operation tDIS Continuous Operation LNB Reconfiguration Short Circuit tDIS
IOUT(LNBX), per channel
t
Figure 1. ODT (Overcurrent Disable Timing) Mode Timing Diagram
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A8286
Dual LNB Supply and Control Voltage Regulator
Tone Generation The A8286 solution offers four options for tone generation, providing maximum flexibility to cover every application. The EXTM pins (external modulation), in conjunction with the I2CTM 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).
EXTM TMODE TGATE Tone (LNB Ref)
LNB (V)
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. I2CTM-Compatible Interface This is a serial interface that uses two bus lines, SCL and SDA, to access the internal Control and Status registers of the A8286. Data is exchanged between a microcontroller (master) and the A8286 (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 I2CTMcompatible 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
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)
LNB (V)
Option 4 - Use external tone. Figure 2. Options for tone generation
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A8286
Dual LNB Supply and Control Voltage Regulator
A8286 always responds by resetting the data transfer sequence. 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 four 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 A8286 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 A8286 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. During a data read, the A8286 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 A8286 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 A8286 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 A8286 stops sending data and waits for a stop signal.
acknowledge from LNBR Start SDA 0 0 0 Address 1 0 A1 A0 W 0 AK I1 I0 D5 Control Data D4 D3 D2 D1 D0
acknowledge from LNBR Stop AK
SCL
1
2
3
4
5
6
7
8
9
Write to Register
acknowledge from LNBR Start SDA 0 0 0 Address 1 0 A1 A0 R 1 AK D7 D6 Status Register 1 D5 D4 D3 D2 D1 D0 NAK no acknowledge from master Stop
SCL
1
2
3
4
5
6
7
8
9
Read One Byte from Register
acknowledge from LNBR Start SDA 0 0 0 Address 1 0 A1 A0 R 1 AK D7 Status Data in Register 1 D6 D5 D4 D3 D2 D1 D0 AK acknowledge from LNBR Status Data in Register 2 D3 D2 D1 D0 NAK no acknowledge from master Stop
SCL
1
2
3
4
5
6
7
8
9
Read Multiple Bytes from Register
Figure 3. I2CTM Interface. Read and write sequences.
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A8286
Dual LNB Supply and Control Voltage Regulator
Interrupt Request
The A8286 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 I2CTM-compatible devices to request attention from the master controller. The IRQ output becomes active when either the A8286 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 I2CTM master addresses the A8286 with the Read/Write bit set (causing a read). Fault conditions are indicated by the TSD, VUV, and OCP bits (when ODT is set to 1) and are latched in the Status register. See the Status register section for full description. The OCP (with ODT= 0), 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 the status register to determine which device is requesting attention. The A8286 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 A8286 is fully active with no fault conditions. When VIN is initially applied, the I2CTM-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 A8286 acknowledges the address, the IRQ flag is reset. After the master reads the status registers, the registers are updated with the VUV reset.
Start SDA 0 0 0
Address 1 0 A1 A0
R 1 AK D7 D6
Status Register 1 D5 D4 D3 D2 D1 D0 NAK
Stop
SCL
1
2
3
4
5
6
7
8
9
IRQ
Fault Event
Read after Interrupt
Reload Status Register
Figure 4. I2CTM Interface. Read sequences after interrupt request.
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A8286
Dual LNB Supply and Control Voltage Regulator
Control Registers (I2CTM-Compatible Write Register)
All main functions of the A8286 are controlled through the I2CTM-compatible interface via the 8-bit Control registers. As the A8286 contains numerous control options, as well as featuring two channels, it is necessary to have four 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 Registers with Address (I1, I0) = 00 and 01
Name Bit 0 1 2 3 Channel 1 (Address: I1, I0 = 00) VSEL01 VSEL11 VSEL21 VSEL31 Channel 2 (Address: I1, I0 = 01) VSEL02 VSEL12 VSEL22 VSEL32 0: LNBx = Low range 1: LNBx = High range 0: Overcurrent disable time off 1: Overcurrent disable time on (setting ODT on at all times is recommended) 0: Disable LNBx Output 1: Enable LNBx Output Address Bit 6 I0 I0 Channel 1: 0 Channel 2: 1 Address Bit 7 I1 I1 Channel 1: 0 Channel 2: 0 Setting
See table 4, Output Voltage Amplitude Selection
4
ODT1
ODT2
5
ENB1
ENB2
Bit 0 Bit 1 Bit 2 Bit 3
VSEL0x VSEL1x VSEL2x VSEL3x
Bit 4
ODTx
Bit 5 Bit 6 Bit 7
ENBx I0 I1
These three bits provide incremental control over the voltage on the LNBx 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 LNBx 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 VSEL2x, VSEL1x and VSEL0x control register bits. Enables the overcurrent disable timer. When set to 1, and an overcurrent occurs for longer than the detection time, the LNBx ouput on the channel is disabled. It is highly recommended that the ODT function be enabled at all times. (When set to 0, if an overcurrent occurs, the LNBx output will operate in current limit indefinitely.) Enables the LNBx output. When set to 1 the LNBx output is switched on. When set to 0, the LNBx output is disabled. Address Address
Allegro MicroSystems, Inc. 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
Table 3. Control Registers with Address (I1, I0) = 10 and 11
Name Bit 0 1 2 3 4 5 6 Channel 1 (Address: I1, I0 = 10)
TMODE1 TGATE1 CADT1 - - - I0
Channel 2 (Address: I1, I0 = 11)
TMODE2 TGATE2 CADT2 - - - I0
Setting
0: External Tone 1: Internal Tone 0: Tone Gated Off 1: Tone Gated On 0: Cable Disconnect Test Off 1: Cable Disconnect Test On Not Used Not Used Not Used Address Bit Channel 1: 0 Channel 2: 1 Address Bit Channel 1: 1 Channel 2: 1
7
I1
I1
Bit 0
Bit 1
Bit 2
Bit 3 Bit 4 Bit 5 Bit 6 Bit 7
TMODEx ToneMode. 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 LNBx output. A 0 selects the external tone and a 1 selects the internal tone. See the Tone Generation section for more information TGATEx Tone Gate. Allows either the internal or external 22 kHz tone signals to be gated, unless the EXTMx is selected for gating. When set to 0, the selected tone (via TMODEx) is off. When set to 1, the selected tone is on. See Tone Generation Section for more information. CADTx 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 coaxial cable is connected and the CAD bit in the Status register is set to 0. - Not Used. - Not Used. - Not Used. I0 Address. I1 Address.
Allegro MicroSystems, Inc. 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
Table 4. Output Voltage Amplitude Selection
VSEL3x 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 VSEL2x 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 VSEL1x 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 VSEL0x 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 LNB (V) 12.709 13.042 13.375 13.709 14.042 14.375 14.709 15.042 18.042 18.375 18.709 19.042 19.375 19.709 20.042 20.375
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A8286
Dual LNB Supply and Control Voltage Regulator
Status Registers (I2CTM-Compatible Read Register)
The main fault conditions: overcurrent (OCP, with overcurrent disable timer, ODT enabled), 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 A8286 is read by the I2CTM master, assuming the fault has been resolved. The current status of each LNB output is indicated by the disable bit, DIS, for that channel. A DIS bit is set when either a fault occurs or if the LNB is disabled intentionally. These bits are latched and are 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 I2CTM read sequence. In addition, the overcurrent bit (OCP) can be reset without an I2CTM read, if the overcurrent disable timer (ODT) is
disabled. Table 5 summarizes the condition of each bit when set and how it is reset. As the A8286 has a comprehensive set of status reporting bits, it is necessary to have two Status registers. When performing a 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 CAD1, CAD2 DIS1, DIS2 Function Cable disconnected LNB disabled, either intentionally or due to fault Overcurrent with overcurrent disable timer set to 1 Overcurrent with overcurrent disable timer set to 0 Power not good Tone detect Thermal shutdown Undervoltage Set Non-latched Latched Latched Non-latched Non-latched Non-latched Latched Latched Reset Condition Cable disconnect test off or cable connected LNB enabled and no fault I2CTM read and fault removed Overcurrent removed LNB volts in range Tone removed I2CTM read and fault removed I2CTM read and fault removed
OCP1, OCP2
PNG1, PNG2 TDET1, TDET2 TSD VUV
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A8286
Dual LNB Supply and Control Voltage Regulator
Table 6. Status Register 1
Bit 0 1 2 3 4 5 6 7 Name DIS1 DIS2 OCP1 OCP2 PNG1 PNG2 TSD VUV Function LNB output disabled (Channel 1) LNB output disabled (Channel 2) Overcurrent (Channel 1) Overcurrent (Channel 2) Power Not Good (Channel 1) Power Not Good (Channel 2) Thermal Shutdown VIN Undervoltage
Bit 0
DIS1
Bit 1 Bit 2
DIS2 OCP1
Bit 3 Bit 4 Bit 5 Bit 6
OCP1 PNG1 PNG2 TSD
Bit 7
VUV
LNB Output Disabled. DIS is used to indicate the current condition of the LNB output for channel 1. At power-on, or if a fault condition occurs, DIS1 is set. This bit changing to 1 does not cause the IRQ to activate because the LNB output may be disabled intentionally by the I2CTM master. This bit will be reset at the end of a write sequence if the LNB output is enabled. See description for DIS1. This indicates status for channel 2. Overcurrent. If the LNB output detects an overcurrent condition for greater than the detection time, and the overcurrent detection timer, ODT, is enabled, the LNB output will be disabled. The OCP bit will be set to indicate that an overcurrent has occurred and the disable bit, DIS1, 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. If the overcurrent timer is not enabled, the device operates in current limit indefinitely and the OCP bit will be set. If the overcurrent condition is removed, the OCP bit will automatically be reset. Note that if the overcurrent remains long enough, and a thermal shutdown occurs, the LNB output will be disabled and the TSD bit set. See description for OCP1. This indicates status for channel 2. Power Not Good. Set to 1 when the LNB output is enabled and the LNB voltage is below 85 % of the programmed voltage. PNG1 is reset when the LNB volts are within 90 % of the programmed LNB voltage. See description for PNG1. This indicates status for channel 2. Thermal shutdown. 1 indicates that the A8286 has detected an overtemperature condition and has disabled the LNB outputs. The disable bits, DISx, 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 A8286 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 bits, DISx, will also be set, and the A8286 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.
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A8286
Dual LNB Supply and Control Voltage Regulator
Table 7. Status Register 2
Bit 0 1 2 3 4 5 6 7 Name CAD1 CAD2 TDET1 TDET2 - - - - Function Cable Disconnected (Channel 1) Cable Disconnected (Channel 2) Tone Detect (Channel 1) Tone Detect (Channel 2) Not Used Not Used Not Used Not Used
Bit 0
CAD1
Bit 1 Bit 2
CAD2 TDET1
Bit 3 TDET2 Bits 4 to 7
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 BOOST1 and LNB1 output. If the LNB volts rise above 21 V, CAD1 will be set to 1. The CAD1 bit is reset if the LNB volts drop below 19.95 V. See description for CAD1. This indicates status for channel 2. Tone Detect. When tone is enabled by whatever option, or if a tone signal is received from the LNB, TDET1 will be set to 1 if the tone appears at the LNB1 output. When the tone is disabled and no tone is received from the LNB, TDET1 is reset. See description for CAD1. This indicates status for channel 2. Not used.
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A8286
Dual LNB Supply and Control Voltage Regulator
Table 8. Component Selection Tablea
Component C3 C8, C9b, C12b C1, C4 C2, C5 C7 C10, C13 Characteristics 220 nF, 10 VMIN, X5R or X7R, 0402 or 0603 220 nF, 50 V, X5R or X7R, 0805 100 nF, 50 V, X5R or X7R, 0603 100 F, 35 VMIN , ESR < 75 m, IRIPPLE > 800 mA 10 nF, 10 VMIN, X5R or X7R, 0402 or 0603 10 nF, 50 V, X5R or X7R, 0402 or 0603 TDK: C2012X5R1E684K Murata: GRM21BR71E684KA88 Kemet: C0805C684K3PAC AVX: 08053D684KAT2A TDK: C3216X7R1E105K Murata: GRM31MR71E105KA01 Taiyo Yuden: TMK316BJ105KL-T Kemet: C1206C105K3RACTU Sanken: SFPB-74 Vishay: B340A-E3/5AT Diodes, Inc.: B340A-13-F Central Semi: CMSH3-40MA Diodes, Inc.: B140HW-7 Central Semi: CMMSH1-40 Vishay: 1.5KE24A-E3/54 Diodes, Inc.: 1.5KE24A-T TDK: TSL1112RA-330K2R3-PF Taiyo Yuden: LHLC10TB330K Coilcraft: DR0810-333L TDK: TSL0808RA-221KR54-PF Taiyo Yuden: LHLC08TB221K Coilcraft: DR0608-224L Kemet: LB3218-T1R0MK Murata: LQM31PN1R0M00L Taiyo Yuden: LB3218T1R0M TDK: MLP3216S1R0L ChemiCon: EKZE500ELL101MHB5D Nichicon: UHC1V101MPT Manufacturer and Device
C11
0.68 F, 25 VMIN, X5R or X7R, 0805
C6
1.0 F, 25 VMIN, X5R or X7R, 1206
D1, D3
Schottky diode, 40 V, 3 A, SMA
D2
Schottky diode, 40 V, 1 A, SOD-123 TVS, 24 V, 200 A, 1500 W; Use one TVS to provide surge protection up to 3 kV, and two TVSs for protection from 3 kV to 6 kV (1.2/50, 8/20, 12 A, per IEC 61000-4-5) 33 H, ISAT > 2.6 A, DCR < 90 m
D4
L1
L2
220 H, ISAT > 0.5 A, DCR < 0.8 m
L3
1 H, 1 A, DCR < 120 m, 1206
R1 to R5 R6 R7 R8
aComponents bEither
Determined by VDD, bus capacitance, etc. 15 , 1%, 1/8 W 100 , 1%, 1/8 W 30 , 1%, 1/8 W
for channel 1 and channel 2 are identical. C9 or C12 are used, but not both.
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A8286
Dual LNB Supply and Control Voltage Regulator
Package ET 28-Pin MLP/QFN
5.15 .203 4.85 .191 Preliminary dimensions, for reference only (reference JEDEC MO-220VHHD) Dimensions in millimeters U.S. Customary dimensions (in.) in brackets, for reference only Dimensions exclusive of mold flash, gate burrs, and dambar protrusions Exact case and lead configuration at supplier discretion within limits shown A Terminal #1 mark area B Exposed thermal pad (terminal #1 identifier appearance at supplier discretion) C Reference land pattern layout (reference IPC7351 QFN50P500X500X100-29V1M); 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) 28 1 2
A B
A 5.15 .203 4.85 .191
28X 0.08 [.003] C 28X 0.30 .012 0.18 .007 0.10 [.004] M C A B 0.05 [.002] M C 0.50 .020
SEATING PLANE 1.00 .039 0.80 .031 0.20 .008 REF 0.05 .002 0.00 .000
C
0.30 .012 NOM 1.15 .045 NOM 28 0.50 .020 NOM
3.15 NOM
.124
1 2 4X0.20 .008 MIN
C 4.8 .189 NOM
0.65 .026 0.45 .018 B 3.15 NOM .124
2 1 24X0.20 .008 MIN 3.15 NOM .124 4.8 .189 NOM R0.30 .012 REF 3.15 NOM 4X 0.20 .008 MIN .124 28
I2CTM is a trademark of Philips Semiconductors. DiSEqCTM is a trademark of Eutelsat S.A.
The products described here are manufactured under one or more U.S. patents or U.S. patents pending. Allegro MicroSystems, Inc. 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, Inc. 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 (c)2005, 2007, Allegro MicroSystems, Inc. For the latest version of this document, visit our website: www.allegromicro.com
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