LNBH21 LNB SUPPLY AND CONTROL IC WITH STEP-UP CONVERTER AND I2C INTERFACE COMPLETE INTERFACE BETWEEN LNB AND I2CTM BUS BUILT-IN DC/DC CONTROLLER FOR SINGLE 12V SUPPLY OPERATION AND HIGH EFFICIENCY (Typ. 94% @ 750mA) TWO SELECTABLE OUTPUT CURRENT LIMIT (450mA / 750mA) BOTH COMPLIANT WITH EUTELSAT AND DIRECT OUTPUT VOLTAGE SPECIFICATION ACCURATE BUILT-IN 22KHz TONE OSCILLATOR SUITS WIDELY ACCEPTED STANDARDS FAST OSCILLATOR START-UP FACILITATES DiSEqCTM ENCODING BUILT-IN 22KHz TONE DETECTOR SUPPORTS BI-DIRECTIONAL DiSEqCTM2.0 SEMI-LOWDROP POST REGULATOR AND HIGH EFFICIENCY STEP-UP PWM FOR LOW POWER LOSS: Typ. 0.56W @ 125mA TWO OUTPUT PINS SUITABLE TO BYPASS THE OUTPUT R-L FILTER AND AVOID ANY TONE DISTORSION (R-L FILTER AS PER DiSEqC 2.0 SPECs, see application circuit on pag. 5) CABLE LENGTH DIGITAL COMPENSATION OVERLOAD AND OVER-TEMPERATURE INTERNAL PROTECTIONS PowerSO-20 OVERLOAD AND OVER-TEMPERATURE I2C DIAGNOSTIC BITs LNB SHORT CIRCUIT SOA PROTECTION WITH I2C DIAGNOSTIC BIT +/- 4KV ESD TOLERANT ON INPUT/ OUTPUT POWER PINS DESCRIPTION Intended for analog and digital satellite STB receivers/SatTV, sets/PC cards, the LNBH21 is a monolithic voltage regulator and interface IC, assembled in POWER SO-20, specifically designed to provide the 13/18V power supply and the 22KHz tone signalling to the LNB downconverter in the antenna or to the multiswitch box. In this application field, it offers a complete solution with extremely low component count, low power dissipation together with simple design and I2CTM standard interfacing. BLOCK DIAGRAM LNBH21 Gate Sense Step-up PWM Controller Vup-Feedback VoTX Vup VoRX Vcc Preregul.+ U.V.lockout +P.ON res. Byp SDA SCL Linear Post-reg +Modulator +Protections V Select Diagnostics Tone Detector TEN April 2004 EXTM IC interf. Enable ADDR DSQIN ISEL DETIN 22KHz Oscill. DSQOUT 1/20 LNBH21 ORDERING CODES TYPE PowerSO-20 (Tube) PowerSO-20 (Tape & Reel) LNBH21 LNBH21PD LNBH21PD-TR ABSOLUTE MAXIMUM RATINGS Symbol Parameter Value Unit VCC DC Input Voltage -0.3 to 16 V VUP DC Input Voltage -0.3 to 25 V IO Output Current Internally Limited mA DC Output Pins Voltage -0.3 to 25 V Logic Input Voltage (SDA, SCL, DSQIN, ISEL) -0.3 to 7 V Detector Input Signal Amplitude -0.3 to 2 VPP VOH Logic High Output Voltage (DSQOUT) -0.3 to 7 V IGATE Gate Current 400 mA -0.3 to 1 V VOTX/RX VI VDETIN VSENSE Current Sense Voltage VADDRESS Address Pin Voltage -0.3 to 7 V Tstg Storage Temperature Range -40 to +150 C Top Operating Junction Temperature Range -40 to +125 C Absolute Maximum Ratings are those values beyond which damage to the device may occur. Functional operation under these condition is not implied. THERMAL DATA Symbol Rthj-case Parameter Thermal Resistance Junction-case PIN CONFIGUARATION (top view) 2/20 Value Unit 2 C/W LNBH21 TABLE A: PIN CONFIGURATIONS PIN N SYMBOL NAME 18 VCC 17 16 GATE SENSE 19 VUP 2 VORX 12 SDA Output Port during 22KHz Tone RX Serial Data 13 SCL Serial Clock 14 DSQIN DiSEqC Input 9 DETIN Tone Detector Input Supply Input External Switch Gate Current Sense Input Step-up Voltage FUNCTION 8V to 15V IC supply. A 220F bypass capacitor to GND with a 470nF (ceramic) in parallel is recommended External MOS switch Gate connection of the step-up converter DC/DC Current Sense comparator input. Connected to current sensing resistor Input of the linear post-regulator. The voltage on this pin is monitored by internal step-ut controller to keep a minimum dropout across the linear pass transistor RX Output to the LNB in DiSEqC 2.0 application. See truth tables for voltage selections on page 8 and description on page 5. Bidirectional data from/to I2C bus. 5 EXTM 1, 6, 10, 11, 20 8 3 GND Ground Clock from I2C bus. When the TEN bit of the System Register is LOW, this pin will accept the DiSEqC code from the main controller. The LNBH21 will use this code to modulate the internally generated 22kHz carrier. Set to GND this pin if not used. 22kHz Tone Detector Input. Must be AC coupled to the DiSEcQ 2.0 bus. Open drain output of the tone Detector to the main controller for DiSEcQ 2.0 data decoding. It is LOW when tone is detected. External Modulation Input acts on VOTX. Needs DC decoupling to the AC source. If not used, can be left open. Pins Connected to Ground. BYP ISEL Bypass Capacitor Current Limit Select Needed for internal preregulator filtering Set high or floating for Iout<=750mA, connect to ground for 15 DSQOUT DiSEqC Output External Modulator IOUT 450mA. 4 VOTX 7 ADDR Output Port during 22KHz Tone TX Address Setting Output of the linear post-regulator/modulator to the LNB. See truth tables for voltage selections. Four I2C bus addresses available by setting the Address Pin level voltage. See address pin characteristics table. 3/20 LNBH21 TYPICAL APPLICATION CIRCUITS Application Circuit for DiSEqC 1.x and Output Current < 450 mA D1 1N4001 Ferrite Bead Filter F1 suggested part number: IC1 MURATA BL01RN1-A62 Panasonic EXCELS A35 F1 Vup C9 100F IC2 STS4DNFS30L ISEL 3 19 C2 220F 2 C3(***) 470nF Ceramic VoRX 4 GATE LNBH21 D2(***) BAT43 C8(***) 10nF 16 9 SENSE Rsc 0.1 to LNB VoTX 17 L1=22H Set TTX=1 C4(***) 470nF Ceramic (**) DETIN Byp 8 C5 470nF 18 C1 220F Vin 12V SDA SCL 7 13 0<VADDR<VBYP Address 14 Tone Enable EXTM 5 12 GND DSQIN(**) 15 DSQOUT Full Application Circuit for Bi-directional DiSEqC 2.0 and Output Current up to 750mA F1 suggested part number: MURATA BL01RN1-A62 Panasonic EXCELS A35 D2 1N4001 Axial Ferrite Bead Filter Floating or V>3.3V IC1 F1 Higher current limit ISEL Vup C2 220F D1 1N5821 or STPS3L40A C9 100F Lower current limit C3(***) 470nF Ceramic GND VoTX D4(***) BAT43 C8(***) 100nF MOS STN4NF03L 270H to LNB Gate VoRX LNBH21 Sense L1=22H C7(***) 100nF D3(***) BAT43 15 ohm (*) see note (**) DETIN C6 10nF Rsc 0.05 Byp C5 470nF Vcc Vin 12V C1 220F C4(***) 470nF Ceramic SDA EXTM SCL ADDRESS DSQIN (**) GND 0<VADDR<VBYP DSQOUT 22KHz Tone Enable (*) Filter to be used according to EUTELSAT recommendation to implement the DiSEqCTM 2.0, (see DiSEqCTM implementation on page 8). If bidirectional DiSEqCTM 2.0 is not implemented it can be removed both with C8 and D4. (**) Do not leave these pins floating if not used. (***) To be soldered as close as possible to relative pins. -C8 and D3,4 are needed only to protect the output pins from any negative voltage spikes during high speed voltage transitions. 4/20 LNBH21 APPLICATION INFORMATION This IC has a built in DC/DC step-up controller that, from a single supply source ranging from 8 to 15V, generates the voltages (VUP) that let the linear post-regulator to work at a minimum dissipated power of 1.65W typ. @ 750mA load (the linear regulator drop voltage is internally kept at: VUP-VO=2.2V typ.). An UnderVoltage Lockout circuit will disable the whole circuit when the supplied VCC drops below a fixed threshold (6.7V typically). The internal 22KHz tone generator is factory trimmed in accordance to the standards, and can be controlled either by the I2CTM interface or by a dedicated pin (DSQIN) that allows immediate DiSEqCTM data encoding (*). When the TEN (Tone ENable) I2C bit it is set to HIGH, a continuous 22KHz tone is generated on the output regardless of the DSQIN pin logic status. The TEN bit must be set LOW when the DSQIN pin is used for DiSEqCTM encoding. The fully bi-directional DiSEqCTM 2.0 interfacing is completed by the built-in 22KHz tone detector. Its input pin (DETIN) must be AC coupled to the DiSEqCTM bus, and the extracted PWK data are available on the DSQOUT pin (*). To comply to the bi-directional DiSEqCTM 2.0 bus hardware requirements an output R-L filter is needed. The LNBH21 is provided with two output pins: the VOTX to be used during the tone transmission and the VORX to be used when the tone is received. This allows the 22KHz Tone to pass without any losses due to the R-L filter impedance (see DiSeqC 2.0 application circuit on page 5). In DiSeqC 2.0 applications during the 22KHz transmission activated by DSQIN pin (or TEN I2C bit), the VOTX pin must be preventively set ON by the TTX I2C bit and, both the 13/18V power supply and the 22KHz tone, are provided by mean of VOTX output. As soon as the tone transmission is expired, the VOTX must be set to OFF by setting the TTX I2C bit to zero and the 13/18V power supply is provided to the LNB by the VORX pin through the R-L filter. When the LNBH21 is used in DiSeqC 1.x applications the R-L filter is not required (see DiSeqC 1.x application circuit on pag.5), the TTX I2C bit must be kept always to HIGH so that, the VOTX output pin can provide both the 13/18V power supply and the 22KHz tone, enabled by DSQIN pin or by TEN I2C bit. All the functions of this IC are controlled via I2C TM bus by writing 6 bits on the System Register (SR, 8 bits). The same register can be read back, and two bits will report the diagnostic status. When the IC is put in Stand-by (EN bit LOW), the power blocks are disabled. When the regulator blocks are active (EN bit HIGH), the output can be logic controlled to be 13 or 18 V by mean of the VSEL bit (Voltage SELect) for remote controlling of non-DiSEqC LNBs. Additionally, the LNBH21 is provided with the LLC I2C bit that increase the selected voltage value (+1V when VSEL=0 and +1.5V when VSEL=1) to compensate for the excess voltage drop along the coaxial cable (LLC bit HIGH). By mean of the LLC bit, the LNBH21 is also compliant to the American LNB power supply standards that require the higher output voltage level to 19.5V (typ.) (instead of 18V), by simply setting the LLC=1 when VSEL=1. In order to improve design flexibility and to allow implementation of newcoming LNB remote control standards, an analogic modulation input pin is available (EXTM). An appropriate DC blocking capacitor must be used to couple the modulating signal source to the EXTM pin. Also in this case, the VOTX output must be set ON during the tone transmission by setting the TTX bit high. When external modulation is not used, the relevant pin can be left open. The current limitation block is SOA type and it is possible to select two current limit thresholds, by the dedicated ISEL pin. The higher threshold is in the range of 750mA to 1A if the ISEL is left floating or connected a voltage > 3.3V. The lower threshold is in the range of 450mA to 700mA when the ISEL pin is connected to ground. When the output port is shorted to ground, the SOA current limitation block limits the short circuit current (ISC) at typically 400mA or 200mA respectively for VO 13V or 18V, to reduce the power dissipation. Moreover, it is possible to set the Short Circuit Current protection either statically (simple current clamp) or dynamically by the PCL bit of the I2C SR; when the PCL (Pulsed Current Limiting) bit is set to LOW, the overcurrent protection circuit works dynamically, as soon as an overload is detected, the output is shut-down for a time TOFF, typically 900ms. Simultaneously the OLF bit of the System Register is set to HIGH. After this time has elapsed, the output is resumed for a time TON=1/10TOFF (typ.). At the end of TON, if the overload is still detected, the protection circuit will cycle again through TOFF and TON. At the end of a full TON in which no overload is detected, normal operation is resumed and the OLF bit is reset to LOW. Typical TON+TOFF time is 990ms and it is determined by an internal timer. This dynamic operation can greatly reduce the power dissipation in short circuit condition, still ensuring excellent power-on start up in most conditions. 5/20 LNBH21 However, there could be some cases in which an highly capacitive load on the output may cause a difficult start-up when the dynamic protection is chosen. This can be solved by initiating any power start-up in static mode (PCL=HIGH) and then switching to the dynamic mode (PCL=LOW) after a chosen amount of time. When in static mode, the OLF bit goes HIGH when the current clamp limit is reached and returns LOW when the overload condition is cleared. This IC is also protected against overheating: when the junction temperature exceeds 150C (typ.), the step-up converter and the linear regulator are shut off, and the OTF SR bit is set to HIGH. Normal operation is resumed and the OTF bit is reset to LOW when the junction is cooled down to 140C (typ.). (*): External components are needed to comply to bi-directional DiSEqCTM bus hardware requirements. Full compliance of the whole application with DiSEqCTM specifications is not implied by the use of this IC I2C BUS INTERFACE Data transmission from main P to the LNBH21 and viceversa takes place through the 2 wires I2C bus interface, consisting of the two lines SDA and SCL (pull-up resistors to positive supply voltage must be externally connected). DATA VALIDITY As shown in fig. 1, the data on the SDA line must be stable during the high period of the clock. The HIGH and LOW state of the data line can only change when the clock signal on the SCL line is LOW. START AND STOP CONDITIONS As shown in fig.2 a start condition is a HIGH to LOW transition of the SDA line while SCL is HIGH. The stop condition is a LOW to HIGH transition of the SDA line while SCL is HIGH. A STOP conditions must be sent before each START condition. BYTE FORMAT Every byte transferred to the SDA line must contain 8 bits. Each byte must be followed by an acknowledge bit. The MSB is transferred first. ACKNOWLEDGE The master (P) puts a resistive HIGH level on the SDA line during the acknowledge clock pulse (see fig. 3). The peripheral (LNBH21) that acknowledges has to pull-down (LOW) the SDA line during the acknowledge clock pulse, so that the SDA line is stable LOW during this clock pulse. The peripheral which has been addressed has to generate an acknowledge after the reception of each byte, otherwise the SDA line remains at the HIGH level during the ninth clock pulse time. In this case the master transmitter can generate the STOP information in order to abort the transfer. The LNBH21 won't generate the acknowledge if the VCC supply is below the Undervoltage Lockout threshold (6.7V typ.). TRANSMISSION WITHOUT ACKNOWLEDGE Avoiding to detect the acknowledge of the LNBH21, the P can use a simpler transmission: simply it waits one clock without checking the slave acknowledging, and sends the new data. This approach of course is less protected from misworking and decreases the noise immunity. Figure 1 : DATA VALIDITY ON THE I2C BUS 6/20 LNBH21 Figure 2 : TIMING DIAGRAM ON I2C BUS Figure 3 : ACKNOWLEDGE ON I2C BUS LNBH21 SOFTWARE DESCRIPTION INTERFACE PROTOCOL The interface protocol comprises: - A start condition (S) - A chip address byte = hex 10 / 11 (the LSB bit determines read(=1)/write(=0) transmission) - A sequence of data (1 byte + acknowledge) - A stop condition (P) CHIP ADDRESS S MSB 0 0 0 1 0 0 DATA 0 LSB MSB R/W ACK LSB ACK P ACK= Acknowledge; S = Start ; P = Stop; R/W = Read/Write SYSTEM REGISTER (SR, 1 BYTE) MSB R, W PCL R, W TTX R, W TEN R, W LLC R, W VSEL R, W EN R OTF LSB R OLF R,W = read and write bit; R = Read-only bit All bits reset to 0 at Power-On 7/20 LNBH21 TRANSMITTED DATA (I2C BUS WRITE MODE) When the R/W bit in the chip address is set to 0, the main P can write on the System Register (SR) of the LNBH21 via I2C bus. Only 6 bits out of the 8 available can be written by the P, since the remaining 2 are left to the diagnostic flags, and are read-only. PCL TTX TEN LLC VSEL X OLF Function 0 0 1 X X 0 1 1 X X VO = 18V, VUP=20 V 1 0 1 X X VO = 14.25 V, VUP = 16.25 V 1 1 1 X X VO = 19.5 V, VUP = 21.5 V 1 1 X X X X 1 X X X 1 X X X 1 1 0 X X X X X X 22KHz is controlled by DSQIN pin 22KHz tone is ON, DSQIN pin disabled VORX output is ON, output voltage controlled by VSEL and LLC VOTX output is ON, 22KHz controlled by DSQIN or TEN, output voltage level controlled by VSEL and LLC Pulsed (dynamic) current limiting is selected Static current limiting is selected Power blocks disabled 0 0 1 X OTF VO = 13.25 V, VUP = 15.25 V 0 1 1 EN X X X= don't care. Values are typical unless otherwise specified RECEIVED DATA (I2C bus READ MODE) The LNBH21 can provide to the Master a copy of the SYSTEM REGISTER information via I2C bus in read mode. The read mode is Master activated by sending the chip address with R/W bit set to 1. At the following master generated clocks bits, the LNBH21 issues a byte on the SDA data bus line (MSB transmitted first). At the ninth clock bit the MCU master can: - acknowledge the reception, starting in this way the transmission of another byte from the LNBH21; - no acknowledge, stopping the read mode communication. While the whole register is read back by the P, only the two read-only bits OLF and OTF convey diagnostic informations about the LNBH21. Values are typical unless otherwise specified. PCL TTX TEN LLC VSEL EN OTF OLF TJ<140C, normal operation 0 These bits are read exactly the same as they were left after last write operation Function TJ>150C, power block disabled 1 0 IOUT<IOMAX, normal operation 1 IOUT>IOMAX, overload protection triggered Values are typical unless otherwise specified POWER-ON I2C INTERFACE RESET The I2C interface built in the LNBH21 is automatically reset at power-on. As long as the VCC stays below the UnderVoltage Lockout threshold (6.7V typ.), the interface will not respond to any I2C command and the System Register (SR) is initialized to all zeroes, thus keeping the power blocks disabled. Once the VCC rises above 7.3V typ, the I2C interface becomes operative and the SR can be configured by the main P. This is due to 500mV of hysteresis provided in the UVL threshold to avoid false retriggering of the Power-On reset circuit. ADDRESS PIN Connecting this pin to GND the Chip I2C interface address is 0001000, but, it is possible to choice among 4 different addresses simply setting this pin at 4 fixed voltage levels (see table on page 10). 8/20 LNBH21 DiSEqCTM IMPLEMENTATION The LNBH21 helps the system designer to implement the bi-directional (2.0) DiSEqC protocol by allowing an easy PWK modulation/demodulation of the 22KHz carrier. The PWK data are exchanged between the LNBH21 and the main P using logic levels that are compatible with both 3.3 and 5V microcontrollers. This data exchange is made through two dedicated pins, DSQIN and DSQOUT, in order to maintain the timing relationships between the PWK data and the PWK modulation as accurate as possible. These two pins should be directly connected to two I/O pins of the P, thus leaving to the resident firmware the task of encoding and decoding the PWK data in accordance to the DiSEqC protocol. Full compliance of the system to the specification is thus not implied by the bare use of the LNBH21. The system designer should also take in consideration the bus hardware requirements; that can be simply accomplished by the R-L termination connected on the VO pins of the LNBH21, as shown in the Typical Application Circuit on page 4. To avoid any losses due to the R-L impedance during the tone transmission, the LNBH21 has dedicated output (VOTX) that, in a DiSEqC 2.0 application, is connected after the filter and must be enabled by setting the TTX SR bit HIGH only during the tone transmission (see DiSEqC 2.O operation description on page 2). Unidirectional (1.x) DiSEqC and non-DiSEqC systems normally don't need this termination, and the VOTX pin can be directly connected to the LNB supply port of the Tuner (see DiSeqC 1.x application circuit on pag.4). There is also no need of Tone Decoding, thus DETIN and DSQOUT pins can be left unconnected and the Tone is provided by the VOTX. 9/20 LNBH21 ELECTRICAL CHARACTERISTICS FOR LNBP SERIES (TJ = 0 to 85C, EN=1, TTX=0/1, DSQIN=LOW, LLC=TEN=PCL=VSEL=0, VIN=12V, IO=50mA, unless otherwise specified. See software description section for I2C access to the system register). Symbol Parameter Test Conditions Min. VIN Supply Voltage IO = 750 mA TEN=VSEL=LLC=1 II Supply Current VO Output Voltage VO Output Voltage VO Line Regulation VO Load Regulation EN=TEN=VSEL=LLC=1, NO LOAD EN=0 IO = 750 mA VSEL=1 LLC=0 LLC=1 IO = 750 mA VSEL=0 LLC=0 LLC=1 VIN1= 8 to 15V VSEL=0 VSEL=1 VSEL=0 or 1, IO = 50 to 750mA IMAX Output Current Limiting ISEL = Floating or V > 3.3V ISEL = GND Typ. 8 17.3 18.7 12.75 13.75 20 3.5 18 19.5 13.25 14.25 5 5 750 450 Max. Unit 15 V 40 7 18.7 20.3 13.75 14.75 40 60 200 mA 1000 700 V V mV mV mA ISC Output Short Circuit Current tOFF fTONE Dynamic Overload protection OFF Time Dynamic Overload protection ON Time Tone Frequency TEN=1 20 22 24 KHz ATONE Tone Amplitude TEN=1 0.55 0.72 0.9 VPP DTONE Tone Duty Cycle TEN=1 40 50 60 % Tone Rise and Fall Time TEN=1 5 8 15 s 400 mVPP tON tr, tf GEXTM External Modulation Gain VSEL=0 VSEL=1 PCL=0 Output Shorted 300 200 900 PCL=0 Output Shorted tOFF/10 VOUT/VEXTM, f = 10Hz to 50KHz VEXTM External Input Voltage AC Coupling ZEXTM External Modulation Impedance DC/DC Converter Switching Frequency Tone Detector Frequency Capture Range Tone Detector Input Amplitude Tone Detector Input Impedance DSQOUT Pin Logic LOW f = 10Hz to 50KHz Tone present IOL=2mA Tone absent VOH = 6V IIH DSQOUT Pin Leakage Current DSQIN Input Pin Logic LOW DSQIN Input Pin Logic HIGH DSQIN Pins Input Current VIH = 5V IOBK Output Backward Current EN=0, fSW fDETIN VDETIN ZDETIN VOL IOZ VIL VIH Temperature Shutdown Threshold TSHDN Temperature Shutdown Hysteresis TSHDN 10/20 mA ms ms 6 260 220 kHz 0.4Vpp sinewave 18 24 kHz fIN=22kHz sinewave 0.2 1.5 VPP 150 0.3 k 0.5 V 10 A 0.8 V 2 V A 15 VOBK = 18V -6 -15 mA 150 C 15 C LNBH21 GATE AND SENSE ELECTRICAL CHARACTERISTICS (TJ = 0 to 85C, VIN = 12V) Symbol Parameter Test Conditions RDSON-L Gate LOW RDSON IGATE= -100mA RDSON-H Gate HIGH RDSON IGATE= 100mA Min. Typ. Max. 4.5 VSENSE Current Limit Sense Voltage Unit 4.5 200 mV I2C ELECTRICAL CHARACTERISTICS (TJ = 0 to 85C, VI = 12V) Symbol Parameter Test Conditions VIL LOW Level Input Voltage SDA, SCL VIH HIGH Level Input Voltage SDA, SCL Typ. Max. Unit 0.8 V 2 Input Current SDA, SCL, VI = 0.4 to 4.5V VOL Low Level Output Voltage SDA (open drain), IOL = 6mA fMAX Maximum Clock Frequency SCL II Min. V -10 10 A 0.6 V 500 KHz ADDRESS PIN CHARACTERISTICS (TJ = 0 to 85C, VIN=12V) Symbol Parameter Test Conditions Min. Typ. Max. Unit VADDR-1 "0001000" Addr Pin Voltage 0 0.7 V VADDR-2 "0001001" Addr Pin Voltage 1.3 1.7 V VADDR-3 "0001010" Addr Pin Voltage 2.3 2.7 V VADDR-4 "0001011" Addr Pin Voltage 3.3 5 V 11/20 LNBH21 THERMAL DESIGN NOTES During normal operation, the LNBH21 device dissipates some power. At maximum rated output current (750mA), the voltage drop on the linear regulator lead to a total dissipated power that is typically 1.65W. The heat generated requires a suitable heatsink to keep the junction temperature below the over temperature protection threshold. Assuming a 45C temperature inside the Set-Top-Box case, the total Rthj-amb has to be less than 48C/W. While this can be easily achieved using a through-hole power package that can be attached to a small heatsink or to the metallic frame of the receiver, a surface mount power package must rely on PCB solutions whose thermal efficiency is often limited. The simplest solution is to use a large, continuous copper area of the GND layer to dissipate the heat coming from the IC body. Given an Rthj-case equal to 2C/W, a maximum of 46C/W are left to the PCB heatsink. This figure is achieved if a minimum of 6.5cm2 copper area is placed just below the IC body. This area can be the inner GND layer of a multi-layer PCB, or, in a dual layer PCB, an unbroken GND area even on the opposite side where the IC is placed. In figure 4, it is shown a suggested layout for the PSO-20 package with a dual layer PCB, where the IC exposed pad connected to GND and the square dissipating area are thermally connected through 32 vias holes, filled by solder. This arrangement, when L=25mm, achieves an Rthc-amb of about 32C/W. Different layouts are possible, too. Basic principles, however, suggest to keep the IC and its ground exposed pad approximately in the middle of the dissipating area; to provide as many vias as possible; to design a dissipating area having a shape as square as possible and not interrupted by other copper traces. Figure 4 : PowerSO-20 SUGGESTED PCB HEATSINK LAYOUT 12/20 LNBH21 TYPICAL CHARACTERISTICS (unless otherwise specified Tj = 25C) Figure 5 : Output Voltage vs Temperature Figure 8 : Load Regulation vs Temperature Figure 6 : Output Voltage vs Temperature Figure 9 : Load Regulation vs Temperature Figure 7 : Output Voltage vs Temperature Figure 10 : Supply Current vs Temperature 13/20 LNBH21 Figure 11 : Supply Current vs Temperature Figure 14 : Dynamic Overload Protection OFF Time vs Temperature Figure 12 : Supply Current vs Temperature Figure 15 : Output Current Limiting vs Temperature Figure 13 : Dynamic Overload Protection ON Time vs Temperature Figure 16 : Output Current Limiting vs Temperature 14/20 LNBH21 Figure 17 : Tone Frequency vs Temperature Figure 20 : Tone Rise Time vs Temperature Figure 18 : Tone Amplitude vs Temperature Figure 21 : Tone Fall Time vs Temperature Figure 19 : Tone Duty Cycle vs Temperature Figure 22 : Undervoltage Lockout Threshold vs Temperature 15/20 LNBH21 Figure 23 : Output Backward Current vs Temperature Figure 26 : 22kHz Tone Waveform VCC=12V, IO=50mA, EN=TEN=1 Figure 24 : DC/DC Converter Efficiency vs Temperature Figure 27 : DSQIN Tone Enable Transient Response VCC=12V, IO=50mA, EN=1, Tone enabled by DSQIN Pin Figure 25 : Current Limit Sense Voltage vs Temperature Figure 28 : DSQIN Tone Enable Transient Response VCC=12V, IO=50mA, EN=1, Tone enabled by DSQIN Pin 16/20 LNBH21 Figure 29 : DSQIN Tone Disable Transient Response VCC=12V, IO=50mA, EN=1, Tone enabled by DSQIN Pin 17/20 LNBH21 PowerSO-20 MECHANICAL DATA mm. DIM. MIN. inch TYP MAX. A MIN. TYP. MAX. 3.60 a1 0.10 0.1417 0.30 a2 0.0039 0.0118 0 0.0039 3.30 a3 0 0.1299 0.10 b 0.40 0.53 0.0157 0.0209 c 0.23 0.32 0.0090 0.0013 D (1) 15.80 16.00 0.6220 0.630 E 13.90 14.50 0.5472 0.5710 e 1.27 e3 11.43 E1 (1) 0.0500 0.4500 10.90 11.10 E2 0.4291 0.4370 0.0000 0.0039 0.0314 0.0433 2.90 G 0 0.10 0.80 1.10 h 0.1141 1.10 L N 0.0433 10 S 0 10 8 T 0 8 10.0 0.3937 (1) "D and E1" do not include mold flash or protusions - Mold flash or protusions shall not exceed 0.15mm (0.006") N R N a2 b A a1 e DETAIL A c DETAIL B E e3 D DETAIL A lea d 20 11 slug a3 DETAIL B E2 E1 0.35 Gage Plan e T - C- S L SEATING PLANE G C (COPLANARITY) 1 1 0 PSO20MEC h x 45 0056635 18/20 LNBH21 Tape & Reel PowerSO-20 MECHANICAL DATA mm. inch DIM. MIN. A TYP MAX. MIN. 330 MAX. 12.992 C 12.8 D 20.2 0.795 N 60 2.362 T 13.2 TYP. 0.504 30.4 0.519 1.197 Ao 15.1 15.3 0.594 0.602 Bo 16.5 16.7 0.650 0.658 Ko 3.8 4.0 0.149 0.157 Po 3.9 4.1 0.153 0.161 P 23.9 24.1 0.941 0.949 W 23.7 24.3 0.933 0.957 19/20 LNBH21 Information furnished is believed to be accurate and reliable. However, STMicroelectronics assumes no responsibility for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of STMicroelectronics. Specifications mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information previously supplied. STMicroelectronics products are not authorized for use as critical components in life support devices or systems without express written approval of STMicroelectronics. The ST logo is a registered trademark of STMicroelectronics All other names are the property of their respective owners (c) 2004 STMicroelectronics - All Rights Reserved STMicroelectronics GROUP OF COMPANIES Australia - Belgium - Brazil - Canada - China - Czech Republic - Finland - France - Germany - Hong Kong - India - Israel - Italy - Japan Malaysia - Malta - Morocco - Singapore - Spain - Sweden - Switzerland - United Kingdom - United States. http://www.st.com 20/20