View MIC5247_31904.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

MIC5247
Micrel
MIC5247
150mA Low-Voltage Cap Linear Regulator Preliminary Information
General Description
The MIC5247 is an efficient, precise low voltage CMOS voltage regulator optimized for ultra-low-noise applications. The MIC5247 offers better than 1% initial accuracy, and 85A constant ground current over load (typically 85A). The MIC5247 provides a very low noise output, ideal for RF applications where quiet voltage sources are required. A noise bypass pin is also available for further reduction of output noise. Designed specifically for hand-held and battery-powered devices, the MIC5247 provides a logic compatible enable pin. When disabled, power consumption drops nearly to zero. The MIC5247 also works with low-ESR ceramic capacitors, reducing the amount of board space necessary for power applications, critical in hand-held wireless devices. Key features include current limit, thermal shutdown, a pushpull output for faster transient response, and an active clamp to speed up device turnoff. Available in the IttyBittyTM SOT-23-5 package, the MIC5247 also offers a range of fixed output voltages.
Features
* * * * * * * * * * * * * * * * * * * Ultralow noise Low voltage outputs Load independent, ultralow ground current: 85A 150mA output current Current limiting Thermal Shutdown Tight load and line regulation "Zero" off-mode current Stability with low-ESR capacitors Fast transient response Logic-controlled enable input Cellular phones and pagers Cellular accessories Battery-powered equipment Laptop, notebook, and palmtop computers PCMCIA VCC and VPP regulation/switching Consumer/personal electronics SMPS post-regulator/dc-to-dc modules High-efficiency linear power supplies
Applications
Ordering Information
Part Number MIC5247-1.5BM5 MIC5247-1.8BM5 MIC5247-2.0BM5 MIC5247-2.4BM5 Marking LU15 LU18 LU20 LU24 Voltage 1.5V 1.8V 2.0V 2.4V Junction Temp. Range -40C to +125C -40C to +125C -40C to +125C -40C to +125C Package SOT-23-5 SOT-23-5 SOT-23-5 SOT-23-5
Other voltages available. Contact Micrel for details.
Typical Application
VIN MIC5247-x.xBM5
1 2 Enable Shutdown 3 4 5
VOUT COUT
EN
EN (pin 3) may be connected directly to IN (pin 1).
CBYP (optional)
Ultra-Low-Noise Regulator Application
IttyBitty is a trademark of Micrel, Inc. Micrel, Inc. * 1849 Fortune Drive * San Jose, CA 95131 * USA * tel + 1 (408) 944-0800 * fax + 1 (408) 944-0970 * http://www.micrel.com
November 6, 2000
1
MIC5247
MIC5247
Micrel
Pin Configuration
EN GND IN
3 2 1
LUxx
4 5
BYP
OUT
MIC5247-x.xBM5
Pin Description
Pin Number 1 2 3 4 5 Pin Name IN GND EN BYP OUT Pin Function Supply Input Ground Enable/Shutdown (Input): CMOS compatible input. Logic high = enable; logic low = shutdown. Do not leave open. Reference Bypass: Connect external 0.01pF capacitor to GND to reduce output noise. May be left open. Regulator Output
Absolute Maximum Ratings (Note 1)
Supply Input Voltage (VIN) .................................. 0V to +7V Enable Input Voltage (VEN) .................................. 0V to VIN Junction Temperature (TJ) ...................................... +150C Storage Temperature ............................... -65C to +150C Lead Temperature (soldering, 5 sec.) ....................... 260C ESD, Note 3
Operating Ratings (Note 2)
Input Voltage (VIN) ......................................... +2.7V to +6V Enable Input Voltage (VEN) .................................. 0V to VIN Junction Temperature (TJ) ....................... -40C to +125C Thermal Resistance (JA)...................................... 235C/W
MIC5247
2
November 6, 2000
MIC5247
Micrel
Electrical Characteristics
VIN = VOUT + 1.0V; VIN = VEN; IOUT = 100A; TJ = 25C, bold values indicate -40C TJ +125C; unless noted. Symbol VO VLNR VLDR VIN - VOUT IQ IGND PSRR ILIM en Enable Input VIL VIH IEN Enable Input Logic-Low Voltage Enable Input Logic-High Voltage Enable Input Current VIN = 2.7V to 5.5V, regulator shutdown VIN = 2.7V to 5.5V, regulator enabled VIL 0.4V VIH 1.6V Shutdown Resistance Discharge Thermal Protection Thermal Shutdown Temperature Thermal Shutdown Hysteresis
Note 1. Note 2. Note 3. Note 4. Note 5. Exceeding the absolute maximum rating may damage the device. The device is not guaranteed to function outside its operating rating. Devices are ESD sensitive. Handling precautions recommended. Regulation is measured at constant junction temperature using low duty cycle pulse testing. Parts are tested for load regulation in the load range from 0.1mA to 150mA. Changes in output voltage due to heating effects are covered by the thermal regulation specification. Dropout voltage is defined as the input to output differential at which the output voltage drops 2% below its nominal value measured a1V differential. For outputs below 2.7V, dropout voltage is the input-to-output voltage differential with the minimum input voltage 2.7V. Minimum input operating voltage is 2.7V. Ground pin current is the regulator quiescent current plus pass transistor base current. The total current drawn from the supply is the sum of the load current plus the ground pin current.
Parameter Output Voltage Accuracy Line Regulation Load Regulation Load Regulation for 1.5V only Dropout Voltage Quiescent Current Ground Pin Current, Note 6
Conditions IOUT = 0mA VIN = VOUT + 0.1V to 6V IOUT = 0.1mA to 150mA, Note 4 IOUT = 0.1mA to 150mA, VOUT = 1.5V IOUT = 150mA (see Note 5) VEN 0.4V (shutdown) IOUT = 0mA IOUT = 150mA f 1kHz VOUT = 0V COUT = 10F, CBYP = 0.01F, f = 10Hz to 100kHz
Min -1 -2 -0.3
Typical
Max 1 2 +0.3
Units % % %/V % % mV A A A dB mA Vrms
2 3 150 0.2 85 85 50 160 300 30
3 4
1 150 150
Power Supply Rejection Current Limit Output Voltage Noise
0.8 1.6 1 0.01 0.01 500
0.4
V V A A C C
150 10
Note 6.
November 6, 2000
3
MIC5247
MIC5247
Micrel
Typical Characteristics
Power Supply Rejection Ratio
90 80 CBYP = 1F 70
PSRR (dB) PSRR (dB)
Power Supply Rejection Ratio
70 1F
Power Supply Rejection Ratio
60 50
PSRR (dB)
C
BYP
= 0.01F
0.01F 1F
60 50 0.01F 40 30 CBYP = 0 IL = 50mA 20 V = 3.4V IN 10 VOUT = 2.4V COUT =10F Ceramic 0
1x101 1x102 1x103
60 C =0 BYP 50 40 30 20 10
1x101 1x102
40 30 CBYP = 0
IL = 100A VIN = 3.4V VOUT = 2.4V C = 10F Ceramic
OUT
1x104
1x105
1x106
1x101
1x102
1x103
1x104
1x105 1x102
1x103
1x104
1x105
FREQUENCY (Hz)
1x106
FREQUENCY (Hz)
FREQUENCY (Hz)
Power Supply Rejection Ratio
60 50 1F
PSRR (dB)
OUTPUT SPECTRAL NOISE DENSITY (V/rt Hz)
Noise Performance
75
GROUND CURRENT (A)
Ground Current vs. Output Current
0.01F
1x10-5 CBYP = 0 1x10-6
74 73 72 71 70
40 30 CBYP = 0
1x100
1x10-1
1x101
1x102
1x103
1x104
1x105
1x106
1x101
1x102
1x103
1x104
1x105
1x106
1x10-8
OUTPUT CURRENT (mA)
FREQUENCY (Hz)
FREQUENCY (Hz)
Ground Pin Current
100 GROUND CURRENT (A) GROUND CURRENT (A) 80 60 40 20 0 -40 ILOAD = 100A -10 20 50 80 110 140 TEMPERATURE (C) 100 80 60 40 20
Ground Pin Current
100 GROUND CURRENT (A) 80 60 40 20
Ground Pin Current
ILOAD = 150mA 0 -40 -10 20 50 80 110 140 TEMPERATURE (C)
ILOAD = 100A 0 0 1 2 3 INPUT VOLTAGE (V) 4
Ground Pin Current
100 GROUND CURRENT (A) 80 60 40 20 ILOAD = 150mA 0 0 1 2 3 INPUT VOLTAGE (V) 4 0 0 3
Dropout Characteristics
SHORT CIRCUIT CURRENT (mA) 500 400 300 200 100
Short Circuit Current vs. Temperature
VOLTAGE OUT (V)
ILOAD = 100A 2 ILOAD = 150mA
1
1 2 3 INPUT VOLTAGE (V)
4
VOUT = 0 0 -40 -10 20 50 80 110 140 TEMPERATURE (C)
MIC5247
4
November 6, 2000
1x103
1x10
20 IL = 150mA VIN = 3.4V 10 VOUT = 2.4V COUT = 10F Ceramic 0
1x10
-7
CBYP = 0.01F VIN = 2.8V VOUT = 1.8V COUT = 4.7F
V
IN
= VOUT + 1
1
ILOAD = 50mA
1x106
0
20 IL = 100mA VIN = 3.4V 10 V = 2.4V OUT COUT = 10F Ceramic 0
MIC5247
Micrel
Output Voltage vs. Temperature
2.5 OUTPUT VOLTAGE (V)
Turn-On Time vs. Bypass Capacitance
200 COUT = 10F ILOAD = 100mA
150
TIME (s) ILOAD = 100A 1x100 1x10-5 1x10-4 1x10-3 1x10-2 -10 20 50 80 110 140 TEMPERATURE (C) 1x10-1 1x101 2.3 -40
2.4
100
Rise Time
50 Prop Delay 0
BYPASS CAPACITOR (F)
November 6, 2000
5
MIC5247
MIC5247
Micrel
Functional Characteristics
Load Transient Response
OUTPUT VOLTAGE (100mV/div.) INPUT VOLTAGE (1V/div.)
Line Transient Response
4.4V 3.4V
COUT = 10F CBYP = 0 VIN = 3.4V VOUT = 2.4V
OUTPUT CURRENT (100mA/div.)
100mA OUTPUT VOLTAGE (50mV/div.)
COUT = 10F VOUT = 2.4V ILOAD = 100A
100A
TIME (100s/div.)
TIME (500s/div.)
MIC5247
6
November 6, 2000
MIC5247
Micrel
Block Diagrams
IN Reference Voltage Startup/ Shutdown Control Quickstart/ Noise Cancellation BYP
PULL UP
EN
Thermal Sensor Undervoltage Lockout
FAULT
Error Amplifier
Current Amplifier
PULL DOWN
OUT
ACTIVE SHUTDOWN
GND
November 6, 2000
7
MIC5247
MIC5247
Micrel
dissipation of the package, use the junction-to-ambient thermal resistance of the device and the following basic equation: TJ(max) - TA PD(max) = JA TJ(max) is the maximum junction temperature of the die, 125C, and TA is the ambient operating temperature. JA is layout dependent; Table 1 shows examples of junction-toambient thermal resistance for the MIC5247.
Package SOT-23-5 (M5) JA Recommended Minimum Footprint 235C/W JA 1" Square Copper Clad 185C/W JC 145C/W
Applications Information
Enable/Shutdown The MIC5247 comes with an active-high enable pin that allows the regulator to be disabled. Forcing the enable pin low disables the regulator and sends it into a "zero" off-modecurrent state. In this state, current consumed by the regulator goes nearly to zero. Forcing the enable pin high enables the output voltage. This part is CMOS and the enable pin cannot be left floating; a floating enable pin may cause an indeterminate state on the output. Input Capacitor An input capacitor is not required for stability. A 1F input capacitor is recommended when the bulk ac supply capacitance is more than 10 inches away from the device, or when the supply is a battery. Output Capacitor The MIC5247 requires an output capacitor for stability. The design requires 1F or greater on the output to maintain stability. The capacitor can be a low-ESR ceramic chip capacitor. The MIC5247 has been designed to work specifically with the low-cost, small chip capacitors. Tantalum capacitors can also be used for improved capacitance over temperature. The value of the capacitor can be increased without bound. Bypass Capacitor A capacitor can be placed from the noise bypass pin to ground to reduce output voltage noise. The capacitor bypasses the internal reference. A 0.01F capacitor is recommended for applications that require low-noise outputs. The bypass capacitor can be increased without bound, further reducing noise and improving PSRR. Turn-on time remains constant with respect to bypass capacitance. Refer to the Typical Characteristics section for a graph of turn-on time vs. bypass capacitor. Transient Response The MIC5247 implements a unique output stage to dramatically improve transient response recovery time. The output is a totem-pole configuration with a P-channel MOSFET pass device and an N-channel MOSFET clamp. The N-channel clamp is a significantly smaller device that prevents the output voltage from overshooting when a heavy load is removed. This feature helps to speed up the transient response by significantly decreasing transient response recovery time during the transition from heavy load (100mA) to light load (85A). Active Shutdown The MIC5247 also features an active shutdown clamp, which is an N-channel MOSFET that turns on when the device is disabled. This allows the output capacitor and load to discharge, de-energizing the load. Thermal Considerations The MIC5247 is designed to provide 150mA of continuous current in a very small package. Maximum power dissipation can be calculated based on the output current and the voltage drop across the part. To determine the maximum power MIC5247 8
Table 1. SOT-23-5 Thermal Resistance The actual power dissipation of the regulator circuit can be determined using the equation: PD = (VIN - VOUT) IOUT + VIN IGND Substituting PD(max) for PD and solving for the operating conditions that are critical to the application will give the maximum operating conditions for the regulator circuit. For example, when operating the MIC5247-2.4BM5 at room temperature with a minimum footprint layout, the maximum input voltage for a set output current can be determined as follows: 125C - 25C PD(max) = 235C/W PD(max) = 425mW The junction-to-ambient thermal resistance for the minimum footprint is 235C/W, from Table 1. The maximum power dissipation must not be exceeded for proper operation. Using the output voltage of 2.4V and an output current of 150mA, the maximum input voltage can be determined. Because this device is CMOS and the ground current is typically 100A over the load range, the power dissipation contributed by the ground current is < 1% and can be ignored for this calculation. 425mW = (VIN - 2.4V) 150mA 425mW = VIN *150mA - 360mW 785mW = VIN *150mA VIN(max) = 5.2V Therefore, a 2.4V application at 150mA of output current can accept a maximum input voltage of 5.2V in a SOT-23-5 package. For a full discussion of heat sinking and thermal effects on voltage regulators, refer to the Regulator Thermals section of Micrel's Designing with Low-Dropout Voltage Regulators handbook. Fixed Regulator Applications
VIN MIC5247-x.xBM5
1 2 3 4 5
VOUT 1F 0.01F
Figure 1. Ultra-Low-Noise Fixed Voltage Application
November 6, 2000
MIC5247
Figure 1 includes a 0.01F capacitor for low-noise operation and shows EN (pin 3) connected to IN (pin 1) for an application where enable/shutdown is not required. COUT = 1F minimum.
VIN MIC5247-x.xBM5 V OUT
1 2 Enable Shutdown 3 4 5
Micrel
1.0F
EN
Figure 2. Low-Noise Fixed Voltage Application Figure 2 is an example of a low-noise configuration where CBYP is not required. COUT = 1F minimum.
November 6, 2000
9
MIC5247
MIC5247
Micrel
Package Information
1.90 (0.075) REF 0.95 (0.037) REF
1.75 (0.069) 1.50 (0.059)
3.00 (0.118) 2.60 (0.102)
DIMENSIONS: MM (INCH) 3.02 (0.119) 2.80 (0.110) 1.30 (0.051) 0.90 (0.035) 10 0 0.15 (0.006) 0.00 (0.000) 0.20 (0.008) 0.09 (0.004)
0.50 (0.020) 0.35 (0.014)
0.60 (0.024) 0.10 (0.004)
SOT-23-5 (M)
MICREL INC. 1849 FORTUNE DRIVE SAN JOSE, CA 95131
TEL
USA
+ 1 (408) 944-0800
FAX
+ 1 (408) 944-0970
WEB
http://www.micrel.com
This information is believed to be accurate and reliable, however no responsibility is assumed by Micrel for its use nor for any infringement of patents or other rights of third parties resulting from its use. No license is granted by implication or otherwise under any patent or patent right of Micrel Inc. (c) 2000 Micrel Incorporated
MIC5247
10
November 6, 2000

▲Up To Search▲

Price & Availability of MIC5247

	To Download MIC5247 Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .