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LTC3250-1.5/LTC3250-1.2 High Efficiency, Low Noise, Inductorless Step-Down DC/DC Converter
FEATURES
s s s s s s s s s s s s s
DESCRIPTIO
2.7V to 5.5V Input Voltage Range No Inductors Li-Ion (3.6V) to 1.5V with 81% Efficiency Low Noise Constant Frequency Operation Output Voltages: 1.5V 4%, 1.2V 4% Output Current: 250mA Shutdown Disconnects Load from VIN Low Operating Current: IQ = 35A Low Shutdown Current: ISD < 1A Oscillator Frequency = 1.5MHz Soft-Start Limits Inrush Current at Turn-On Short-Circuit and Overtemperature Protected Low Profile (1mm) SOT-23 Package
The LTC(R)3250-1.5/LTC3250-1.2 are charge pump stepdown DC/DC converters that produce a 1.5V or 1.2V regulated output from a 2.7V to 5.5V input. The parts use switched capacitor fractional conversion to achieve typical efficiency two times higher than that of a linear regulator. No inductors are required. A unique constant frequency architecture provides a low noise regulated output as well as lower input noise than conventional charge pump regulators.* High frequency operation (fOSC = 1.5MHz) simplifies filtering to further reduce conducted noise. The part also uses Burst Mode(R) operation to improve efficiency at light loads. Low operating current (35A with no load, <1A in shutdown) and low external parts count (three small ceramic capacitors) make the LTC3250-1.5/LTC3250-1.2 ideally suited for space constrained battery powered applications. The parts are short-circuit and overtemperature protected, and are available in a low profile (1mm) 6-pin ThinSOTTM package.
, LTC and LT are registered trademarks of Linear Technology Corporation Burst Mode is a registered trademark of Linear Technology Corporation ThinSOT is a trademark of Linear Technology Corporation. *U.S. Patent #6, 411, 531
APPLICATIO S
Handheld Computers Cellular Phones s Digital Cameras s Handheld Medical Instruments s Low Power DSP Supplies
s s
TYPICAL APPLICATIO
1F
Efficiency vs Input Voltage (IOUT = 100mA)
100 90 80 70
EFFICIENCY (%)
Li-Ion to 1.5V Output with Shutdown
60 50 40 30 20 10 LDO
VIN 3.2V TO 4.2V Li-Ion 1F
C- VIN
C+ VOUT 4.7F
VOUT = 1.5V 4% 100mA
LTC3250-1.5 OFF ON SHDN GND
3250 TA1a
0 3.0
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LTC3250-1.5 3.5 4.0 4.5 VIN (V) 5.0 5.5
3250 TA01b
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U
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LTC3250-1.5/LTC3250-1.2
ABSOLUTE
(Note 1)
AXI U RATI GS
PACKAGE/ORDER I FOR ATIO
ORDER PART NUMBER
TOP VIEW VIN 1 GND 2 SHDN 3 6 C+ 5 VOUT 4 C-
VIN to GND ................................................... -0.3V to 6V SHDN to GND ............................... -0.3V to (VIN + 0.3V) IOUT (Note 2)....................................................... 350mA Operating Ambient Temperature Range (Note 3) ........................................................... - 40C to 85C Storage Temperature Range ................ - 65C to 150C Lead Temperature (Soldering, 10 sec).................. 300C
LTC3250ES6-1.5 LTC3250ES6-1.2 S6 PART MARKING LTZE LTAGJ
S6 PACKAGE 6-LEAD PLASTIC SOT-23
TJMAX = 150C, JA = 230C/W, JC = 102C/W
Consult LTC Marketing for parts specified with wider operating temperature ranges.
The q denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. VIN = 3.6V, CFLY = 1F, CIN = 1F, COUT = 4.7F unless otherwise noted.
SYMBOL VIN VOUT PARAMETER LTC3250-1.5 Operating Voltage Range LTC3250-1.2 Operating Voltage Range LTC3250-1.5 Output Voltage Range IOUT 50mA 3.1V VIN 5.5V IOUT 100mA 3.2V VIN 5.5V IOUT 250mA 3.5V VIN 5V IOUT 150mA 2.7V < VIN < 5.5V IOUT 250mA 2.9V VIN 5V IOUT = 0mA SHDN = 0V CONDITIONS
q q q q q q q
ELECTRICAL CHARACTERISTICS
MIN 3.1 2.7 1.44 1.44 1.44 1.15 1.15
TYP
MAX 5.5 5.5
UNITS V V
V
1.5 1.5 1.5 1.2 1.2 35 0.01 12 4
1.56 1.56 1.56 1.25 1.25 60 1
LTC3250-1.2 Output Voltage Range IIN VRB VRC fOSC VIH VIL IIH IIL tON Operating Current Shutdown Current Burst Mode Operation Output Ripple Continuous Mode Output Ripple Switching Frequency SHDN Input Hi Voltage SHDN Input Low Voltage SHDN Input Current SHDN Input Current Turn On Time LTC3250-1.5 Load Regulation LTC3250-1.2 Load Regulation Line Regulation ROL Open-Loop Output Impedance
mVP-P mVP-P 1.8 0.4 1 1 MHz V V A A ms mV/mA mV/mA %/V
q q q
1.2 1.2 -1 -1
1.5 0.8 0.8
SHDN = VIN SHDN = 0V RLOAD = 6 0 IOUT 250mA 0 IOUT 250mA IOUT = 250mA IOUT = 250mA (Note 4)
q q
0.8 0.15 0.12 0.2 1.0
Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: Based on long term current density limitations. Note 3: The LTC3250-1.5E/LTC3250-1.2E are guaranteed to meet specified performance from 0C to 70C. Specifications over the -40C and 85C operating temperature range are assured by design characterization and correlation with statistical process controls.
Note 4: Output not in regulation; ROL = (VIN/2 - VOUT)/IOUT. Note 5: This IC includes overtemperature protection that is intended to protect the device during momentary overload conditions. Junction temperature will exceed 125C when overtemperature protection is active. Continuous operation above the specified maximum operating junction temperature may impair device reliability.
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V V
V
W
U
U
WW
W
V
A A
LTC3250-1.5/LTC3250-1.2 TYPICAL PERFOR A CE CHARACTERISTICS
No Load Supply Current vs Supply Voltage
50 45 TA = 85C 40
IIN (A)
FREQUENCY (MHz)
3.1V < VIN < 5.5V (LTC3250-1.5) 2.7V < VIN < 5.5V (LTC3250-1.2)
TA = 25C 35 TA = -40C 30 25 20 2.7
VSHDN (mV)
3.1
3.5
3.9 4.3 VIN (V)
4.7
(LTC3250-1.5) Output Voltage vs Load Current
1.60 1.58 1.56
EFFICIENCY (%)
VIN = 3.6V TA = 25C
1.54
VOUT (V)
1.50 1.48 1.46 1.44 1.42 1.40 0 50 100 150 200 IOUT (mA) 250 300
50 40 30 20 10 0 0.1 1 10 IOUT (mA)
VIN = 5V
VOUT (V)
1.52
(LTC3250-1.2) Output Voltage vs Load Current
1.30 1.28 1.26 VIN = 3.6V TA = 25C 100 90 80 70 VIN = 3V
EFFICIENCY (%)
1.24
VOUT (V)
VOUT (V)
1.22 1.20 1.18 1.16 1.14 1.12 1.10 0 50 100 150 200 IOUT (mA) 250 300
UW
5.1
Oscillator Frequency vs Supply Voltage
1.8 1.7 1.6 TA = 85C 1.5 TA = -40C 1.4 1.3 1.2 2.7 TA = 25C 3.1V < VIN < 5.5V (LTC3250-1.5) 2.7V < VIN < 5.5V (LTC3250-1.2)
1200 1100 1000 900 800 700 600 500
VSHDN Threshold Voltage vs Supply Voltage
3.1V < VIN < 5.5V (LTC3250-1.5) 2.7V < VIN < 5.5V (LTC3250-1.2)
TA = -40C TA = 25C TA = 85C
5.5
3.2
3.7
4.2 VIN (V)
4.7
5.2
3250 G02
400 2.7
3.2
3.7
4.2 VIN (V)
4.7
5.2
3250 G03
3250 G01
Efficiency vs Output Current
100 90 80 70 60 TA = 25C
1.60
Output Voltage vs Supply Voltage
1.58 1.56 1.54 1.52 1.50 1.48 1.46 1.44 1.42 IOUT = 0mA IOUT = 100mA IOUT = 250mA TA = 25C
VIN = 3.3V VIN = 3.6V VIN = 4V
100
1000
3250 G05
1.40 3.0
3.5
4.5 4.0 VIN (V)
5.0
5.5
3250 G06
3250 G04
Efficiency vs Output Current
TA = 25C
1.30
Output Voltage vs Supply Voltage
1.28 1.26 1.24 1.22 1.20 1.18 1.16 1.14 1.12 IOUT = 250mA TA = 25C
VIN = 2.7V
60 50 40 30 20 10 0 0.1 1 10 IOUT (mA)
VIN = 3.5V VIN = 4.5V
IOUT = 0mA IOUT = 100mA
100
1000
3250 G13
1.10 2.7
3.2
3.7
4.2 VIN (V)
4.7
5.2
3250 G14
3250 G12
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LTC3250-1.5/LTC3250-1.2 TYPICAL PERFOR A CE CHARACTERISTICS
Output Voltage Soft-Start and Shutdown (LTC3250-1.5)
HI SHDN LOW
IOUT 250mA 15mA
VOUT 500mV/DIV
RL = 6 VIN = 3.6V
Line Transient Response (LTC3250-1.5)
4.5V 3.5V
VIN 50mV/DIV AC
VIN
VOUT 20mV/DIV AC
IOUT = 200mA
4
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Output Current Transient Response (LTC3250-1.5)
VOUT 20mV/DIV AC
3250 G07
VIN = 3.6V
3250 G08
Input Voltage Ripple vs Input Capacitor (LTC3250-1.5)
CI = 1F
VIN 50mV/DIV AC
CI = 10F
3250 G09
IOUT = 250mA RSOURCE = 0.2
3250 G10
Output Voltage Ripple (LTC3250-1.5)
VOUT 20mV/DIV AC
COUT = 4.7F 1X5R16.3V IOUT = 250mA VIN = 3.6V
3250 G11
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LTC3250-1.5/LTC3250-1.2
PI FU CTIO S
VIN (Pin 1): Input Supply Voltage. Bypass VIN with a 1F low ESR ceramic capacitor. GND (Pin 2): Ground. Connect to a ground plane for best performance. SHDN (Pin 3): Active Low Shutdown Input. A low voltage on SHDN disables the LTC3250-1.5/LTC3250-1.2. SHDN must not be allowed to float. C - (Pin 4): Flying Capacitor Negative Terminal VOUT (Pin 5): Regulated Output Voltage. VOUT is disconnected from VIN during shutdown. Bypass VOUT with a 4.7F low ESR ceramic capacitor (2.5F min, ESR <100m). C + (Pin 6): Flying Capacitor Positive Terminal.
BLOCK DIAGRA
VREF
+
BURST DETECT CIRCUIT
-
W
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LTC3250-1.5/ LTC3250-1.2 THERMAL SHUTDOWN (>160C) SHDN 3 SWITCH CONTROL AND SOFT-START 1.5MHz OSCILLATOR
VIN
1
CHARGE PUMP 6 C+ 5 VOUT
4 C-
2 GND
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LTC3250-1.5/LTC3250-1.2
OPERATIO
The LTC3250-1.5/LTC3250-1.2 use a switched capacitor charge pump to step down VIN to a regulated 1.5V 4% or 1.2V 4% (respectively) output voltage. Regulation is achieved by sensing the output voltage through an internal resistor divider and modulating the charge pump output current based on the error signal. A 2-phase nonoverlapping clock activates the charge pump switches. On the first phase of the clock current is transferred from VIN, through the flying capacitor, to VOUT. Not only is current being delivered to VOUT on the first phase, but the flying capacitor is also being charged up. On the second phase of the clock the flying capacitor is connected from VOUT to ground, delivering the charge stored during the first phase of the clock to VOUT. Using this method of switching, only half of the output current is delivered from VIN, thus achieving twice the efficiency over a conventional LDO. The sequence of charging and dis-charging the flying capacitor continues at a free running frequency of 1.5MHz (typ). This constant frequency architecture provides a low noise regulated output as well as lower input noise than conventional switch-capacitor charge pump regulators. The part also has a low current Burst Mode operation to improve efficiency even at light loads. In shutdown mode all circuitry is turned off and the LTC3250-1.5/LTC3250-1.2 draw only leakage current from the VIN supply. Furthermore, VOUT is disconnected from VIN. The SHDN pin is a CMOS input with a threshold voltage of approximately 0.8V. The LTC3250-1.5/LTC32501.2 are in shutdown when a logic low is applied to the SHDN pin. Since the SHDN pin is a high impedance CMOS input it should never be allowed to float. To ensure that its state is defined it must always be driven with a valid logic level. Short-Circuit/Thermal Protection The LTC3250-1.5/LTC3250-1.2 have built-in short-circuit current limiting as well as overtemperature protection. During short-circuit conditions, the parts will automatically limit the output current to approximately 500mA. At higher temperatures, or if the input voltage is high enough to cause excessive self heating on chip, thermal shutdown circuitry will shut down the charge pump once the junction
6
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(Refer to Simplified Block Diagram)
temperature exceeds approximately 160C. It will reenable the charge pump once the junction temperature drops back to approximately 150C. The LTC3250-1.5/LTC32501.2 will cycle in and out of thermal shutdown without latchup or damage until the short-circuit on VOUT is removed. Long term overstress (IOUT > 350mA, and/or TJ > 140C) should be avoided as it can degrade the performance of the part. Soft-Start To prevent excessive current flow at VIN during start-up, the LTC3250-1.5/LTC3250-1.2 have a built-in soft-start circuitry. Soft-start is achieved by increasing the amount of current available to the output charge storage capacitor linearly over a period of approximately 500s. Soft-start is enabled whenever the device is brought out of shutdown, and is disabled shortly after regulation is achieved. Low Current "Burst Mode" Operation To improve efficiency at low output currents, Burst Mode operation was included in the design of the LTC3250-1.5/ LTC3250-1.2. An output current sense is used to detect when the required output current drops below an internally set threshold (30mA typ.). When this occurs, the part shuts down the internal oscillator and goes into a low current operating state. The LTC3250-1.5/LTC3250-1.2 will remain in the low current operating state until the output has dropped enough to require another burst of current. Unlike traditional charge pumps whose burst current is dependant on many factors (i.e. supply voltage, switch resistance, capacitor selection, etc.), the LTC32501.5/LTC3250-1.2's burst current is set by the burst threshold and hysteresis. This means that the VOUT ripple voltage in Burst Mode will be fixed and is typically 12mV for a 4.7F output capacitor. Power Efficiency The power efficiency () of the LTC3250-1.5/LTC32501.2 are approximately double that of a conventional linear regulator. This occurs because the input current for a 2 to 1 step-down charge pump is approximately half the output
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LTC3250-1.5/LTC3250-1.2
OPERATIO
current. For an ideal 2 to 1 step-down charge pump the power efficiency is given by:
POUT VOUT * IOUT 2VOUT = = PIN VIN 1 VIN * IOUT 2
The switching losses and quiescent current of the LTC3250-1.5/LTC3250-1.2 are designed to minimize efficiency loss over the entire output current range, causing only a couple % error from the theoritical efficiency. For example with VIN = 3.6V, IOUT = 100mA and VOUT regulating to 1.5V the measured efficiency is 80.6% which is in close agreement with the theoretical 83.3% calculation. VOUT Capacitor Selection The ESR and value of capacitors used with the LTC32501.5/LTC3250-1.2 determine several important parameters such as regulator control loop stability, output ripple, and charge pump strength. The value of COUT directly controls the amount of output ripple for a given load current. Increasing the size of COUT will reduce the output ripple. To reduce output noise and ripple, it is suggested that a low ESR (<0.1) ceramic capacitor (4.7F or greater) be used for COUT. Tantalum and aluminum capacitors are not recommended because of their high ESR. Both ESR and value of the COUT can significantly affect the stability of the LTC3250-1.5/LTC3250-1.2. As shown in the block diagram, the LTC3250-1.5/LTC3250-1.2 use a control loop to adjust the strength of the charge pump to match the current required at the output. The error signal of this loop is stored directly on the output charge storage capacitor. Thus the charge storage capacitor also serves to form the dominant pole for the control loop. To prevent ringing or instability it is important for the output capacitor to maintain at least 2.5F of capacitance over all conditions (see "Ceramic Capacitor Selection Guidelines" section). Likewise excessive ESR on the output capacitor will tend to degrade the loop stability of the LTC3250-1.5/LTC32501.2. The closed-loop output resistance is designed to be
U
(Refer to Simplified Block Diagram)
0.15 for the LTC3250-1.5 and 0.12 for the LTC3250-1.2. For a 250mA load current change the output voltage will change by about 37mV for the LTC3250-1.5 and by 30mV for the LTC 3250-1.2. If the ESR of the output capacitor is greater than the closed-loop-output impedance the part will cease to roll-off in a simple one-pole fashion and poor load transient response or instability could result. Ceramic capacitors typically have exceptional ESR performance and combined with a tight board layout should yield excellent stability and load transient performance. Further output noise reduction can be achieved by filtering the LTC3250-1.5/LTC3250-1.2 output through a very small series inductor as shown in Figure 1. A 10nH inductor will
10nH (TRACE INDUCTANCE) VOUT LTC3250-1.5/ LTC3250-1.2 GND
3250 F01
VOUT 4.7F 0.22F
Figure 1. 10nH Inductor Used for Additional Output Noise Reduction
reject the fast output transients, thereby presenting a nearly constant output voltage. For economy the 10nH inductor can be fabricated on the PC board with about 1cm (0.4") of PC board trace. VIN Capacitor Selection The constant frequency architecture used by the LTC3250-1.5/LTC3250-1.2 makes input noise filtering much less demanding than conventional charge pump regulators. On a cycle by cycle basis, the LTC3250-1.5/ LTC3250-1.2 input current will go from IOUT/2 to 0mA. Lower ESR will reduce the voltage steps caused by changing input current, while the absolute capacitor value will determine the level of ripple. For optimal input noise and ripple reduction, it is recommended that a low ESR 1F or greater ceramic capacitor be used for CIN (see "Ceramic Capacitor Selection Guidelines" section). Aluminum and tantalum capacitors are not recommended because of their high ESR.
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LTC3250-1.5/LTC3250-1.2
OPERATIO
Flying Capacitor Selection
Warning: A polarized capacitor such as tantalum or aluminum should never be used for the flying capacitor since its voltage can reverse upon start-up of the LTC3250-1.5/LTC3250-1.2. Ceramic capacitors should always be used for the flying capacitor.
The flying capacitor controls the strength of the charge pump. In order to achieve the rated output current it is necessary for the flying capacitor to have at least 0.4F of capacitance over operating temperature with a 2V bias (see "Ceramic Capacitor Selection Guidelines" section). If only 100mA or less of output current is required for the application the flying capacitor minimum can be reduced to 0.15F. Ceramic Capacitor Selection Guidelines Capacitors of different materials lose their capacitance with higher temperature and voltage at different rates. For example, a ceramic capacitor made of X7R material will retain most of its capacitance from -40C to 85C whereas a Z5U or Y5V style capacitor will lose considerable capacitance over that range (60% to 80% loss typ.). Z5U and Y5V capacitors may also have a very strong voltage coefficient causing them to lose an additional 60% or more of their capacitance when the rated voltage is applied. Therefore, when comparing different capacitors it is often more appropriate to compare the amount of achievable capacitance for a given case size rather than discussing the specified capacitance value. For example, over rated voltage and temperature conditions, a 4.7F, 10V, Y5V ceramic capacitor in a 0805 case may not provide any more capacitance than a 1F, 10V, X7R available in the same 0805 case. In fact over bias and temperature range, the 1F, 10V, X7R will provide more capacitance than the 4.7F, 10V, Y5V. The capacitor manufacturer's data sheet should be consulted to determine what value of capacitor is needed to ensure minimum capacitance values are met over operating temperature and bias voltage.
8
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(Refer to Simplified Block Diagram)
Below is a list of ceramic capacitor manufacturers and how to contact them:
AVX Kemet Murata Taiyo Yuden Vishay 1-(803)-448-1943 1-(864)-963-6300 1-(800)-831-9172 1-(800)-348-2496 1-(800)-487-9437 www.avxcorp.com www.kemet.com www.murata.com www.t-yuden.com www.vishay.com
Layout Considerations Due to the high switching frequency and transient currents produced by the LTC3250-1.5/LTC3250-1.2 careful board layout is necessary for optimal performance. A true ground plane and short connections to all capacitors will improve performance and ensure proper regulation under all conditions. Figure 2 shows the recommended layout configuration.
1F
VIN 1F GND SHDN 4.7F
VOUT
3250 F02
LTC3250-1.5/LTC3250-1.2 VIA TO GROUND PLANE
Figure 2. Recommended Layout
The flying capacitor pins, C + and C - will have very high edge rate wave forms. The large dv/dt on these pins can couple energy capacitively to adjacent printed circuit board runs. Magnetic fields can also be generated if the flying capacitors are not close to the LTC3250-1.5/LTC3250-1.2 (i.e. the loop area is large). To decouple capacitive energy transfer, a Faraday shield may be used. This is a grounded PC trace between the sensitive node and the LTC3250-1.5/ LTC3250-1.2 pins. For a high quality AC ground it should be returned to a solid ground plane that extends all the way to the LTC3250-1.5/LTC3250-1.2.
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LTC3250-1.5/LTC3250-1.2
OPERATIO
Thermal Management For higher input voltages and maximum output current there can be substantial power dissipation in the LTC3250-1.5/LTC3250-1.2. If the junction temperature increases above approximately 160C the thermal shutdown circuitry will automatically deactivate the output. To reduce the maximum junction temperature, a good thermal connection to the PC board is recommended. Connecting the GND pin (Pin 2) to a ground plane, and maintaining a solid ground plane under the device can reduce the thermal resistance of the package and PC board considerably. Derating Power at Higher Temperatures To prevent an overtemperature condition in high power applications Figure 3 should be used to determine the maximum combination of ambient temperature and power
POWER DISSIPATION (W)
U
(Refer to Simplified Block Diagram)
dissipation. The power dissipated in the LTC3250-1.5/ LTC3250-1.2 should always fall under the line shown (i.e. within the safe region) for a given ambient temperature. The power dissipated in the LTC3250-1.5/LTC3250-1.2 is given by the expression:
V PD = IN - VOUT IOUT 2
This derating curve assumes a maximum thermal resistance, JA , of 175C/W for the 6-pin ThinSOT-23. This thermal resistances can be achieved from a printed circuit board layout with a solid ground plane (2000mm2)on at least one layer with a good thermal connection to the ground pin of the LTC3250-1.5/LTC3250-1.2. Operation outside of this curve will cause the junction temperature to exceed 140C which may trigger the thermal shutdown circuitry and ultimately reduce the life of the device.
1.2 1.0 0.8 0.6 0.4 0.2 0 -50
JA = 175C/W TJ = 140C
0 25 50 75 -25 AMBIENT TEMPERATURE (C)
100
3250 * F03
Figure 3. Maximum Power Dissipation vs Ambient Temperature
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LTC3250-1.5/LTC3250-1.2
TYPICAL APPLICATIO S
Efficiency vs Output Current Fixed 3.3V Input to 1.5V Output with Shutdown
1F
EFFICIENCY (%)
4 VIN = 3.3V 1F 1 C- VIN
6 C+ 5 VOUT VOUT = 1.5V 4% 4.7F 2
3250 TA02a
LTC3250-1.5 OFF ON 3 SHDN GND
Li-Ion or 3-Cell NiMH to 1.5V Output with Shutdown
1F
4 1 1-CELL Li-Ion OR 3-CELL NiMH 1F 3 C- VIN
EFFICIENCY (%)
LTC3250-1.5 SHDN GND 2
OFF ON
3-Cell NiMH to 1.2V Output with Shutdown
1F
4 VIN = 2.7V TO 5V 3-CELL NiMH 1F 3 1 C- VIN
EFFICIENCY (%)
LTC3250-1.2 SHDN GND 2
OFF ON
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100 90 80 70 60 50 40 30 20 10
TA = 25C
VIN = 3.3V
0 0.1
1
10 IOUT (mA)
100
1000
3250 TA02b
Efficiency vs Output Current
100 90 80 TA = 25C VIN = 3.6V VIN = 4V VIN = 5V
6 C+ 5 VOUT
70 VOUT = 1.5V 4% 4.7F 60 50 40 30 20
3250 TA03a
10 0 0.1 1 10 IOUT (mA) 100 1000
3250 TA03b
Efficiency vs Input Voltage (IOUT = 100mA)
100 90 80 TA = 25C
6 C+ 5 VOUT
70 VOUT = 1.2V 4% 4.7F 60 50 40 30 20
3250 TA05a
LTC3250
LDO
10 0 2.7 3.2 3.7 4.2 VIN (V) 4.7 5.2
3250 TA05b
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LTC3250-1.5/LTC3250-1.2
PACKAGE DESCRIPTIO U
S6 Package 6-Lead Plastic TSOT-23
(Reference LTC DWG # 05-08-1636)
2.90 BSC (NOTE 4) 1.22 REF 1.4 MIN 2.80 BSC 1.50 - 1.75 (NOTE 4) PIN ONE ID 0.95 BSC 0.30 - 0.45 6 PLCS (NOTE 3) 0.80 - 0.90 0.20 BSC 1.00 MAX DATUM `A' 0.01 - 0.10 0.09 - 0.20 (NOTE 3) 1.90 BSC
S6 TSOT-23 0302
0.62 MAX
0.95 REF
3.85 MAX 2.62 REF
RECOMMENDED SOLDER PAD LAYOUT PER IPC CALCULATOR
0.30 - 0.50 REF NOTE: 1. DIMENSIONS ARE IN MILLIMETERS 2. DRAWING NOT TO SCALE 3. DIMENSIONS ARE INCLUSIVE OF PLATING 4. DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR 5. MOLD FLASH SHALL NOT EXCEED 0.254mm 6. JEDEC PACKAGE REFERENCE IS MO-193
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Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
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LTC3250-1.5/LTC3250-1.2
TYPICAL APPLICATIO
Multiple High Efficiency Outputs from Single Li-Ion Battery
5 Li-Ion 1F 1 VIN VOUT LTC3200-5 3 6 SHDN C+ 2 GND 4 C- 6 3 10H 340k 22F 1F 5V 100mA 1F
OFF ON 1F
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PART NUMBER LTC1514 LTC1515 LT1776 DESCRIPTION 50mA, 650kHz, Step Up/Down Charge Pump with Low Battery Comparator 50mA, 650kHz, Step Up/Down Charge Pump with Power On Reset 500mA (IOUT), 200kHz, High Efficiency Step-Down DC/DC Converter COMMENTS VIN: 2.7V to 10V, VOUT: 3V/5V, Regulated Output, IQ: 60A, ISD: 10A, S8 Package VIN: 2.7V to 10V, VOUT: 3.3V or 5V, Regulated Output, IQ: 60A, ISD: <1A, S8 Package 90% Efficiency, VIN: 7.4V to 40V, VOUT(MIN): 1.24V, IQ: 3.2mA, ISD: 30A, N8,S8 Packages 75% Efficiency, VIN: 2.7V to 5.5V, VOUT: 1.5V/1.8V, Regulated Output, IQ: 180A, ISD: 10A, MS8 Package Up to 90% Efficiency, VIN: 2.7V to 5.5V, VOUT: 0.9V to 1.6V, Regulated Output, IQ: 9A, ISD: <1A, MS Package Up to 90% Efficiency, VIN: 2.7V to 5.5V, VOUT: 0.9V to 1.6V, IQ: 60A, ISD: <1A, DFN Package 95% Efficiency, VIN: 2.7V to 6V, VOUT(MIN): 0.8V, IQ: 20A, ISD: <1A, ThinSOT Package 95% Efficiency, VIN: 2.5 to 5.5V, VOUT(MIN): 0.6V, IQ: 20A, ISD: <1A, ThinSOT Package 95% Efficiency, VIN: 2.5V to 5.5V, VOUT(MIN): 0.8V, IQ: 60A, ISD: <1A, MS Package 95% Efficiency, VIN: 2.5V to 5.5V, VOUT(MIN): 0.8V, IQ: 60A, ISD: <1A, TSSOP16E Package 95% Efficiency, VIN: 2.5V to 5.5V, VOUT: 2.5V to 5.5V, IQ: 25A, ISD: <1A, MS Package 95% Efficiency, VIN: 2.4V to 5.5V, VOUT: 2.4V to 5.25V, IQ: 25A, ISD: <1A, DFN Package
3250fa LT/TP 1203 1K REV A * PRINTED IN USA
LTC1911-1.5/LTC1911-1.8 250mA,1.5MHz, High Efficiency Step-Down Charge Pump LTC3251 LTC3252 LTC3405/LTC3405A LTC3406/LTC3406B LTC3411 LTC3412 LTC3440 LTC3441 500mA, Spread Spectrum, High Efficiency Step-Down Charge Pump Dual 250mA (IOUT), Spread Spectrum, Inductorless (CS), Step-Down DC/DC Converter 300mA (IOUT), 1.5MHz, Synchronous Step-Down DC/DC Converter 600mA (IOUT), 1.5MHz, Synchronous Step-Down DC/DC Converter 1.25A (IOUT), 4MHz, Synchronous Step-Down DC/DC Converter 2.5A (IOUT), 4MHz, Synchronous Step-Down DC/DC Converter 600mA (IOUT), 2MHz, Synchronous Buck-Boost DC/DC Converter 1.2A (IOUT), 1MHz, Synchronous Buck-Boost DC/DC Converter
12
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900
q
FAX: (408) 434-0507 q www.linear.com
U
7 10F 2 8 60k 1 5 VIN OUT 3.3V 500mA MODE SW1 LTC3440 4 SHDN SW2 RT GND FB VC 9 10 300pF 6 VIN OUT LTC1911-1.8 7 8 SHDN C1+ 1 10F 2 1F 3 C2+ C2- C1- GND 5 4 1F 120k 1.8V 250mA 10F 200k 1 3 VIN SHDN OUT C+ C- 5 6 1F 4
3250-1.5 TA04
1.5V 250mA 4.7F
LTC3250-1.5 2 GND
(c) LINEAR TECHNOLOGY CORPORATION 2001

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