Part Number Hot Search : 
MV12V 1340A1 MC75451 0E7XXXF R12KE ZMM5230B VRE101CA ENA1300
Product Description
Full Text Search
 

To Download SI9182 Datasheet File

  If you can't view the Datasheet, Please click here to try to view without PDF Reader .  
 
 


  Datasheet File OCR Text:
 SI9182
Vishay Siliconix
Micropower 250-mA CMOS LDO Regulator With Error Flag/Power-On-Reset
FEATURES
Low 105-mV Dropout at 250-mA Load Guaranteed 250-mA Output Current 500-mA Peak Output Current Capability Uses Low ESR Ceramic Output Capacitor Fast Load and Line Transient Response Only 100-mV(rms) Noise With Noise Bypass Capacitor D 1-mA Maximum Shutdown Current D Built-in Short Circuit and Thermal Protection D Out-Of-Regulation Error Flag (Power Good or POR) D D D D D D D Fixed 1.215-V, 1.5-V, 1.8-V, 2.0-V, 2.5-V, 2.8-V, 2.85-V, 2.9-V, 3.0-V, 3.3-V, 5.0-V, or Adjustable Output Voltage Options D Other Output Voltages Available by Special Order
APPLICATIONS
D Cellular Phones D Laptop and Palm Computers D PDA, Digital Still Cameras
DESCRIPTION
The SI9182 is a 250-mA CMOS LDO (low dropout) voltage regulator. The device features ultra low ground current and dropout voltage to prolong battery life in portable electronics. The SI9182 offers line/load transient response and ripple rejection superior to that of bipolar or BiCMOS LDO regulators. The device is designed to maintain regulation while delivering 500-mA peak current. This is useful for systems that have high surge current upon turn-on. The SI9182 is designed to drive the lower cost ceramic, as well as tantalum, output capacitors. The device is guaranteed stable from maximum load current down to 0-mA load. In addition, an external noise bypass capacitor connected to the device's CNOISE pin will lower the LDO's output noise for low noise applications. The SI9182 also includes an out-of-regulation error flag. When the output voltage is 5% below its nominal output voltage, the error flag output goes low. If a capacitor is connected to the device's delay pin, the error flag output pin will generate a delayed power-on-reset signal. The SI9182 is available in both standard and lead (Pb)-free MSOP-8 packages and is specified to operate over the industrial temperature range of -40 _C to 85 _C.
TYPICAL APPLICATIONS CIRCUITS
1 2 3 VIN 2.2 mF GND 4 CNOISE DELAY GND VIN SD ERROR SENSE/ADJ VOUT 8 7 6 5 2.2 mF VOUT VIN 2.2 mF GND 1 2 3 4 CNOISE DELAY GND VIN SD ERROR SENSE/ADJ VOUT 8 7 6 5 VOUT 2.2 mF
SI9182 FIGURE 1. Fixed Output
SI9182 FIGURE 2. Adjustable Output
1 0.1 mF 2 0.1 mF 3 4
CNOISE DELAY GND VIN
SD ERROR
8 7 6 5 2.2 mF 1 MW
ON/OFF POR VOUT
SENSE/ADJ VOUT
VIN 2.2 mF GND
SI9182
FIGURE 3. Low Noise, Full Features Application
Document Number: 71150 S-41221--Rev. F, 28-Jun-04 www.vishay.com
1
SI9182
Vishay Siliconix
ABSOLUTE MAXIMUM RATINGS
Input Voltage, VIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.5 V SD Input Voltage, VSD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3 V to VIN Output Current, IOUT . . . . . . . . . . . . . . . . . . . . . . . . . . Short Circuit Protected Output Voltage, VOUT . . . . . . . . . . . . . . . . . . . . . . . . -0.3 V to VO(nom) + 0.3 V Maximum Junction Temperature, TJ(max) . . . . . . . . . . . . . . . . . . . . . . . 150_C Storage Temperature, TSTG . . . . . . . . . . . . . . . . . . . . . . . . . . -55_C to 150_C ESD (Human Body Model) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 kV Power Dissipation (Package)a 8-Pin MSOP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 666 mW Thermal Impedance (QJA) 8-Pin MSOPb . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150_C/W Notes a. Device mounted with all leads soldered or welded to PC board. b. Derate 6.6 mW/_C above TA = 25_C
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.
RECOMMENDED OPERATING RANGE
Input Voltage, VIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 V to 6 V Output Voltage, VOUT (Adjustable Version) . . . . . . . . . . . . . . . . . . 1.5 V to 5 V SD Input Voltage, VSD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 V to VIN CIN = 2.2 mF, COUT = 2.2 mF (ceramic, X5R or X7R type) , CNOISE = 0.1 mF (ceramic) COUT Range = 1 mF to 10 mF ("10%, x5R or x7R type) CIN w COUT Operating Ambient Temperature, TA . . . . . . . . . . . . . . . . . . . . -40_C to 85_C Operating Junction Temperature, TJ . . . . . . . . . . . . . . . . . . . -40_C to 125_C
SPECIFICATIONS
Test Conditions Unless Otherwise Specified Parameter
Output Voltage Range Output Voltage Accuracy (Fixed Versions) Feedback Voltage (ADJ Version) Line Regulation (Except 5-V Version) Line Regulation (5-V Version) Line Regulation (ADJ Version) VIN DVOUT 100 VOUT(nom) VOUT
Limits
-40 to 85_C
Symbol
VIN = VOUT(nom) + 1 V IOUT = 1 mA V, A CIN = 2.2 mF, COUT = 2.2 mF, VSD = 1.5 V
Tempa
Full Room Full Room Full
Minb
1.5 -1.5 -2.5 1.191 1.179 -0.18 -0.18 -0.18 -0.18
Typc
Maxb
5 1.5 2.5
Unit
V % VO( O(nom) ) V
Adjustable Version 1 mA v IOUT v 250 mA
VADJ From VIN = VOUT(nom) + 1 V to VOUT(nom) + 2 V From VIN = 5.5 V to 6 V VOUT = 1.5 V, From VIN = 2.5 V to 3.5 V VOUT = 5 V, From VIN = 5.5 V to 6 V IOUT = 10 mA
1.215
1.239 1.251 0.18 0.18 0.18 0.18
Full Full Full Full Room Room Room Full Room Room Full Room Room Full Room Full
%/V
5 85 105
20 180 275 400 mV
Dropout Voltaged (@VOUT w 2 V) VIN - VOUT Dropout Voltaged (@VOUT t 2 V, VIN w 2 V)
IOUT = 200 mA IOUT = 250 mA IOUT = 200 mA IOUT = 250 mA IOUT = 0 mA IOUT = 200 mA IOUT = 250 mA
170 210
250 300 450
150 1000 1500 1200 1900 Document Number: 71150 S-41221--Rev. F, 28-Jun-04 m mA
Ground Pin Current
IGND
www.vishay.com
2
SI9182
Vishay Siliconix
SPECIFICATIONS
Test Conditions Unless Otherwise Specified Parameter
Shutdown Supply Current ADJ Pin Current Peak Output Current Output Noise Voltage
Limits
-40 to 85_C
Symbol
IIN(off) IADJ IO(peak) eN
VIN = VOUT(nom) + 1 V IOUT = 1 mA V, A CIN = 2.2 mF, COUT = 2.2 mF, VSD = 1.5 V
Tempa
Room Room Room Room Room Room Room Room Room Room Room Room
Minb
Typc
0.1 5
Maxb
1 100
Unit
mA nA mA
VSD = 0 V ADJ = 1.2 V VOUT w 0.95 x VOUT(nom), tpw = 2 ms BW = 50 Hz to 100 kHz IOUT = 150 mA w/o CNOISE CNOISE = 0.1 mF f = 1 kHz f = 10 kHz f = 100 kHz
500 200 100 60 60 40 10 30 5 2
mV (rms)
Ripple Rejection pp j
DVOUT/DVIN
IOUT = 150 mA
dB
Dynamic Line Regulation Dynamic Load Regulation VOUT Turn On Time Turn-On-Time
DVO(line) DVO(load) tON
VIN : VOUT(nom) + 1 V to VOUT(nom) + 2 V tR/tF = 5 ms, IOUT = 250 mA IOUT : 1 mA to 150 mA, tR/tF = 2 ms VIN = 4.3 V VOUT = 3.3 V w/o CNOISE Cap CNOISE = 0.1 mF
mV ms mS
Thermal Shutdown
Thermal Shutdown Junction Temp Thermal Hysteresis Short Circuit Current tJ(s/d) tHYST ISC VOUT = 0 V Room Room Room 165 20 800 _C mA
Shutdown Input
SD Input Voltage VIH VIL IIH IIL VHYST High = Regulator ON (Rising) Low = Regulator OFF (Falling) VSD = 0 V, Regulator OFF VSD = 6 V, Regulator ON Full Full Room Room Full 0.01 1.0 100 1.5 VIN 0.4 V
SD Input Currente Shutdown Hysteresis
mA mV
Error Output
Output High Leakage Output Low Voltageg Power_Good Trip Thresholdf, h (Rising) Hysteresis f Delay Pin Current Source IOFF VOL VTH VHYST IDELAY ERROR = VOUT(nom) ISINK = 2 mA Full Full Full Room Room 1.2 0.93 x VOUT 0.95 x VOUT 2% x VOUT 2.2 3.0 mA 0.01 2 0.4 0.97 x VOUT V mA
Notes a. Room = 25_C, Full = -40 to 85_C. b. The algebraic convention whereby the most negative value is a minimum and the most positive a maximum. c. Typical values are for DESIGN AID ONLY, not guaranteed nor subject to production testing. Typical values for dropout voltage at VOUT w 2 V are measured at VOUT = 3.3 V, while typical values for dropout voltage at VOUT < 2 V are measured at VOUT = 1.8 V. d. Dropout voltage is defined as the input to output differential voltage at which the output voltage drops 2% below the output voltage measured with a 1-V differential, provided that VIN does not not drop below 2.0 V. e. The device's shutdown pin includes a typical 6-MW internal pull-down resistor connected to ground. f. VOUT is defined as the output voltage of the DUT at 1 mA. g. The Error Output (Low) function is guaranteed from VOUT = 2.0 V to VOUT = 5.0 V. h. The Power_Good trip threshold function is guaranteed from VOUT = 1.5 V to VOUT = 5.0 V and VIN w 2.0 V.
Document Number: 71150 S-41221--Rev. F, 28-Jun-04
www.vishay.com
3
SI9182
Vishay Siliconix
TIMING WAVEFORMS
VIN
tON VNOM 0.95 VNOM VOUT
ERROR tDELAY
FIGURE 4. Timing Diagram for Power-Up
PIN CONFIGURATION
MSOP-8
CNOISE DELAY GND VIN 1 2 3 4 Top View 8 7 6 5 SD ERROR SENSE or ADJ VOUT
PIN DESCRIPTION
Pin Number
1 2 3 4 5 6 7 8 www.vishay.com
Name
CNOISE DELAY GND VIN VOUT SENSE or ADJ ERROR SD
Function
Noise bypass pin. For low noise applications, a 0.01-mF or larger ceramic capacitor should be connected from this pin to ground. Capacitor connected from this pin to ground will allow a delayed power-on-reset signal at the ERROR (Pin 7) output. Refer to Figure 4. Ground pin. Local ground for CNOISE and COUT. Input supply pin. Bypass this pin with a 2.2-mF ceramic or tantalum capacitor to ground. Output voltage. Connect COUT between this pin and ground. For fixed output voltage versions, this pin should be connected to VOUT (Pin 5). For adjustable output voltage version, this voltage feedback pin sets the output voltage via an external resistor divider. This open drain output is an error flag output which goes low when VOUT drops 5% below its nominal voltage. This pin also provides a power-on-reset signal if a capacitor is connected to the DELAY pin. By applying less than 0.4 V to this pin, the device will be turned off. Connect this pin to VIN if unused. Document Number: 71150 S-41221--Rev. F, 28-Jun-04
4
SI9182
Vishay Siliconix
ORDERING INFORMATION
Standard Part Number
SI9182DH-12-T1 SI9182DH-15-T1 SI9182DH-18-T1 SI9182DH-20-T1 SI9182DH-25-T1 SI9182DH-28-T1 SI9182DH-285-T1 SI9182DH-29-T1 SI9182DH-30-T1 SI9182DH-33-T1 SI9182DH-50-T1 SI9182DH-AD-T1
Lead (Pb)-Free Part Number
SI9182DH-12-T1--E3 SI9182DH-15-T1--E3 SI9182DH-18-T1--E3 SI9182DH-20-T1--E3 SI9182DH-25-T1--E3 SI9182DH-28-T1--E3 SI9182DH-285-T1--E3 SI9182DH-29-T1--E3 SI9182DH-30-T1--E3 SI9182DH-33-T1--E3 SI9182DH-50-T1--E3 SI9182DH-AD-T1--E3
Marking
8212 8215 8218 8220 8225 8228 822A 8229 8230 8233 8250 82AD
Voltage
1.215 V 1.5 V 1.8 V 2.0 V 2.5 V 2.8 V 2.85 V 2.9 V 3.0 V 3.3 V 5.0 V Adjustable
Temperature Range
Package
-40 to 85_C
MSOP-8
* Additional voltage options are available.
Eval Kit
SI9182DB
Temperature Range
-40 to 85_C
Board Type
Surface Mount
TYPICAL CHARACTERISTICS (INTERNALLY REGULATED, 25_C UNLESS NOTED)
Dropout Voltage vs. Load Current
250 VOUT = 3.3 V 200 2.5 V DROP (mV) V OUT (V) 150 2.0 1.5 1.0 50 0.5 0 0 100 200 300 ILOAD (mA) 400 500 0.0 0 1 2 3 VIN (V) 4 5 6 3.5 3.0 RLOAD = 16.5 W
Dropout Characteristic
100
Dropout Voltage vs. Temperature
180 150 120 V DROP (mV) 90 60 30 0 -50 IOUT = 10 mA IOUT = 0 mA -25 0 25 50 75 100 Junction Temperature (_C) 125 150 Dropout Voltage (mV) VOUT = 3.3 V IOUT = 250 mA IOUT = 200 mA 225 200 175 150 125 100 75 50 25 0 1.0
Dropout Voltage vs. VOUT
IOUT = 250 mA
IOUT = 200 mA
IOUT = 10 mA 1.5 2.0 2.5 3.0 VOUT 3.5 4.0 4.5 5.0
Document Number: 71150 S-41221--Rev. F, 28-Jun-04
www.vishay.com
5
SI9182
Vishay Siliconix
TYPICAL CHARACTERISTICS (INTERNALLY REGULATED, 25_C UNLESS NOTED)
Normalized Output Voltage vs. Load Current
0.30 0.15 0.00 -0.15 -0.30 -0.45 -0.60 -0.75 0 50 100 150 200 250 300 Load Current (mA) V OUT (%) -0.0 -0.2 -0.4 -0.6 IOUT = 200 mA -0.8 -1.0 -1.2 -40 IOUT = 250 mA IOUT = 100 mA
Normalized VOUT vs. Temperature
IOUT = 0 mA
Output Voltage (%)
-20
0
20
40
60
80
100
120
140
Junction Temperature (_C)
GND Current vs. Load Current
0.0 VOUT = 5 V -0.3 250 200 I GND ( mA) I GND ( mA) -0.6 25_C -0.9 300
No Load GND Pin Current vs. Input Voltage
85_C 150 100 25_C -40_C
-1.2
50 0 0 50 100 150 200 250 0 1
-1.5 Load Current (mA)
2
3
4
5
6
7
Input Voltage (V)
0
Power Supply Rejection
CIN = 10 mF COUT = 2.2 mF ILOAD = 150 mA
1500
GND Pin Current vs. Temperature and Load
VOUT = 5 V IOUT = 250 mA
-20
1200 IOUT = 200 mA I GND ( mA) 900
Gain (dB)
-40
600
-60
300
IOUT = 0 mA
-80 10
100
1000
10000
100000
1000000
0 -40
-20
0
20
40
60
80
100
120
140
Frequency (Hz)
JunctionTemperature (_C) Document Number: 71150 S-41221--Rev. F, 28-Jun-04
www.vishay.com
6
SI9182
Vishay Siliconix
TYPICAL WAVEFORMS
Load Transient Response-1 Load Transient Response-2
VOUT 10 mV/div VOUT 10 mV/div ILOAD 100 mA/div ILOAD 100 mA/div
5.00 ms/div
VOUT = 3.3 V COUT = 2.2 mF ILOAD = 1 to 150 mA trise = 2 msec
5.00 ms/div
VOUT = 3.3 V COUT = 2.2 mF ILOAD = 150 to 1 mA tfall = 2 msec
Load Transient Response-3
Load Transient Response-4
VOUT 10 mV/div VOUT 10 mV/div ILOAD 100 mA/div ILOAD 100 mA/div
5.00 ms/div
VOUT = 3.3 V COUT = 1.0 mF ILOAD = 1 to 150 mA trise = 2 msec
5.00 ms/div
VOUT = 3.3 V COUT = 1.0 mF ILOAD = 150 to 1 mA tfall = 2 msec
LineTransient Response-1
VOUT 1 V/div VIN 2 V/div
LineTransient Respons-2
VOUT 10 mV/div
VOUT 10 mV/div
5.00 ms/div
VINSTEP = 4.3 to 5.3 V VOUT = 3.3 V COUT = 2.2 mF CIN = 10 mF ILOAD = 250 mA trise = 5 msec
5.00 ms/div
VINSTEP = 5.3 to 4.3 V VOUT = 3.3 V COUT = 2.2 mF CIN = 10 mF ILOAD = 250 mA tfall = 5 msec
Document Number: 71150 S-41221--Rev. F, 28-Jun-04
www.vishay.com
7
SI9182
Vishay Siliconix
TYPICAL WAVEFORMS
Turn-On Sequence Turn-Off Sequence
VIN CH-3 2 V/div VIN 2 V/div VOUT 2 V/div VOUT CH-1 2 V/div
Cdelay 2 V/div ERROR 2 V/div
Cdelay CH-4 2 V/div ERROR CH-2 2 V/div VIN = 4.2 V VOUT = 3.3 V Cdelay = 0.1 mF CNOISE = 0.1 mF ILOAD = 250 mA 5.00 ms/div VIN = 4.2 V VOUT = 3.3 V Cdelay = 0.1 mF CNOISE = 0.1 mF ILOAD = 250 mA
10.00 ms/div
Output Noise
10.0
Noise Spectrum
mV 500 mV/div
Hz
0.01 1 ms/div VIN = 4.2 V VOUT = 3.3 V IOUT = 150 mA CNOISE = 0.1 mF BW = 10 Hz to 1 MHz 100 Hz VIN = 4.1 V VOUT = 3.3 V/10 mA CNOISE = 0.1 mF 1 MHz
www.vishay.com
8
Document Number: 71150 S-41221--Rev. F, 28-Jun-04
SI9182
Vishay Siliconix
BLOCK DIAGRAMS
Switches shown for device in normal operating mode (SD = HIGH) 6 VIN CIN 2.2 mF 4 SENSE 1 CNOISE
SD ON OFF
8
RFB2 6 MW RFB1 +
+ - 60 mV + - 2 mA
To VIN
5 COUT 2.2 mF 2 CDELAY 0.1 mF 7 REXT
VOUT
ERROR
GND
3
1.215 V VREF
+ -
- +
FIGURE 5. 250-mA CMOS LDO Regulator (Fixed Output)
6 VIN CIN 2.2 mF 4
ADJ
1
CNOISE
R2 8 VADJ R1
SD ON OFF
+ - 6 MW 60 mV + + - 2 mA
To VIN
5 COUT 2.2 mF 2 CDELAY 0.1 mF 7 REXT
VOUT
ERROR
GND
3
1.215 V VREF
+ -
- +
FIGURE 6. 250-mA CMOS LDO Regulator (Adjustable Output)
Document Number: 71150 S-41221--Rev. F, 28-Jun-04
www.vishay.com
9
SI9182
Vishay Siliconix
DETAILED DESCRIPTION
The SI9182 is a low drop out, low quiescent current, and very linear regulator family with very fast transient response. It is primarily designed for battery powered applications where battery run time is at a premium. The low quiescent current allows extended standby time while low drop out voltage enables the system to fully utilize battery power before recharge. The SI9182 is a very fast regulator with bandwidth exceeding 50 kHz while maintaining low quiescent current at light load conditions. With this bandwidth, the SI9182 is the fastest LDO available today. The SI9182 is stable with any output capacitor type from 1 mF to 10.0 mF. However, X5R or X7R ceramic capacitors are recommended for best output noise and transient performance. VIN VIN is the input supply pin. The bypass capacitor for this pin is not critical as long as the input supply has low enough source impedance. For practical circuits, a 1.0-mF or larger ceramic capacitor is recommended. When the source impedance is not low enough and/or the source is several inches from the SI9182, then a larger input bypass capacitor is needed. It is required that the equivalent impedance (source impedance, wire, and trace impedance in parallel with input bypass capacitor impedance) must be smaller than the input impedance of the SI9182 for stable operation. When the source impedance, wire, and trace impedance are unknown, it is recommended that an input bypass capacitor be used of a value that is equal to or greater than the output capacitor. VOUT VOUT is the output voltage of the regulator. Connect a bypass capacitor from VOUT to ground. The output capacitor can be any value from 1.0 mF to 10.0 mF. A ceramic capacitor with X5R or X7R dielectric type is recommended for best output noise, line transient, and load transient performance. GND Ground is the common ground connection for VIN and VOUT. It is also the local ground connection for CNOISE, DELAY, SENSE or ADJ, and SD. SENSE or ADJ SENSE is used to sense the output voltage. Connect SENSE to VOUT for the fixed voltage version. For the adjustable output version, use a resistor divider R1 and R2, connect R1 from VOUT to ADJ and R2 from ADJ to ground. R2 should be in the 25-kW to 150-kW range for low power consumption, while maintaining adequate noise immunity.
www.vishay.com
The formula below calculates the value of R1, given the desired output voltage and the R2 value,
V OUT * VADJ R2 VADJ (1)
R1 +
VADJ is nominally 1.215 V.
SHUTDOWN (SD) SD controls the turning on and off of the SI9182. VOUT is guaranteed to be on when the SD pin voltage equals or is greater than 1.5 V. VOUT is guaranteed to be off when theSD pin voltage equals or is less than 0.4 V. During shutdown mode, the SI9182 will draw less than 2-mA current from the source. To automatically turn on VOUT whenever the input is applied, tie the SD pin to VIN. ERROR ERROR is an open drain output that goes low when VOUT is less than 5% of its normal value. As with any open drain output, an external pull up resistor is needed. When a capacitor is connected from DELAY to GROUND, the error signal transition from low to high is delayed (see Delay section). This delayed error signal can be used as the power-on reset signal for the application system. (Refer to Figure 4.) The ERROR pin is disconnected if not used. DELAY A capacitor from DELAY to GROUND sets the time delay for ERROR going from low to high state. The time delay can be calculated using the following formula:
Tdelay +
VADJ Cdelay Idelay
(2)
The DELAY pin should be an open circuit if not used. CNOISE For low noise application, connect a high frequency ceramic capacitor from CNOISE to ground. A 0.01-mF or a 0.1-mF X5R or X7R is recommended.
Document Number: 71150 S-41221--Rev. F, 28-Jun-04
10


▲Up To Search▲   

 
Price & Availability of SI9182

All Rights Reserved © IC-ON-LINE 2003 - 2022  

[Add Bookmark] [Contact Us] [Link exchange] [Privacy policy]
Mirror Sites :  [www.datasheet.hk]   [www.maxim4u.com]  [www.ic-on-line.cn] [www.ic-on-line.com] [www.ic-on-line.net] [www.alldatasheet.com.cn] [www.gdcy.com]  [www.gdcy.net]


 . . . . .
  We use cookies to deliver the best possible web experience and assist with our advertising efforts. By continuing to use this site, you consent to the use of cookies. For more information on cookies, please take a look at our Privacy Policy. X