19-2670; Rev 0; 10/02 80V Fault-Protected, 2Mbps, Low Supply Current CAN Transceivers The MAX3050 has an AutoShutdownTM function that puts the device into a 15A shutdown mode when the bus or CAN controller is inactive for 4ms or longer. The MAX3050/MAX3057 are available in an 8-pin SO package and are specified for operation from -40C to +125C. Features 80V Fault Protection for 42V Systems Four Operating Modes High-Speed Operation Up to 2Mbps Slope-Control Mode to Reduce EMI (40kbps to 500kbps) Standby Mode Low-Current Shutdown Mode AutoShutdown when Device Is Inactive (MAX3050) Automatic Wake-Up from Shutdown (MAX3050) Thermal Shutdown Current Limiting Fully Compatible with the ISO 11898 Standard* * Pending completion of testing. Ordering Information PART TEMP RANGE PIN-PACKAGE MAX3050ASA -40C to +125C 8 SO MAX3057ASA -40C to +125C 8 SO Pin Configuration TOP VIEW Applications TXD 1 Automotive Systems HVAC Controls GND Telecom 72V systems VCC 2 3 MAX3050 MAX3057 RXD 4 8 RS 7 CANH 6 CANL 5 SHDN SO AutoShutdown is a trademark of Maxim Integrated Products, Inc. Typical Operating Circuit VCC 120 0.1F VCC CANH TX0 TXD MAX3050 MAX3057 CANL RX0 RXD CAN CONTROLLER (100nF) SHDN 30pF RS GND 24k TO 180k GND 120 ( ) ARE FOR 3050 ONLY. ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com. 1 MAX3050/MAX3057 General Description The MAX3050/MAX3057 interface between the CAN protocol controller and the physical wires of the bus lines in a controller area network (CAN). They are primarily intended for automotive systems requiring data rates up to 2Mbps and feature 80V fault protection against short circuits in high-voltage power buses. They provide differential transmit capability to the bus and differential receive capability to the CAN controller. The MAX3050/MAX3057 have four modes of operation: high speed, slope control, standby, and shutdown. High-speed mode allows data rates up to 2Mbps. In slope-control mode, data rates are 40kbps to 500kbps, so the effects of EMI are reduced, and unshielded twisted or parallel cable can be used. In standby mode, the transmitters are shut off and the receivers are put into low-current mode. In shutdown mode, the transmitter and receiver are switched off. MAX3050/MAX3057 80V Fault-Protected, 2Mbps, Low Supply Current CAN Transceivers ABSOLUTE MAXIMUM RATINGS VCC to GND ............................................................ -0.3V to +6V TXD, RS, RXD, SHDN to GND ....................-0.3V to (VCC + 0.3V) CANH, CANL to GND..............................................-80V to +80V RXD Shorted to GND................................................. Continuous Continuous Power Dissipation (TA = +70C) 8-Pin SO (derate 5.9mW/C above +70C) .................470mW Operating Temperature Range .........................-40C to +125C Junction Temperature ......................................................+150C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10s) ................................+300C Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. DC ELECTRICAL CHARACTERISTICS (VCC = +5V 10%, RL = 60, RS = GND, TA = TMIN to TMAX. Typical values are at VCC = +5V and TA = +25C.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX 56 72 3.6 5.5 VRS = VCC 125 260 A SHDN = GND 15 30 A Dominant (Note 1) Supply Current IS Quiescent Current Standby Mode IQ Dominant no load 6 Recessive (Note 1) Recessive no load Shutdown Supply Current IQSHDN UNITS mA 5.5 Thermal-Shutdown Threshold 160 C Thermal-Shutdown Hysteresis 20 C TXD INPUT LEVELS High-Level Input Voltage VIH Low-Level Input Voltage VIL High-Level Input Current IIH Pullup Resistor 2 V 0.4 VTXD = VCC RINTXD V 1 A 20 k CANH, CANL TRANSMITTER Recessive Bus Voltage Off-State Output Leakage VCANH, VCANL ILO VTXD = VCC, no load 2 3 -2V < VCANH, VCANL < +7V SHDN = GND, VTXD = VCC -2 +1 -80V < VCANH, VCANL < +80V SHDN = GND, VTXD = VCC -4 +4 V mA CANH Output Voltage VCANH VTXD = 0 3.0 VCC V CANL Output Voltage VCANL VTXD = 0 0 2.0 V VTXD = 0 1.5 5 VTXD = 0, RL = 45 1.5 VTXD = VCC, no load -500 -200 Differential Output (VCANH - VCANL) VCANH, VCANL CANH Short-Circuit Current ISC VCANH = -5V CANL Short-Circuit Current ISC VCANL = 18V 2 _______________________________________________________________________________________ V +50 mV 200 mA mA 80V Fault-Protected, 2Mbps, Low Supply Current CAN Transceivers (VCC = +5V 10%, RL = 60, RS = GND, TA = TMIN to TMAX. Typical values are at VCC = +5V and TA = +25C.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS DC BUS RECEIVER (VTXD = VCC; CANH and CANL externally driven; -2V < VCANH, VCANL < +7V, unless otherwise specified) Differential Input Voltage (Recessive) VDIFF -7V < VCANH, VCANL < +12V -1.0 +0.5 V Differential Input Voltage (Dominant) VDIFF -7V < VCANH, VCANL < +12V 0.9 3.3 V Differential Input Hysteresis CANH Input Wake-Up Voltage Threshold VDIFF(HYST) VCANH (SHDN) RXD High-Level Output Voltage VOH RXD Low-Level Output Voltage VOL CANH and CANL Input Resistance Differential Input Resistance 150 SHDN = GND, VTXD = VCC (MAX3050) I = -100A 6 mV 9 0.8 VCC V V I = 10mA 0.8 I = 5mA 0.4 V RI 5 25 k RDIFF 10 100 k 0.3 VCC V MODE SELECTION (RS) Input Voltage for High Speed VSLP Input Voltage for Standby VSTBY 0.75 VCC Slope-Control Mode Voltage VSLOPE RRS = 24k to 180k 0.4 VCC Slope-Control Mode Current ISLOPE RRS = 24k to 180k Standby Mode ISTBY High-Speed Mode Current IHS V 0.6 VCC V -200 -10 A -10 +10 A -500 A 900 k VRS = 0 SHUTDOWN SHDN Input Pullup Resistor SHDN Input Voltage High SHDN Input Voltage Low RINSHDN MAX3057 500 2 V 0.5 V _______________________________________________________________________________________ 3 MAX3050/MAX3057 DC ELECTRICAL CHARACTERISTICS (continued) MAX3050/MAX3057 80V Fault-Protected, 2Mbps, Low Supply Current CAN Transceivers TIMING CHARACTERISTICS (VCC = +5V 10%, RL = 60, CL = 100pF, TA = TMIN to TMAX. Typical values are at VCC = +5V and TA = +25C.) (Figures 1, 2, and 3) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS TIMING VRS = 0 (2Mbps) Minimum Bit Time tBIT 2 RRS = 100k (125kbps) 8 RRS = 180k (62.5kbps) 25 Delay TXD to Bus Active tONTXD VRS = 0 Delay TXD to Bus Inactive tOFFTXD Delay TXD to Receiver Active Delay TXD to Receiver Inactive tONRXD tOFFRXD 0.5 RRS = 24k (500kbps) 40 ns VRS = 0 75 ns VRS = 0 (2Mbps) 120 ns RRS = 24k (500kbps) 0.4 RRS = 100k (125kbps) 1.6 RRS = 180k (62.5kbps) 5.0 VRS = 0 (2Mbps) 130 RRS = 24k (500kbps) 0.45 RRS = 100k (125kbps) 1.6 RRS = 180k (62.5kbps) 5.0 RRS = 24k (500kbps) Differential Output Slew Rate SR Bus Dominant to RXD Low s s ns s 14 RRS = 100k (125kbps) 7 RRS = 180k (62.5kbps) 1.6 V/s Standby mode 10 s 10 s 47 ms Time to Wake Up: CANH > 9V tWAKE SHDN = GND, VTXD = VCC (MAX3050) Time to Sleep Mode when Bus Is Recessive tSHDN CSHDN = 100nF (MAX3050) 10 Note 1: As defined by ISO, bus value is one of two complementary logical values: dominant or recessive. The dominant value represents the logical 1 and the recessive represents the logical 0. During the simultaneous transmission of the dominant and recessive bits, the resulting bus value is dominant. For MAX3050 and MAX3057 values, see the truth table in the Transmitter and Receiver sections. 4 _______________________________________________________________________________________ 80V Fault-Protected, 2Mbps, Low Supply Current CAN Transceivers MAX3050/MAX3057 120 VCC 0.1F VCC CAN CONTROLLER CANH 100pF TX0 MAX3050 MAX3057 CANL TXD RX0 RXD (100nF) SHDN 30pF RS GND GND 120 24k TO 180k ( ) ARE FOR MAX3050 ONLY. Figure 1. AC Test Circuit TXD 9V CANH CANH CANL DOMINANT VSHDN = 2V 0.9V CANH - CANL 0.5V RECESSIVE VCC/2 RXD VSHDN VCC/2 tONTXD tOFFTXD tONRXD tOFFRXD Figure 2. Timing Diagram for Dynamic Characteristics tWAKE Figure 3. Time to Wake Up (tWAKE) (MAX3050) _______________________________________________________________________________________ 5 Typical Operating Characteristics (VCC = 5V, RL = 60, CL = 100pF, TA = +25C, unless otherwise specified.) MAX3057 SLEW RATE vs. RRS MAX3050 AutoShutdown vs. CSHDN SLEEP TIME (ms) 15 TA = +25C 10 TA = -+125C 5 40 48 86 124 162 200 MAX3050 toc03 29 TA = -40C 25 100 0 200 300 0 400 400 800 1200 1600 CSHDN (nF) DATA RATE (kbps) RECEIVER PROPAGATION DELAY vs. TEMPERATURE, RRS = GND DRIVER PROPAGATION DELAY vs. TEMPERATURE, RRS = GND RECEIVER OUTPUT LOW vs. OUTPUT CURRENT 45 35 DOMINANT 25 DOMINANT 20 -15 20 55 90 800 TA = +25C 400 TA = -40C 15 15 TA = +125C 1200 25 MAX3050 toc06 MAX3050 toc05 30 RECESSIVE 2000 1600 VOLTAGE RXD (mV) RECESSIVE 35 DRIVER PROPAGATION DELAY (ns) MAX3050 toc04 55 0 -40 125 -7 26 59 92 125 0 5 10 15 20 25 TEMPERATURE (C) TEMPERATURE (C) OUTPUT CURRENT (mA) RECEIVER OUTPUT HIGH vs. OUTPUT CURRENT DIFFERENTIAL VOLTAGE vs. DIFFERENTIAL LOAD RL SUPPLY CURRENT vs. TEMPERATURE IN STANDBY MODE TA = +125C 1800 1200 TA = +25C 600 TA = +125C 2 TA = +25C 0 15 OUTPUT CURRENT (mA) 20 150 125 100 75 0 10 175 1 TA = -40C 5 MAX3050 toc09 TA = -40C 3 SUPPLY CURRENT (A) DIFFERENTIAL VOLTAGE (V) 2400 200 MAX3050 toc08 4 MAX3050 toc07 3000 0 TA = +25C TA = +125C RRS (k) 65 -50 31 27 0 10 RECEIVER PROPAGATION DELAY (ns) 60 20 0 6 33 SUPPLY CURRENT (mA) 80 TA = -40C SUPPLY CURRENT vs. DATA RATE 35 MAX3050 toc02 20 SLEW RATE (V/s) 100 MAX3050 toc01 25 VOLTAGE (VCC - RXD) (mV) MAX3050/MAX3057 80V Fault-Protected, 2Mbps, Low Supply Current CAN Transceivers 25 50 0 50 100 150 200 DIFFERENTIAL LOAD RL () 250 300 -50 -15 20 55 TEMPERATURE (C) _______________________________________________________________________________________ 90 125 80V Fault-Protected, 2Mbps, Low Supply Current CAN Transceivers LOOPBACK PROPAGATION DELAY vs. RRS MAX3050 toc10 LOOPBACK PROPAGATION DELAY (ns) RECEIVER PROPAGATION DELAY MAX3050 toc11 1400 1200 CANH - CANL 1000 800 600 RXD 2V/div 400 200 0 0 50 100 150 200 40ns/div RRS (k) DRIVER PROPAGATION DELAY DRIVER PROPAGATION DELAY MAX3050 toc12 MAX3050 toc13 TXD 5V/div TXD 2V/div RRS = 24k RRS = 100k RRS = 180k CANH - CANL RRS = GND 40ns/div 1s/div Pin Description PIN NAME FUNCTION 1 TXD Transmit Data Input. TXD is a CMOS/TTL-compatible input from a CAN controller. 2 GND Ground 3 VCC Supply Voltage. Bypass VCC to GND with a 0.1F capacitor. 4 RXD Receive Data Output. RXD is a CMOS/TTL-compatible output from the physical bus lines CANH and CANL. SHDN Shutdown Input. Drive SHDN low to put into shutdown mode (MAX3057). Place a capacitor from SHDN to ground to utilize the AutoShutdown feature of MAX3050. See the Shutdown and AutoShutdown sections for a full explanation of SHDN behavior. 6 CANL CAN Bus Line Low. CANL is fault protected to 80V. 7 CANH CAN Bus Line High. CANH is fault protected to 80V. 8 RS 5 Mode Select Pin. Drive RS low or connect to GND for high-speed operation. Connect a resistor from RS to GND to control output slope. Drive RS high to put into standby mode. See the Mode Selection section. _______________________________________________________________________________________ 7 MAX3050/MAX3057 Typical Operating Characteristics (continued) (VCC = 5V, RL = 60, CL = 100pF, TA = +25C, unless otherwise specified.) MAX3050/MAX3057 80V Fault-Protected, 2Mbps, Low Supply Current CAN Transceivers The transceivers are designed to operate from a single +5V supply and draw 56mA of supply current in dominant state and 3.6mA in recessive state. In standby mode, supply current is reduced to 125A. In shutdown mode, supply current is 15A. CANH and CANL are output short-circuit current limited and are protected against excessive power dissipation by thermal-shutdown circuitry that places the driver outputs into a high-impedance state. Detailed Description The MAX3050/MAX3057 interface between the protocol controller and the physical wires of the bus lines in a CAN. They are primarily intended for automotive applications requiring data rates up to 2Mbps and feature 80V fault protection against shorts in high-voltage systems. This fault protection allows the devices to withstand up to 80V with respect to ground with no damage to the device. The built-in fault tolerance allows the device to survive in industrial and automotive environments with no external protection devices. The devices provide differential transmit capability to the bus and differential receive capability to the CAN controller (Figure 4). The device has four modes of operation: high speed, slope control, standby, and shutdown. In high-speed mode, slew rates are not limited, making 2Mbps transmission speeds possible. Slew rates are controlled in slopecontrol mode, minimizing EMI and allowing use of unshielded twisted or parallel cable. In standby mode, receivers are active and transmitters are in high impedance. In shutdown mode, transmitters and receivers are turned off. Fault Protection The MAX3050/MAX3057 feature 80V fault protection. This extended voltage range of CANH and CANL bus lines allows use in high-voltage systems and communication with high-voltage buses. If data is transmitting at 2Mbps, the fault protection is reduced to 70V. Transmitter The transmitter converts a single-ended input (TXD) from the CAN controller to differential outputs for the bus lines (CANH, CANL). The truth table for the transmitter and receiver is given in Table 1. VCC MAX3050 THERMAL SHUTDOWN CANH TRANSMITTER CONTROL TXD RS CANL MODE SELECTION GND RXD RECEIVER 0.75V WAKE 7.5V AutoShutdown SHDN Figure 4. Functional Diagram 8 _______________________________________________________________________________________ 80V Fault-Protected, 2Mbps, Low Supply Current CAN Transceivers TXD RS SHDN CANH CANL BUS STATE RXD 0 VRS < 0.75 VCC V S HDN > 1.5V High Low Dominant* 0 1 or float VRS < 0.75 VCC V S HDN > 1.5V Recessive* 1 X VRS > 0.75 VCC X Floating Floating Floating 1 X X V S H D N < 0.5V Floating Floating Floating 1 5k to 25k to VCC/2 5k to 25k to VCC/2 X = Don't care. *As defined by ISO, bus value is one of two complementary logical values: dominant or recessive. The dominant value represents the logical 0 and the recessive represents the logical 1. During the simultaneous transmission of the dominant and recessive bits, the resulting bus value is dominant. High Speed Connect RS to ground to set the MAX3050/MAX3057 to high-speed mode. When operating in high-speed mode, the MAX3050/MAX3057 can achieve transmission rates of up to 2Mbps. Line drivers are switched on and off as quickly as possible. However, in this mode, no measures are taken to limit the rise and fall slope of the data signal, allowing for potential EMI emissions. If using the MAX3050/MAX3057 in high-speed mode, use shielded twisted-pair cable to avoid EMI problems. Slope Control Connect a resistor from RS to ground to select slopecontrol mode (Table 2). In slope-control mode, the gates of the line drivers are charged with a controlled current, proportional to the resistor connected to the RS pin. Transmission speed ranges from 40kbps to 500kbps. Controlling the rise and fall slope reduces EMI and allows the use of an unshielded twisted pair or a parallel pair of wires as bus lines. The transfer function for selecting the resistor value is given by: present at the RXD pin. If negative (i.e., V < 0.7V), a logic high is present. The receiver always echoes the transmitted data. The CANH and CANL common-mode range is -7V to +12V. RXD is logic high when CANH and CANL are shorted or terminated and undriven. If the differential receiver input voltage (CANH - CANL) is less than or equal to 0.5V, RXD is logic high. If (CANH - CANL) is greater than or equal to 0.9V, RXD is logic low. Standby If a logic high level is applied to RS, the MAX3050/ MAX3057 enter a low-current standby mode. In this mode, the transmitter is switched off and the receiver is switched to a low-current state. If dominant bits are detected, RXD switches to a low level. The microcontroller should react to this condition by switching the transceiver back to normal operation (through RS). Due to the reduced power mode, the receiver is slower in standby mode, and the first message may be lost at higher bit rates. Thermal Shutdown RRS (k) = 12000/speed (in kbps) See the Slew Rate vs. R RS graph in the Typical Operating Characteristics section. If the junction temperature exceeds +160C, the device is switched off. The hysteresis is approximately 20C, disabling thermal shutdown once the temperature reaches +140C. Receiver Shutdown (MAX3057) The receiver reads differential input from the bus lines (CANH, CANL) and transfers this data as a singleended output (RXD) to the CAN controller. It consists of a comparator that senses the difference V = (CANH CANL) with respect to an internal threshold of 0.7V. If this difference is positive (i.e., V > 0.7V), a logic low is Drive SHDN low to enter shutdown mode. In shutdown mode, the device is switched off. The outputs are high impedance to 80V. The MAX3057 features a pullup at SHDN. If shutdown is forced low and then left floating, the device switches back to normal operating mode. Table 2. Mode Selection Truth Table CONDITION FORCED AT PIN RS MODE RESULTING CURRENT AT RS VRS < 0.3 VCC High speed |IRs| < 500A 0.4 VCC< VRS < 0.6 VCC Slope control 10A < |IRs| < 200A VRS > 0.75 VCC Standby |IRs| < 10A _______________________________________________________________________________________ 9 MAX3050/MAX3057 Table 1. Transmitter and Receiver Truth Table MAX3050/MAX3057 80V Fault-Protected, 2Mbps, Low Supply Current CAN Transceivers AutoShutdown (MAX3050) To manage power consumption, AutoShutdown puts the device into shutdown mode after the device has been inactive for a period of time. The value of an external capacitor (C SHDN) connected to SHDN determines the threshold of inactivity time, after which the AutoShutdown triggers. Floating SHDN allows the MAX3050 to automatically change from active mode to shutdown. Use a 100nF capacitor as C SHDN for a typical threshold of 20ms. Change the capacitor value according to the following equation to change the threshold time period. CSHDN(nF) = 0.02 x time(s) (VCC - VSHDN ) CANH - CANL 1V/div FFT 500mV/div Figure 5. FFT Dominant Bus at 2Mbps V SHDN is the threshold of SHDN guaranteed to be less than 2V in the Electrical Characteristics table. Drive SHDN high to turn the MAX3050 on and disable AutoShutdown. CANH - CANL 1V/div When the MAX3050 is in shutdown mode, only the wake-up comparator is active, and normal bus communication is ignored. The remote master of the CAN system wakes up the MAX3050 with a signal greater than 9V on CANH. Internal circuitry in the MAX3050 puts the device in normal operation by driving SHDN high. FFT 200mV/div The MAX3057 does not have the AutoShutdown feature. Driver Output Protection The MAX3050/MAX3057 have several features that protect them from damage. Thermal shutdown switches off the device and puts CANH and CANL into high impedance if the junction temperature exceeds +160C. Thermal protection is needed particularly when a bus line is short circuited. The hysteresis for the thermal shutdown is approximately 20C. Additionally, a current-limiting circuit protects the transmitter output stage against short-circuits to positive and negative battery voltage. Although the power dissipation increases during this fault condition, this feature prevents destruction of the transmitter output stage. Figure 6. FFT Recessive Bus at 2Mbps CANH - CANL 1V/div FFT 500mV/div Figure 7. FFT Dominant Bus at 500kbps 10 ______________________________________________________________________________________ 80V Fault-Protected, 2Mbps, Low Supply Current CAN Transceivers CANH - CANL 1V/div FFT 200mV/div FFT 200mV/div Figure 8. FFT Recessive Bus at 500kbps Figure 10. FFT Recessive Bus at 62.5kbps Applications Information CANH - CANL 1V/div Reduced EMI and Reflections In slope-control mode, the CANH and CANL outputs are slew-rate limited, minimizing EMI and reducing reflections caused by improperly terminated cables. In general, a transmitter's rise time relates directly to the length of an unterminated stub, which can be driven with only minor waveform reflections. The following equation expresses this relationship conservatively: FFT 500mV/div Length = tRISE / (15ns/ft) Figure 9. FFT Dominant Bus at 62.5kbps where tRISE is the transmitter's rise time. The MAX3050 and MAX3057 require no special layout considerations beyond common practices. Bypass VCC to GND with a 0.1F ceramic capacitor mounted close to the IC with short lead lengths and wide trace widths. Chip Information TRANSISTOR COUNT: 1214 PROCESS: BiCMOS ______________________________________________________________________________________ 11 MAX3050/MAX3057 CANH - CANL 1V/div Package Information (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.) DIM A A1 B C e E H L N E H INCHES MILLIMETERS MAX MIN 0.069 0.053 0.010 0.004 0.014 0.019 0.007 0.010 0.050 BSC 0.150 0.157 0.228 0.244 0.016 0.050 MAX MIN 1.35 1.75 0.10 0.25 0.35 0.49 0.19 0.25 1.27 BSC 3.80 4.00 5.80 6.20 0.40 SOICN .EPS MAX3050/MAX3057 80V Fault-Protected, 2Mbps, Low Supply Current CAN Transceivers 1.27 VARIATIONS: 1 INCHES TOP VIEW DIM D D D MIN 0.189 0.337 0.386 MAX 0.197 0.344 0.394 MILLIMETERS MIN 4.80 8.55 9.80 MAX 5.00 8.75 10.00 N MS012 8 AA 14 AB 16 AC D C A B e 0 -8 A1 L FRONT VIEW SIDE VIEW PROPRIETARY INFORMATION TITLE: PACKAGE OUTLINE, .150" SOIC APPROVAL DOCUMENT CONTROL NO. 21-0041 REV. B 1 1 Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. 12 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 2002 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.