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ISSUED DATE :2005/04/15 REVISED DATE :
G5ELM 2576
Simple Switcher 3A Step-Down Voltage Regulator
The G5ELM2576 series of regulators are monolithic integrated circuits that provide all active functions for a step-down (buck) switching regulator, capable of driving 3A load with excellent line and load regulation. These devices are available in fixed output voltage of 3.3v, 5v, 12v, 15v and an adjustable output version. Requiring a minimum number of external components, these regulators are simple to use and include internal frequency compensation and a fixed-frequency oscillator. The G5ELM2576 series offers a high-efficiency replacement for popular three-terminal linear regulators. It substantially reduces the size of the heat sink, and in some cases no heat sink is required. A standard series if inductors optimized for use with the G5ELM2576 are available from several different manufactures. This feature greatly simplifies the design of switch-mode power supplies. Other feature include a guaranteed D to tolerance on output voltage within 4% specified input voltages and output load condition, and D 10% on the oscillator frequency. External shutdown is included, featuring 50uA (typical) standby current. The output switch includes cycle-by-cycle current limiting, as well as thermal shutdown for full protection under fault condition.
Description
Features & 5.0V, 12V, 15V and adjustable output versions 3.3V,
Applications & Simple high-efficiency step-down (buck) regulator
& On-card switching regulators & Positive to negative converter (Buck-Boost)
& Adjustable version output voltage range , 1.23V to 37V D% max over line and load conditions & Guaranteed 3A output current &Wide input voltage range & Efficient pre-regulator for linear regulators &Requires only 4 external components & 52kHz fixed frequency oscillator & TTL shutdown capability, low power standby mode & High efficiency & Uses readily available standard inductors & Thermal shutdown and current limit protection
Package Dimensions
REF. A b c D E L4
Millimeter Min. Max. 4.40 4.80 0.76 1.00 0.36 0.50 8.60 9.00 9.80 10.4 14.7 15.3
REF. L5 c1 L e L1 O
Millimeter Min. Max. 6.20 6.60 1.25 1.45 13.25 14.25 1.70 REF. 2.60 2.89 3.71 3.96
Typical Application (Fixed Output Voltage Version)
G5ELM2576-5.0
G5ELM2576
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Block Diagram
3.3V, R2=17k 5.0V, R2=3.1k 12V, R2=8.84k 15V, R2=11.3k For Adjustable version, R1=open, R2=0
Absolute Maximum Ratings (Note1)
Parameter Maximum Supply Voltage ON/OFF pin input Voltage Output Voltage to ground (steady state) Power dissipation Storage Temperature Maximum junction temperature Minimum ESD rating (C=100pF, R=1.5k ) Lead temperature (soldering, 10seconds)
Ratings 45 -0.3 V +VIN -1 Internally Limited -65 ~ +150 +150 2k +260 Ratings -40 TJ +125 40
Unit V V V : : V : Unit : V
Operating Ratings
Temperature range Supply Voltage
Parameter
G5ELM2576-3.3 Electrical Characteristics
Specifications with standard type face are for TJ=25 : , and those with boldface type apply over full operating temperature range
Parameter Symbol Conditions System Parameters (Note3) Test Circuit Figure 2 VIN=12V, ILOAD=0.5A Output Voltage VOUT Circuit of Figure 2 6V VIN 40V, 0.5A ILOAD 3A Output Voltage VOUT Circuit of Figure 2 Efficiency VIN=12V, ILOAD=3A
Min 3.234 3.168/3.135
Typ 3.3 3.3 75
Max 3.366 3.432/3.465
Unit V V %
G5ELM2576-5.0 Electrical Characteristics
Specifications with standard type face are for TJ=25 : , and those with boldface type apply over full operating temperature range
Parameter Symbol Conditions System Parameters (Note3) Test Circuit Figure 2 VIN=12V, ILOAD=0.5A Output Voltage VOUT Circuit of Figure 2 8V VIN 40V, 0.5A ILOAD 3A Output Voltage VOUT Circuit of Figure 2 Efficiency VIN=12V, ILOAD=3A G5ELM2576
Min 4.9 4.80/4.75
Typ 5.0 5.0 77
Max 5.1 5.20/5.25
Unit V V %
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G5ELM2576-12 Electrical Characteristics
Specifications with standard type face are for TJ=25 : , and those with boldface type apply over full operating temperature range
Parameter Symbol Conditions Min System Parameters (Note3) Test Circuit Figure 2 VIN=25V, ILOAD=0.5A 11.76 Output Voltage VOUT Circuit of Figure 2 15V VIN 40V, 0.5A ILOAD 3A 11.52/11.40 Output Voltage VOUT Circuit of Figure 2 Efficiency VIN=15V, ILOAD=3A
Typ 12 12 88
Max 12.24 12.48/12.60
Unit V V %
G5ELM2576-15 Electrical Characteristics
Specifications with standard type face are for TJ=25 : , and those with boldface type apply over full operating temperature range
Parameter Symbol Conditions Min System Parameters (Note3) Test Circuit Figure 2 VIN=25V, ILOAD=0.5A Output Voltage VOUT 14.70 Circuit of Figure 2 18V VIN 40V, 0.5A ILOAD 3A 14.40/14.25 Output Voltage VOUT Circuit of Figure 2 Efficiency VIN=18V, ILOAD=3A
Typ 15 15 88
Max 15.30 15.60/15.75
Unit V V %
G5ELM2576 Electrical Characteristics
Specifications with standard type face are for TJ=25 : , and those with boldface type apply over full operating temperature range
Parameter Symbol Conditions System Parameters (Note3) Test Circuit Figure 2 VIN=12V, ILOAD=0.5A, VOUT=5V Output Voltage VOUT Circuit of Figure 2 8V VIN 40V, 0.5A ILOAD 3A Output Voltage VOUT VOUT=5V, Circuit of Figure 2 Efficiency VIN=12V, ILOAD=3A, VOUT=5V
Min 1.217 1.193/1.180
Typ 1.230 1.230 77
Max 1.243 1.267/1.280
Unit V V %
All Output Voltage Version Electrical Characteristics
Specifications with standard type face are for TJ=25 : , and those with boldface type apply over full operating temperature range. Unless otherwise specified, VIN=12V for the 3.3V, 5.0V and Adjustable versions, VIN=25V for 12V version, and VIN=30V for 15V version. ILOAD=0.5A
Parameter Feedback bias current Oscillator frequency Saturation voltage Maximum duty cycle (ON) Current limit Output leakage current Quiescent current Standby quiescent current ON/OFF Control ON/OFF pin logic input level ON/OFF pin input current
Symbol
Ib
fO VSAT DC
Conditions VOUT=5V (adjustable version only) (Note 8) ILOAD=3A (Note 4) (Note 5) (Note 4, 8) (Note 6, 7) Output=0V Output=-1V (Note 6)
Min 47/42 93 4.2/3.5 2.2/2.4 -
Typ 50 52 1.4 98 5.8 7.5 5 50 1.4 1.2 12 0
Max 100/500 58/63 1.8/2.0
Unit nA kHz V %
ICL IL IQ
6.9/7.5 2 30 10 200 1.0/0.8 30 10
A mA mA uA
ISTBY ON/OFF pin=5V (OFF)
VIH VIL VOUT=0V VOUT=Nominal output voltage ON/OFF pin=5V (OFF) ON/OFF pin=0V (ON)
V uA
IIH IIL
G5ELM2576
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Note 1: Absolute Maximum Rating indicate limits beyond which damage to the device may occur. Operating Rating indicate conditions for which the device is intended to be functional, but do not guaranteed specific performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics. Note 2: All limits guaranteed at room temperature (standard type face) and at temperature extremes (bold type face). Note 3: External component such as the catch diode, inductor, input and output capacitors can affect switching regulator system performance. When the G5ELM2576 is used as shutdown in the Figure 2 test circuit, system performance will be as shown in system parameters section of Electrical Characteristics. Note 4: Output pin sourcing current. No diode, inductor or capacitor connected to output. Note 5: Feedback pin removed from output and connected to 0V. Note 6: Feedback pin removed from output and connected to +12V for the Adjustable, 3.3V and 5V versions, and +25V for the 12V and 15V versions, to force the output transistor OFF. Note 7: VIN=40V. Note 8: The oscillator frequency reduces to approximately 11 kHz in the event of an output short or an overload which causes the regulated output voltage to drop approximately 40% from the nominal output voltage. This self protection feature lowers the average power dissipation of the IC by lowering the minimum duty cycle from 5% down to approximately 2%.
Typical Performance Characteristics (circuit of Figure 2)
Normalized Output Voltage
Line Regulator
Dropout Voltage
G5ELM2576
Standby Quiescent Current
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Quiescent Current
Current Limit
Switch Saturation Voltage
Efficiency
Oscillator Frequency
Minimum Operating voltage
G5ELM2576
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Quiescent Current vs Duty Cycle
Feedback Voltage vs Duty Cycle
Minimum Power Dissipation
Feedback Pin Current
Output Voltage Change
Load Current
Switching Waveforms
VOUT=15V A: Output Pin Voltage, 50V/div B: Output Pin Current, 2A/div C: Inductor Current, 2A/div D: Output Ripple Voltage, 50mV/div AC Coupled Horizontal Time Base: 5us/div
Load Transient Response
G5ELM2576
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As in any switching regulator, layout is very important. Rapidly switching currents associated with wiring inductance generate voltage transients which can cause problems. For minimal inductance and ground loops, the length of the leads indicated by heavy lines should be kept as short as possible. Single-point grounding (as indicated) or ground plane construction should be used for best results. When using the Adjustable version, physically locate the programming resistors near the regulator, to keep the sensitive feedback wiring short.
Test Circuit and layout Guidelines
G5ELM2576
Cin-- 100uF, 75V, Aluminum Electrolytic Cout-- 1000uF, 25V Aluminum Electrolytic D1-- Schottky, MBR360 L1-- 100uH, Pulse Eng, PE92108 R1-- 2k, 0.1% R1-- 6.12k, 0.1%
G5ELM2576
Vout=VREF*(1+R2/R1) R2=R1*(Vout/VREF-1) Where VREF=1.23V, R1 between 1k and 5k
Figure 2
Important Notice: All rights are reserved. Reproduction in whole or in part is prohibited without the prior written approval of GTM. GTM reserves the right to make changes to its products without notice. GTM semiconductor products are not warranted to be suitable for use in life-support Applications, or systems. GTM assumes no liability for any consequence of customer product design, infringement of patents, or application assistance. Head Office And Factory: Taiwan: No. 17-1 Tatung Rd. Fu Kou Hsin-Chu Industrial Park, Hsin-Chu, Taiwan, R. O. C. TEL : 886-3-597-7061 FAX : 886-3-597-9220, 597-0785 China: (201203) No.255, Jang-Jiang Tsai-Lueng RD. , Pu-Dung-Hsin District, Shang-Hai City, China TEL : 86-21-5895-7671 ~ 4 FAX : 86-21-38950165
G5ELM2576
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