View REG101_999000.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

REG101
REG 101
www.ti.com
DMOS 100mA Low Dropout Regulator
FEATURES
q NEW DMOS TOPOLOGY: Ultra Low Dropout Voltage: 60mV typ at 100mA Output capacitor NOT required for stability q FAST TRANSIENT RESPONSE q VERY LOW NOISE: 23Vrms q HIGH ACCURACY: 1.5% max q HIGH EFFICIENCY: IGND = 500A at IOUT = 100mA Not Enabled: IGND = 10nA q 2.5V, 2.8V, 2.85V, 3.0V, 3.3V, 5.0V AND ADJUSTABLE OUTPUT VERSIONS q OTHER OUTPUT VOLTAGES AVAILABLE UPON REQUEST q FOLDBACK CURRENT LIMIT q THERMAL PROTECTION q SMALL SURFACE-MOUNT PACKAGES: SOT23-5 and SO-8
DESCRIPTION
The REG101 is a family of low noise, low dropout linear regulators with low ground pin current. Its new DMOS topology provides significant improvement over previous designs, including low dropout voltage (only 60mV typ at full load), and better transient performance. In addition, no output capacitor is required for stability, unlike conventional low dropout regulators that are difficult to compensate and require expensive low ESR capacitors greater than 1F. Typical ground pin current is only 500A (at IOUT = 100mA) and drops to 10nA when not enabled mode. Unlike regulators with PNP pass devices, quiescent current remains relatively constant over load variation and under dropout conditions. The REG101 has very low output noise (typically 23Vrms for VOUT = 3.3V with CNR = 0.01F), making it ideal for use in portable communications equipment. Accuracy is maintained over temperature, line, and load variations. Key parameters are guaranteed over the specified temperature range (-40C to +85C). The REG101 is well protected--internal circuitry provides a current limit which protects the load from damage. Thermal protection circuitry keeps the chip from being damaged by excessive temperature. The REG101 is available in the SOT23-5 and the SO-8 packages.
APPLICATIONS
q q q q q q PORTABLE COMMUNICATION DEVICES BATTERY-POWERED EQUIPMENT PERSONAL DIGITAL ASSISTANTS MODEMS BAR-CODE SCANNERS BACKUP POWER SUPPLIES
Enable VIN + 0.1F REG101 (Fixed Voltage Versions) Gnd + VOUT COUT(1) VIN
Enable VOUT + 0.1F REG101-A R1 Adj Gnd NOTE: (1) Optional. R2 + COUT(1)
NR NR = Noise Reduction
Copyright (c) 2000, Texas Instruments Incorporated
SBVS026A
Printed in U.S.A. December, 2000
SPECIFICATIONS
Boldface limits apply over the specified temperature range, TJ = -40C to +85C.
At TJ = +25C, VIN = VOUT + 1V (VOUT = 2.5V for REG101-A), VENABLE = 1.8V, IOUT = 2mA, CNR = 0.01F, and COUT = 0.1F(1), unless otherwise noted. REG101NA REG101UA PARAMETER OUTPUT VOLTAGE Output Voltage REG101-2.5 REG101-2.8 REG101-2.85 REG101-3.0 REG101-3.3 REG101-5 REG101-A Reference Voltage Adjust Pin Current Accuracy Over Temperature vs Temperature Includes Line and Load Over Temperature DC DROPOUT VOLTAGE(2) For all models Over Temperature VOLTAGE NOISE Without CNR With CNR (all fixed voltage models) OUTPUT CURRENT Current Limit(3) Over Temperature Short Circuit Current RIPPLE REJECTION f = 120Hz ENABLE CONTROL VENABLE High (output enabled) VENABLE Low (output disabled) IENABLE High (output enabled) IENABLE Low (output disabled) Output Disable Time Output Enable Time THERMAL SHUTDOWN Junction Temperature Shutdown Reset from Shutdown GROUND PIN CURRENT Ground Pin Current Enable Pin Low INPUT VOLTAGE Operating Input Voltage Range(4) Specified Input Voltage Range Over Temperature TEMPERATURE RANGE Specified Range Operating Range Storage Range Thermal Resistance SOT23-5 Surface Mount SO-8 Surface Mount VIN VIN > 1.8V VIN > 1.8V TJ TJ TA 1.8 VOUT + 0.4 VOUT + 0.6 -40 -55 -65 Junction-to-Ambient Junction-to-Ambient 200 150 10 10 10 +85 +125 +150 V V V C C C C/W C/W IGND IOUT = 2mA IOUT = 100mA VENABLE 0.5V VENABLE IENABLE VENABLE = 1.8V to VIN, VIN = 1.8V to 6.5 VENABLE = 0V to 0.5V COUT = 1.0F, RLOAD = 33 COUT = 1.0F, RLOAD = 33 VOUT 2.5 2.8 2.85 3.0 3.3 5 VREF VREF IADJ dVOUT/dT IOUT = 2mA to 100mA, VIN = (VOUT + 0.4V) to 10V VIN = (VOUT + 0.6V) to 10V VDROP IOUT = 2mA IOUT = 100mA IOUT = 100mA f = 10Hz to 100kHz CNR = 0, COUT = 0 CNR = 0.01F, COUT = 10F 130 110 1.267 0.2 0.5 50 0.8 4 60 5.5 1 1.5 V V V V V V V V A % % ppm/C % % mV mV mV Vrms Vrms 220 240 mA mA mA dB VIN 0.5 100 100 V V nA nA s ms CONDITION MIN TYP MAX UNITS
2.2 2.7
10 100 130
2.0
Vn
23Vrms/V * VOUT 7Vrms/V * VOUT 170 60
ICL ISC IOUT = 100mA
65 1.8 -0.2 1 2 200 1.5
160 140 400 500 0.01 500 650 0.2
C C A A A
JA JA
NOTES: (1) The REG101 does not require a minimum output capacitor for stability. However, transient response can be improved with proper capacitor selection. (2) Dropout voltage is defined as the input voltage minus the output voltage that produces a 2% change in the output voltage from the value at VIN = VOUT + 1V at fixed load. (3) Current limit is the output current that produces a 10% change in output voltage from VIN = VOUT + 1V and IOUT = 2mA. (4) The REG101 no longer regulates when VIN < VOUT + VDROP (MAX). In drop-out the impedance from VIN to VOUT is typically less than 1 at TJ = +25C.
2
REG101
SBVS026A
PIN CONFIGURATIONS
Top View
SO-8 VOUT(2) VOUT(2) NR/Adjust(1) GND 1 2 3 4 (U Package) 8 7 6 5 VIN(3) VIN(3) NC Enable VIN GND Enable 1 2 3
SOT23-5 5 VOUT
4 (N Package)
NR/Adjust(1)
NOTE: (1) For REG101A-A: voltage setting resistor pin. All other models: noise reduction capacitor pin. (2) Both pin 1 and pin 2 must be connected. (3) Both pin 7 and pin 8 must be connected.
ABSOLUTE MAXIMUM RATINGS(1)
Supply Input Voltage, VIN ....................................................... -0.3V to 12V Enable Input ............................................................................ -0.3V to VIN Output Short-Circuit Duration ...................................................... Indefinite Operating Temperature Range (TJ) ................................ -55C to +125C Storage Temperature Range (TA) ................................... -65C to +150C Lead Temperature (soldering, 3s, SOT23-5, and SO-8) ..................... +240C NOTE: (1) Stresses above these ratings may cause permanent damage. Exposure to absolute maximum conditions for extended periods may degrade device reliability.
ELECTROSTATIC DISCHARGE SENSITIVITY
This integrated circuit can be damaged by ESD. Burr-Brown recommends that all integrated circuits be handled with appropriate precautions. Failure to observe proper handling and installation procedures can cause damage. ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more susceptible to damage because very small parametric changes could cause the device not to meet its published specifications.
REG101
SBVS026A
3
PACKAGE/ORDERING INFORMATION
PACKAGE DRAWING NUMBER 331 PACKAGE MARKING R01B ORDERING NUMBER(1) REG101NA-5/250 REG101NA-5/2K5 REG101UA-5 REG101UA-5/2K5 REG101NA-3.3/250 REG101NA-3.3/2K5 REG101UA-3.3 REG101UA-3.3/2K5 REG101NA-3/250 REG101NA-3/2K5 REG101UA-3 REG101UA-3/2K5 REG101NA-2.85/250 REG101NA-2.85/2K5 REG101UA-2.85 REG101UA-2.85/2K5 REG101NA-2.8/250 REG101NA-2.8/2K5 REG101UA-2.8 REG101UA-2.8/2K5 REG101NA-2.5/250 REG101NA-2.5/2K5 REG101UA-2.5 REG101UA-2.5/2K5 REG101NA-A/250 REG101NA-A/2K5 REG101UA-A REG101UA-A/2K5 TRANSPORT MEDIA Tape and Reel Tape and Reel Rails Tape and Reel Tape and Reel Tape and Reel Rails Tape and Reel Tape and Reel Tape and Reel Rails Tape and Reel Tape and Reel Tape and Reel Rails Tape and Reel Tape and Reel Tape and Reel Rails Tape and Reel Tape and Reel Tape and Reel Rails Tape and Reel Tape and Reel Tape and Reel Rails Tape and Reel
PRODUCT 5V Output REG101NA-5
PACKAGE SOT23-5
"
REG101UA-5
"
SO-8
"
182
"
REG101U50
"
3.3V Output REG101NA-3.3
"
SOT23-5
"
331
"
R01C
"
REG101UA-3.3
"
SO-8
"
182
"
REG101U33
"
3V Output REG101NA-3
"
SOT23-5
"
331
"
R01D
"
REG101UA-3
"
SO-8
"
182
"
REG101U30
"
2.85V Output REG101NA-2.85
"
SOT23-5
"
331
"
R01N
"
REG101UA-2.85
"
SO-8
"
182
"
REG101285
"
2.8V Output REG101NA-2.8
"
SOT23-5
"
331
"
R01E
"
REG101UA-2.8
"
SO-8
"
182
"
REG101U28
"
2.5V Output REG101NA-2.5
"
SOT23-5
"
331
"
R01G
"
REG101UA-2.5
"
SO-8
"
182
"
REG101U25
"
Adjustable Output REG101NA-A
"
SOT23-5
"
331
"
R01A
"
REG101UA-A
"
SO-8
"
182
"
REG101UA
"
"
"
"
NOTE: (1) Models with a slash (/) are available only in Tape and Reel in the quantities indicated (e.g., /2K5 indicates 2500 devices per reel). Ordering 2500 pieces of "REG101UA-5/2K5" will get a single 2500-piece Tape and Reel.
Many custom output voltage versions, from 1.3V to 5.1V in 50mV increments, are available upon request. Minimum order quantities apply. Contact factory for details.
4
REG101
SBVS026A
TYPICAL PERFORMANCE CURVES
For all models, at TJ = +25C and VENABLE = 1.8V, unless otherwise noted.
OUTPUT VOLTAGE CHANGE vs IOUT (VIN = VOUT + 1V, Output Voltage % Change Refered to IOUT = 50mA at +25C) 0.80 0.60
Output Voltage Change (%) Output Voltage Change (%)
0.0%
LOAD REGULATION vs TEMPERATURE (VIN = VOUT + 1V)
0.40 0.20 0.00 -0.20 -0.40 -55C -0.60 -0.80 0 10 20 30 40 50 60 70 80 90 100 IOUT (mA) +25C +125C
-0.1%
10mA < IOUT < 100mA
-0.2%
-0.3% 2mA < IOUT < 1000mA -0.4% -50
-25
0
25
50
75
100
125
Temperature (C)
LINE REGULATION (Referred to VIN = VOUT + 1V at IOUT = 50mA) 20 0.10 0.08 15
LINE REGULATION vs TEMPERATURE IOUT = 100mA
Output Voltage Change (mV)
Output Voltage Change (%)
10 5 0 -5 -10 -15 -20 0 1
0.06 0.04 0.02 0.00 -0.02 -0.04 -0.06 -0.08 (VOUT + 0.4V) < VIN < 10V -25 0 25 50 75 100 125 (VOUT + 1V) < VIN < 10V
IOUT = 2mA IOUT = 50mA
IOUT = 100mA
2
3
4
5
6
7
8
-0.10 -50
VIN - VOUT (V)
Temperature (C)
DC DROPOUT VOLTAGE vs IOUT 100 100
DC DROPOUT VOLTAGE vs TEMPERATURE IOUT = 100mA
DC Dropout Voltage (mV)
DC Dropout Voltage (mV) 90 100
80
+125C
80
60 +25C 40 -55C 20
60
40
20
0 0 10 20 30 40 50 60 70 80 IOUT (mA)
0 -50
-25
0
25
50
75
100
125
Temperature (C)
REG101
SBVS026A
5
TYPICAL PERFORMANCE CURVES (Cont.)
For all models, at TJ = +25C and VENABLE = 1.8V, unless otherwise noted.
OUTPUT VOLTAGE ACCURACY HISTOGRAM 18 16
OUTPUT VOLTAGE DRIFT HISTOGRAM 30 25
Percentage of Units (%)
14 12 10 8 6 4 2 0
Percentage of Units (%) -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0
20 15 10 5 0 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 VOUT Drift (ppm/C) GROUND PIN CURRENT, NOT ENABLED vs TEMPERATURE
Error (%)
OUTPUT VOLTAGE vs TEMPERATURE (Output Voltage % Change Referred to IOUT = 50mA at +25C) 0.50 0.40 Output Voltage Change (%) 0.30 0.20 0.10 0.00 -0.10 -0.20 -0.30 -0.40 -0.50 -50 -25 0 25 50 IOUT = 100mA 0.0001 -50 IOUT = 50mA IOUT = 2mA 0.1000 1.0000
VENABLE = 0.5V VIN = VOUT + 1V
IGND (A)
0.0100
0.0010
75
100
125
-25
0
25
50
75
100
125
Temperature (C)
Temperature (C)
GROUND PIN CURRENT vs IOUT 600 VOUT = 5.0V 500 400
GROUND PIN CURRENT vs TEMPERATURE 600 VOUT = 5V 575 550 IOUT = 100mA
IGND (A)
VOUT = 3.3V 300 VOUT = 2.5V 200 100 VIN = VOUT + 1V 0 0 10 20 30 40 50 IOUT (mA) 60 70 80 90 100
IGND (A)
525 500 475 450 425 400 -50 VIN = VOUT + 1V -25 0 25 50
VOUT = 3.3V
VOUT = 2.5V
75
100
125
Temperature (C)
6
REG101
SBVS026A
TYPICAL PERFORMANCE CURVES (Cont.)
For all models, at TJ = +25C and VENABLE = 1.8V, unless otherwise noted.
RIPPLE REJECTION vs FREQUENCY 80 70
Ripple Rejection (dB)
RIPPLE REJECTION vs (VIN - VOUT) 30 REG101-3.3 25
Ripple Rejection (dB)
IOUT = 2mA IOUT = 2mA COUT = 10F IOUT = 100mA
60 50 40 30 20 10 0 10 100 1k
IOUT = 100mA COUT = 10F
20 15 10 5 0 Frequency = 100kHz COUT = 10F IOUT = 100mA 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
COUT = 0F
10k
100k
1M
10M
Frequency (Hz)
VIN - VOUT (V)
RMS NOISE VOLTAGE vs COUT 60 REG101-5.0 50
Noise Voltage (Vrms)
Noise Voltage (Vrms)
RMS NOISE VOLTAGE vs CNR 110 100 REG101-5.0 90 REG101-3.3 80 70 60 50 40 30 20 CNR = 0F 10Hz < BW < 100kHz 1 10 100 CNR (pF) 1k 10k REG101-2.5
40 REG101-3.3 30 20 REG101-2.5 10 0 CNR = 0.01F 10Hz < BW < 100kHz 0.1 1 COUT (F) 10
NOISE SPECTRAL DENSITY 10 IOUT = 100mA CNR = 0F 10 IOUT = 100mA CNR = 0.01F
NOISE SPECTRAL DENSITY
eN (V/Hz)
COUT = 1F
eN (V/Hz)
1
1
0.1
COUT = 0F COUT = 10F
COUT = 1F 0.1 COUT = 0F COUT = 10F 10 100 1k Frequency (Hz) 10k 100k
0.01 10 100 1k Frequency (Hz) 10k 100k
0.01
REG101
SBVS026A
7
TYPICAL PERFORMANCE CURVES (Cont.)
For all models, at TJ = +25C and VENABLE = 1.8V, unless otherwise noted.
FOLDBACK CURRENT LIMIT 3.5 3.0 REG101-3.3
Output Voltage (V) 180 160 140 IOUT (mA)
CURRENT LIMIT vs TEMPERATURE
ICL VIN = VOUT + 1V
2.5 2.0 1.5 1.0 ISC 0.5 0 0 20 40 60 80 100 120 140 160 180 Output Current (mA) ICL
120 100 80 ISC 60 40 -50
-25
0
25
50
75
100
125
Temperature (C)
LOAD TRANSIENT RESPONSE REG101-3.3 VIN = 4.3V
LINE TRANSIENT RESPONSE 50mV/div REG101-3.3 IOUT = 100mA VOUT
200mV/div
COUT = 0F
VOUT
COUT = 0
50mV/div
COUT = 10F VOUT
200mV/div
COUT = 10F VOUT
100mA 10mA 10s/div
IOUT
5.3V 4.3V 50s/div VIN
TURN-ON COUT = 0F RLOAD = 1600
1V/div
TURN-OFF COUT = 10F RLOAD = 33 COUT = 1.0F RLOAD = 33 COUT = 0F RLOAD = 1600 VOUT
COUT = 0F RLOAD = 33 COUT = 10F RLOAD = 33
VOUT
1V/div
REG101-3.3 VIN = VOUT + 1V CNR = 0.01F 250s/div
VENABLE
1V/div
1V/div
VENABLE REG101-3.3 CNR = 0.01F 200s/div
8
REG101
SBVS026A
BASIC OPERATION
The REG101 series of LDO (Low Drop-Out) linear regulators offers a wide selection of fixed output voltage versions and an adjustable output version. The REG101 belongs to a family of new generation LDO regulators that utilize a DMOS pass transistor to achieve ultra-low dropout performance and freedom from output capacitor constraints. Ground pin current remains under 650A over all line, load and temperature conditions. All versions have thermal and overcurrent protection, including fold-back current limit. The REG101 does not require an output capacitor for regulator stability and is stable over most output currents and with almost any value and type of output capacitor up to 10F or more. For applications where the regulator output current drops below several milliamps, stability can be enhanced by: adding a 1k to 2k load resistor; using capacitance values less than 10F; or keeping the effective series resistance greater than 0.05 including the capacitor's ESR and parasitic resistance in printed circuit board traces, solder joints, and sockets. Although an input capacitor is not required it is good analog design practice to connect a 0.1F low ESR capacitor across
the input supply voltage. This is recommended to improve ripple rejection by reducing input voltage ripple. Figure 1 shows the basic circuit connections for the fixed voltage models. Figure 2 gives the connections for the adjustable output version (REG101A) and example resistor values for some commonly used output voltages. Values for other voltages can be calculated from the equation shown in Figure 2. INTERNAL CURRENT LIMIT The REG101 internal current limit has a typical value of 170mA. A foldback feature limits the short-circuit current to a typical short-circuit value of 60mA. This helps to protect the regulator from damage under all load conditions. A curve of VOUT versus IOUT is given in Figure 3 and in the Typical Performance Curves section.
FOLDBACK CURRENT LIMIT 3.5 3.0 REG101-3.3
Output Voltage (V)
2.5 2.0 1.5 1.0 ICL 0.5 0 0 20 40 60 80 100 120 140 160 180 Output Current (mA) ICL
Enable VIN 0.1F In REG101 Gnd NR CNR 0.01F Out COUT VOUT
Optional
FIGURE 1. Fixed Voltage Nominal Circuit for REG101.
FIGURE 3. Foldback Current Limit of the REG101-3.3 at 25C.
Enable 3 5 VIN 0.1F 1 REG101 4 2 Gnd IADJ R1 Adj R2 3.0 3.3 Optional Pin numbers for SOT23 package. VOUT = (1 + R1/R2) * 1.267V To reduce current through divider, increase resistor values (see table at right). As the impedance of the resistor divider increases, IADJ (~200nA) may introduce an error. CFB improves noise and transient response. 5.0 CFB 0.01F COUT Load VOUT EXAMPLE RESISTOR VALUES VOUT (V) 1.267 2.5 R1 ()(1) Short 11.3k 1.13k 15.8k 1.58k 18.7k 1.87k 34.0k 3.40k R2 ()(1) Open 11.5k 1.15k 11.5k 1.15k 11.5k 1.15k 11.5k 1.15k
NOTE: (1) Resistors are standard 1% values.
FIGURE 2. Adjustable Voltage Circuit for REG101A.
REG101
SBVS026A
9
Noise Voltage (Vrms)
ENABLE The Enable pin is active HIGH and compatible with standard TTL-CMOS levels. Inputs below 0.5V (max) turn the regulator off and all circuitry is disabled. Under this condition ground pin current drops to approximately 10nA. When a pull-up resistor is used, and operation below 1.8V is required, use values < 50k. OUTPUT NOISE A precision band-gap reference is used for the internal reference voltage, VREF. This reference is the dominant noise source within the REG101 and it generates approximately 29Vrms in the 10Hz to 100kHz bandwidth at the reference output. The regulator control loop gains up the reference noise, so that the noise voltage of the regulator is approximately given by: V R + R2 VN = 29Vrms 1 = 29Vrms * OUT R2 VREF Since the value of VREF is 1.267V, this relationship reduces to: VN = 23 Vrms * VOUT V
RMS NOISE VOLTAGE vs CNR
110 100
REG101-5.0
90
REG101-3.3
80 70 60 50 40 30 20 1 10
REG101-2.5
CNR = 0F 10Hz < BW < 100kHz
100
CNR (pF)
1k
10k
FIGURE 5. Output Noise vs Noise Reduction Capacitor. Noise can be further reduced by carefully choosing an output capacitor, COUT. Best overall noise performance is achieved with very low (< 0.22F) or very high (> 2.2F) values of COUT. See "RMS Noise Voltage vs COUT" in the Typical Performance Curves section. The REG101 utilizes an internal charge pump to develop an internal supply voltage sufficient to drive the gate of the DMOS pass element above VIN. The charge-pump switching noise (nominal switching frequency = 2MHz) is not measurable at the output of the regulator.
Connecting a capacitor, CNR, from the Noise Reduction (NR) pin to ground, as shown in Figure 4, forms a low-pass filter for the voltage reference. For CNR= 10nF, the total noise in the 10Hz to 100kHz bandwidth is reduced by approximately a factor of 2.8 for VO = 3.3V. This noise reduction effect is shown in Figure 5 and as "RMS Noise Voltage vs CNR" in the Typical Performance Curves section.
VIN
NR (fixed output versions only) CNR (optional) VREF (1.26V)
Low Noise Charge Pump
DMOS Pass Transistor Over Current Over Temp Protection VOUT R1 Adj (Adjustable Versions)
Enable
R2 REG101
NOTE: R1 and R2 are internal on fixed output versions.
FIGURE 4. Block Diagram.
10
REG101
SBVS026A
DROP-OUT VOLTAGE The REG101 uses an N-channel DMOS as the "pass" element. When the input voltage is within a few tens of millivolts of the output voltage, the DMOS device behaves like a resistor. Therefore, for low values of VIN to VOUT, the regulator's input-to-output resistance is the RdsON of the DMOS pass element (typically 600m). For static (DC) loads, the REG101 will typically maintain regulation down to VIN to VOUT voltage drop of 60mV at full rated output current. In Figure 6, the bottom line (DC dropout) shows the minimum VIN to VOUT voltage drop required to prevent drop-out under DC load conditions. For large step changes in load current, the REG101 requires a larger voltage drop across it to avoid degraded transient response. The boundary of this "transient drop-out" region is shown as the top line in Figure 6. Values of VIN to VOUT voltage drop above this line insure normal transient response. In the transient dropout region between "DC" and "Transient", transient response recovery time increases. The time required to recover from a load transient is a function of both the magnitude and rate of the step change in load current and the available "headroom" VIN to VOUT voltage drop. Under worst-case conditions (full-scale load change with VIN to VOUT voltage drop close to DC dropout levels), the REG101 can take several hundred microseconds to re-enter the specified window of regulation.
TRANSIENT RESPONSE The REG101 response to transient line and load conditions improves at lower output voltages. The addition of a capacitor (nominal value 0.47F) from the output pin to ground may improve the transient response. In the adjustable version, the addition of a capacitor, CFB (nominal value 10nF), from the output to the adjust pin will also improve the transient response. THERMAL PROTECTION The REG101 has thermal shutdown circuitry that protects the regulator from damage. The thermal protection circuitry disables the output when the junction temperature reaches approximately 160C, allowing the device to cool. When the junction temperature cools to approximately 140C, the output circuitry is again enabled. Depending on various conditions, the thermal protection circuit may cycle on and off. This limits the dissipation of the regulator, but may have an undesirable effect on the load. Any tendency to activate the thermal protection circuit indicates excessive power dissipation or an inadequate heat sink. For reliable operation, junction temperature should be limited to 125C, maximum. To estimate the margin of safety in a complete design (including heat sink), increase the ambient temperature until the thermal protection is triggered. Use worst-case loads and signal conditions. For good reliability, thermal protection should trigger more than 35C above the maximum expected ambient condition of your application. This produces a worst-case junction temperature of 125C at the highest expected ambient temperature and worst-case load. The internal protection circuitry of the REG101 has been designed to protect against overload conditions. It was not intended to replace proper heat sinking. Continuously running the REG101 into thermal shutdown will degrade reliability.
140 120
Dropout Voltage (mV)
100 80 60 40
Full Scale IOUT Transient
DC 20 0 0 25 50 75 IOUT (mA) 100 125 150
FIGURE 6. Transient and DC Dropout.
REG101
SBVS026A
11
POWER DISSIPATION The REG101 is available in two different package configurations. The ability to remove heat from the die is different for each package type and, therefore, presents different considerations in the printed circuit-board layout. The PCB area around the device that is free of other components moves the heat from the device to the ambient air. While it is difficult-to-impossible to quantify all of the variables in a thermal design of this type, performance data for several configurations are shown in Figure 7. Power dissipation depends on input voltage, load condition and duty cycle. Power dissipation is equal to the product of the average output current times the voltage across the output element, VIN to VOUT voltage drop.
Power dissipation can be minimized by using the lowest possible input voltage necessary to assure the required output voltage. REGULATOR MOUNTING Solder pad footprint recommendations for the various REG101 devices are presented in Application Bulletin "Solder Pad Recommendations for Surface-Mount Devices" (AB-132), available from the Texas Instruments web site (www.ti.com).
PD = (VIN - VOUT ) * I OUT ( AVG )
1.2 CONDITIONS 1.0 0.8 PACKAGE 0.6 0.4 0.3 0 0 25 50 75 100 125 Ambient Temperature (C) SOT23-5 SO-8 SOT23-5 SO-8
Power Dissipation (Watts)
JA
200C/W 150C/W
FIGURE 7. Maximum Power Dissipation versus Ambient Temperature for the Various Packages.
12
REG101
SBVS026A
IMPORTANT NOTICE Texas Instruments and its subsidiaries (TI) reserve the right to make changes to their products or to discontinue any product or service without notice, and advise customers to obtain the latest version of relevant information to verify, before placing orders, that information being relied on is current and complete. All products are sold subject to the terms and conditions of sale supplied at the time of order acknowledgment, including those pertaining to warranty, patent infringement, and limitation of liability. TI warrants performance of its semiconductor products to the specifications applicable at the time of sale in accordance with TI's standard warranty. Testing and other quality control techniques are utilized to the extent TI deems necessary to support this warranty. Specific testing of all parameters of each device is not necessarily performed, except those mandated by government requirements. Customers are responsible for their applications using TI components. In order to minimize risks associated with the customer's applications, adequate design and operating safeguards must be provided by the customer to minimize inherent or procedural hazards. TI assumes no liability for applications assistance or customer product design. TI does not warrant or represent that any license, either express or implied, is granted under any patent right, copyright, mask work right, or other intellectual property right of TI covering or relating to any combination, machine, or process in which such semiconductor products or services might be or are used. TI's publication of information regarding any third party's products or services does not constitute TI's approval, warranty or endorsement thereof.
Copyright (c) 2000, Texas Instruments Incorporated

▲Up To Search▲

Price & Availability of REG101

	To Download REG101 Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .