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LTC1503-1.8/LTC1503-2 High Efficiency Inductorless Step-Down DC/DC Converters
FEATURES
s s s s s s s s s s s s
DESCRIPTIO
Input Voltage Range: 2.4V to 6V Fixed Output Voltages: 1.8V 4%, 2V 4% Output Current: Up to 100mA No Inductors Typical Efficiency 25% Higher than LDOs Low Operating Current: 25A Low Shutdown Current: 5A 600kHz Switching Frequency Shutdown Disconnects Load from VIN Soft-Start Limits Inrush Current at Turn-On Short-Circuit and Overtemperature Protected Available in 8-Pin MSOP and SO Packages
The LTC(R)1503-1.8/LTC1503-2 are switched capacitor step-down DC/DC converters that produce a regulated output from a 2.4V to 6V input. The parts use switched capacitor fractional conversion to achieve high efficiency over the entire input range. No inductors are required. Internal circuitry controls the step-down conversion ratio to optimize efficiency as the input voltage and load conditions vary. Typical efficiency is 25% higher than that of a low dropout (LDO) linear regulator. Regulation is achieved by sensing the output voltage and enabling the internal switching network as needed to maintain a fixed output voltage. This method of regulation enables the parts to achieve high efficiency at extremely light loads. Low operating current (25A with no load, 5A in shutdown) and low external parts count (two 1F flying capacitors and two 10F bypass capacitors) make the LTC1503-1.8/LTC1503-2 ideally suited for space constrained battery-powered applications. The parts are fully short-circuit and overtemperature protected. The LTC1503-1.8/LTC1503-2 are available in 8-pin MSOP and SO packages.
, LTC and LT are registered trademarks of Linear Technology Corporation.
APPLICATIO S
s s s s s
s
Cellular Phones Handheld Computers Smart Card Readers Low Power DSP Supplies Portable Electronic Equipment Handheld Medical Instruments
TYPICAL APPLICATIO
Single Li-Ion to 2V DC/DC Converter
80
4 1-CELL Li-Ion OR 3-CELL NiMH 10F 1F 2 3 5
VIN C1- C1+
VOUT C2 +
1 10F 1F
8 C2 - 6 7
VOUT = 2V IOUT = 100mA
EFFICIENCY (%)
LTC1503-2
SHDN/SS GND
1503-1.8/2 TA01
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Efficiency vs Input Voltage
100 IOUT = 100mA IOUT = 1mA 60 "IDEAL" LDO 40 LTC1503-2 VOUT = 2V 20 2 3 4 INPUT VOLTAGE (V)
1503-1.8/2 TA02
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5
6
1
LTC1503-1.8/LTC1503-2
ABSOLUTE
AXI U
RATI GS
VIN, C1+, C1-, C2 +, C2 - to GND ............... - 0.3V to 6.5V SHDN/SS to GND ......................... - 0.3V to (VIN + 0.3V) VOUT Short-Circuit Duration ............................. Indefinite Commercial Temperature Range ............ - 40C to 85C
PACKAGE/ORDER I FOR ATIO
TOP VIEW VOUT C1- C1+ VIN 1 2 3 4 8 7 6 5 C2 - GND C2+ SHDN/SS
ORDER PART NUMBER LTC1503CMS8-1.8 LTC1503CMS8-2 MS8 PART MARKING LTFX LTHN
VOUT 1 C1- 2 C1+ 3 VIN 4
MS8 PACKAGE 8-LEAD PLASTIC MSOP
TJMAX = 125C, JA = 200C/W
Consult factory for Military grade parts.
ELECTRICAL CHARACTERISTICS
The q denotes specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. VIN = VIN(MIN) to VIN(MAX), C1 = C2 = 1F, CIN = COUT = 10F unless otherwise noted.
PARAMETER VIN Operating Voltage VOUT VIN Operating Current VIN Shutdown Current Output Ripple Voltage Efficiency Switching Frequency SHDN/SS Input Threshold SHDN/SS Input Current VOUT Short-Circuit Current VOUT Turn-On Time VSHDN/SS = 0V (Note 3) VSHDN/SS = VIN VOUT = 0V (Note 4) CSS = 0nF, VIN = 3.6V, COUT = 10F CSS = 10nF LTC1503-1.8, 0mA < IOUT < 100mA LTC1503-2, 0mA < IOUT < 100mA IOUT = 0mA SHDN/SS = 0V LTC1503-X, VIN = 3.6V, IOUT = 100mA LTC1503-2, VIN = 3.6V, IOUT = 100mA Oscillator Free Running
q q q q
CONDITIONS
q q q q q
Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: The LTC1503C is guaranteed to meet specified performance from 0C to 70C and is designed, characterized and expected to meet these extended temperature limits, but are not tested at - 40C and 85C. The LTC1503I is guaranteed to meet the extended temperature limits.
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(Note 1)
Industrial Temperature Range ............... - 40C to 85C Specified Temperature Range (Note 2) ... - 40C to 85C Storage Temperature Range ................ - 65C to 150C Lead Temperature (Soldering, 10 sec)................. 300C
TOP VIEW 8 C2 - 7 GND 6 C2+ 5 SHDN/SS
ORDER PART NUMBER LTC1503CS8-1.8 LTC1503CS8-2 LTC1503IS8-1.8 LTC1503IS8-2 S8 PART MARKING 150318 15032 503I18 1503I2
S8 PACKAGE 8-LEAD PLASTIC SO TJMAX = 125C, JA = 150C/W
MIN 2.4 1.728 1.920
TYP 1.8 2.0 25 5 25 82.9 600
MAX 6 1.872 2.080 50 10
UNITS V V V A A mVP-P % kHz
0.2 - 3.5 -1 8
0.35 -2 22 0.1 8
0.5 -1 1 50
V A A mA ms ms
Note 3: Currents flowing into the device are positive polarity. Currents flowing out of the device are negative polarity. Note 4: When VOUT is less than 150mV, IOUT is limited to much less than the maximum rated output current to prevent damage to the output devices.
LTC1503-1.8/LTC1503-2 TYPICAL PERFOR A CE CHARACTERISTICS
LTC1503-X Input Operating Current vs Input Voltage
50 IOUT = 0mA 10
INPUT SHUTDOWN CURRENT (A)
TA = -40C 5 TA = 25C TA = 85C
OUTPUT VOLTAGE (V)
INPUT CURRENT (A)
40
30 TA = 25C 20
TA = -40C TA = 85C
10
2
3
4 INPUT VOLTAGE (V)
LTC1503-2 Output Voltage vs Input Voltage
2.10 IOUT = 50mA 2.05
EFFICIENCY (%)
OUTPUT VOLTAGE (V)
TA = -40C 2.00 TA = 85C TA = 25C 1.95
IOUT = 1mA 60 "IDEAL" LDO 40
EFFICIENCY (%)
1.90
2
3
4 INPUT VOLTAGE (V)
5
LTC1503-2 Efficiency vs Output Current
100 TA = 25C 1.84
80
OUTPUT VOLTAGE (V)
EFFICIENCY (%)
TA = -40C 1.80 TA = 85C 1.78 TA = 25C
OUTPUT VOLTAGE (V)
60
40 VIN = 5V VIN = 4.4V VIN = 3.6V VIN = 3V VIN = 2.4V 0.1 10 100 1 OUTPUT CURRENT (mA) 1000
20
0 0.01
UW
5
1503 G01
LTC1503-X Input Shutdown Current vs Input Voltage
1.90 VOUT = 0V VSHDN/SS = 0V 7.5 1.85
LTC1503-1.8 Output Voltage vs Input Voltage
IOUT = 50mA
TA = -40C 1.80 TA = 25C 1.75 TA = 85C
2.5
6
0
1.70 2 3 4 INPUT VOLTAGE (V)
1503-1.8/2 TA02
5
6
2
3
4 INPUT VOLTAGE (V)
5
6
1503-1.8/2 G03
LTC1503-1.8 Efficiency vs Input Voltage
100 TA = 25C
100
LTC1503-1.8 Efficiency vs Output Current
TA = 25C
IOUT = 100mA
80
80
60
40 VIN = 5V VIN = 4.4V VIN = 3.6V VIN = 3V VIN = 2.4V 0.1 10 100 1 OUTPUT CURRENT (mA) 1000
20
6
1503 G03
20
2
3
4 INPUT VOLTAGE (V)
5
6
1503-1.8/2 G05
0 0.01
1503-1.8/2 G06
LTC1503-1.8 Output Voltage vs Output Current
VIN = 3.3V
LTC1503-2 Output Voltage vs Output Current
2.04 VIN = 3.3V
1.82
2.02 TA = -40C 2.00 TA = 85C 1.98 TA = 25C
1.76
1.96
1.74 0.01
0.1
10 100 1 OUTPUT CURRENT (mA)
1000
1.94 0.01
0.1
10 100 1 OUTPUT CURRENT (mA)
1000
1503-1.8/2 G07
1503-1.8/2 G08
1503-1.8/2 G09
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LTC1503-1.8/LTC1503-2 TYPICAL PERFOR A CE CHARACTERISTICS
LTC1503-X Output Short-Circuit Current vs Input Voltage
40 VOUT SHORTED TO GND 100
OUTPUT CURRENT (mA)
TA = -40C 20 TA = 85C 10
START-UP TIME (ms)
30
0
2
Output Load Transient Response (LTC1503-1.8,1mA to 100mA Step)
100mA IOUT 50mA/DIV 1mA
VOUT 50mV/DIV AC COUPLED 1ms/DIV
1503-1.8/2 G12
PI FU CTIO S
VOUT (Pin 1): Regulated Output Voltage. VOUT is disconnected from VIN during shutdown. Bypass VOUT to ground with a 10F low ESR capacitor. C1 - (Pin 2): Flying Capacitor One Negative Terminal. C1 + (Pin 3): Flying Capacitor One Positive Terminal. VIN (Pin 4): Input Voltage. VIN may be between 2.4V and 6V. Bypass VIN to ground with a 10F low ESR capacitor. SHDN/SS (Pin 5): Shutdown/Soft-Start Control. The pin is designed to be driven with an external open-drain output. Holding the SHDN/SS pin below 0.25V will force the part into shutdown mode. An internal pull-up current of 2A will force the SHDN/SS voltage to climb to VIN once the device driving the pin is forced into a Hi-Z state. To limit inrush current on start-up, connect a capacitor between the SHDN/SS pin and ground. Capacitance on the SHDN/SS pin will limit the dV/dt of the pin during turnon which, in turn, will limit the dV/dt of VOUT. By selecting an appropriate soft-start capacitor for a known output capacitor, the user can control the inrush current during
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LTC1503-X Start-Up Time vs Soft-Start Capacitor
VIN = 3.6V
10 TA = -40C 1 TA = 25C TA = 85C 0.1
TA = 25C
4 INPUT VOLTAGE (V)
5
6
1503-1.8/2 G10
0.01 0.01
1 10 0.1 SOFT-START CAPACITOR (nF)
100
1503-1.8/2 G10
Output Ripple, COUT = 10F
Output Ripple, COUT = 22F
VOUT 10mV/DIV AC COUPLED
VOUT 10mV/DIV AC COUPLED
5s/DIV VIN = 3.6V VOUT = 2V IOUT = 100mA COUT = 10F CERAMIC
1503-1.8/2 G13
5s/DIV VIN = 3.6V VOUT = 2V IOUT = 100mA COUT = 22F CERAMIC
1503-1.8/2 G14
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LTC1503-1.8/LTC1503-2
PI FU CTIO S
turn-on (see Applications Information). If neither of the two functions are desired, the pin may be floated or tied to VIN. C2 + (Pin 6): Flying Capacitor Two Positive Terminal. GND (Pin 7): Ground. Connect to a ground plane for best performance. C2 - (Pin 8): Flying Capacitor Two Negative Terminal.
BLOCK DIAGRA
VIN CIN 680k
330k
990k
SHORT CIRCUIT
MODE SKIP
600kHz OSCILLATOR VIN 2A
REG ENABLE
COMP1
SOFT-START
350mV
VREF RAMP
SHDN/SS
+
SHDN
350mV
+
-
LTC1503-2
1503-1.8/2 BD
+
COMP2
-
-
-
+
+
+
+
-
+
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+ -
MODE CONTROL STEP-DOWN CHARGE PUMP
C1+
C1- C2 +
+ -
VOUT
C2 - VOUT COUT
+
150mV 800k
10mV
1.2M
1.2V VREF
GND
5
LTC1503-1.8/LTC1503-2
APPLICATIO S I FOR ATIO
General Operation The two most common methods for providing regulated step-down DC/DC conversion are linear DC/DC conversion (used by LDOs) and inductor-based DC/DC conversion. Linear regulation provides low cost and low complexity, but the conversion efficiency is poor since all of the load current must come directly from VIN. Inductor-based stepdown conversion provides the highest efficiency, but the solution cost and circuit complexity are much higher. The LTC1503-X provides the efficiency advantages associated with inductor-based circuits as well as the cost and simplicity advantages of an inductorless converter. The LTC1503-X is a switched capacitor step-down DC/DC converter. The part uses an internal switch network and fractional conversion ratios to achieve high efficiency over widely varying VIN and output load conditions. Internal control circuitry selects the appropriate step-down conversion ratio based on VIN, VOUT and load conditions to optimize efficiency. The part has three possible step-down modes: 2-to-1, 3-to-2 or 1-to-1 (gated switch) step-down mode. Only two external flying caps are needed to operate in all three modes. 2-to-1 mode is chosen when VIN is greater than two times the desired VOUT. 3-to-2 mode is chosen when VIN is greater than 1.5 times VOUT but less than 2 times VOUT. 1-to-1 mode is chosen when VIN falls below 1.5 times VOUT. An internal mode skip function will switch the step-down ratio as needed to maintain output regulation under heavy load conditions. Regulation is achieved by sensing the divided down output voltage and enabling the charge pump as needed to boost the output back into regulation. This method of regulation allows the LTC1503-X to achieve high efficiency at very light loads. The part has shutdown capability as well as user controlled inrush current limiting. In addition, the part can withstand an indefinite short-circuit condition on VOUT and is also overtemperature protected. Step-Down Charge Pump Operation Figure 1a shows the charge pump switch configuration that is used for 2-to-1 step down. When the charge pump is enabled in this mode, a two phase nonoverlapping clock generates the switch control signals. On phase one of the clock, flying capacitor C1 is connected through switches
VIN C1 (EXTERNAL) C1- S3 2
1503-1.8/2 F01a
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S4 2 C1+ S1 1 VOUT S2 1
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Figure 1a. Step-Down Charge Pump in 2-to-1 Mode
S1 and S2 across VOUT. If the voltage on C1 is greater than the voltage on COUT, charge is transferred from C1 onto COUT. On phase two, the top plate of C1 is connected to VIN and the bottom plate is connected to VOUT. If the voltage across C1 is less than VIN /2 during phase two, charge will be transferred from C1 onto COUT thereby boosting the voltage on COUT and raising the voltage across C1. Thus, in 2-to-1 mode, charge transfer from C1 onto COUT occurs on both phases of the clock, and the voltage on COUT is driven towards 1/2VIN until the output is back in regulation. Since charge current is sourced from ground on phase one of the clock, current multiplication is realized with respect to VIN, i.e., IVOUT equals approximately 2 * IVIN. This results in significant efficiency improvement relative to a linear regulator. The 3-to-2 conversion mode also uses a nonoverlapping clock for switch control but requires two flying capacitors and a total of seven switches (see Figure 1b). On phase one, C1 and C2 are connected in series across VOUT. If the sum of the voltages across C1 and C2 is greater than VOUT, charge is transferred from the flying caps onto COUT thereby reducing the average voltage on the flying caps and raising the voltage on the output capacitor. On phase two, the two flying capacitors are connected on parallel between VIN and VOUT. Since the average voltage across the two capacitors during phase one is VOUT /2, charge will be transferred from VIN to VOUT through the two flying caps if VIN minus VOUT /2 is greater than VOUT. In this manner, charge is again transferred from the flying caps to the output on both phases of the clock, and the voltage on COUT is driven towards (2/3)VIN until the part is back in regulation. As in 2-to-1 mode, charge current is sourced from ground on phase one of the clock which results in increased power efficiency. IVOUT in 3-to-2 mode equals approximately (3/2)IVIN.
LTC1503-1.8/LTC1503-2
APPLICATIO S I FOR ATIO
S5 2 VIN C1 (EXTERNAL) S4 C1- 2 C1+ S1 1 VOUT
S7 2
S2 1
C2 + C2 (EXTERNAL) S6 C2 - 2
S3 1 GND
1503-1.8/2 F01b
Figure 1b. Step-Down Charge Pump in 3-to-2 Mode
In 1-to-1 mode, switch S1 and S2 are connected in series between VIN and VOUT as needed to boost VOUT back into regulation (see Figure 1c). The REG ENABLE signal from the main comparator (COMP1) controls switches S1 and S2 directly. Since all of the VOUT current is sourced from VIN, the efficiency in 1-to-1 mode is approximately equal to that of a linear regulator.
S2 VIN C1 (EXTERNAL) C1-
1503-1.8/2 F01c
C1+
S1 VOUT
Figure 1c. Step-Down Charge Pump in 1-to-1 Mode
Mode Selection and Mode Skipping The optimal step-down conversion mode is chosen based on VIN to VOUT differential voltage and output load conditions. Two internal comparators are used to select the default step-down mode based on the VIN and VOUT voltage. A separate comparator (COMP2) is used to sense a droop on VOUT due to a heavy output load and force the charge pump to skip to a higher output current mode to
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maintain regulation. This will only occur as VIN/VOUT nears a 3-to-2 or 1-to-1 transition point. For example, under light load conditions, the LTC1503-X can operate in 2-to-1 mode when VIN equals 4.1V with greater than 90% efficiency. However, when the load is increased, the part can no longer supply enough output current in 2-to-1 mode to maintain regulation. This causes VOUT to droop below the regulation point until COMP2 trips and forces the part to skip from 2-to-1 mode to 3-to-2 mode. The COMP2 threshold is about 17mV (VOUT referred) below the main comparator regulation point. Hysteresis in COMP2 will force the part to transition in and out of mode skipping. This will result in a slight VOUT decrease of approximately 20mV under mode skipping conditions. Shutdown/Soft-Start Operation The SHDN/SS pin is used to implement both low current shutdown and soft-start. The soft-start feature limits inrush currents when the regulator is initially powered up or taken out of shutdown. Forcing a voltage lower than 0.35V (typ) will put the part into shutdown mode. Shutdown mode disables all control circuitry and forces the charge pump VOUT into a high impedance state. A 2A pullup current on the SHDN/SS pin will force the part into active mode if the pin is left floating or is driven with an open-drain output that is in a high impedance state. If the pin is not driven with an open-drain device, it must be forced to a logic high voltage of 2.2V (min) to ensure proper VOUT regulation. The SHDN/SS pin should not be driven to a voltage higher than VIN. To implement soft-start, the SHDN/SS pin must be driven with an open-drain device and a capacitor must be connected from the SHDN/SS pin to GND. Once the opendrain device is turned off, a 2A pull-up current will begin charging the external SS capacitor and force the voltage on the pin to ramp towards VIN. As soon as the SHDN threshold is reached (0.35V typ), the internal reference voltage which controls the VOUT regulation point will follow the ramp voltage on the SHDN/SS pin (minus a 0.35V offset to account for the SHDN threshold) until the reference reaches its final band gap voltage. This occurs when the voltage on the SHDN/SS pin reaches
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LTC1503-1.8/LTC1503-2
APPLICATIO S I FOR ATIO
approximately 1.9V. Since the ramp rate on the SHDN/SS pin controls the ramp rate on VOUT, the average inrush current can be controlled through selection of CSS and COUT. For example, a 4.7nF capacitor on SHDN/SS results in a 4ms ramp time from 0.35V to 1.9V on the pin. If COUT is 10F, the 4ms VREF ramp time results in an average COUT charge current of only 5mA (see Figure 2c).
VOUT LTC1503-X 5 ON OFF VCTRL CSS SHDN/SS
1503-1.8/2 F02a
1 RLOAD
(a)
VCTRL 2V/DIV
VOUT 1V/DIV
LTC1503-2 CSS = 0nF COUT = 10F RLOAD = 50
2ms/DIV
1503-1.8/2 F02b
(b)
VCTRL 2V/DIV
VOUT 1V/DIV
LTC1503-2 CSS = 4.7nF COUT = 10F RLOAD = 50
2ms/DIV
1503-1.8/2 F02b
(c)
Figure 2. Shutdown/Soft-Start Operation
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Capacitor Selection For best performance, it is recommended that low ESR capacitors be used for CIN and COUT to reduce noise and ripple. If the ESR of the output capacitor is too high (> 0.5), both efficiency and output load regulation may be degraded. The CIN and COUT capacitors should be either ceramic or tantalum and should be 10F or greater. If the input source impedance is very low (< 0.5), CIN may not be needed. Ceramic capacitors are recommended for the flying caps C1 and C2 with values of 0.47F to 2.2F. Smaller values may be used in low output current applications (e.g., IOUT < 10mA). For best performance choose the same capacitance value for both C1 and C2. Output Ripple Normal LTC1503-X operation produces voltage ripple on the VOUT pin. Output voltage ripple is required for the parts to regulate. Low frequency ripple exists due to the hysteresis in the sense comparator and propagation delays in the charge pump enable/disable circuits. High frequency ripple is also present mainly from the ESR (equivalent series resistance) in the output capacitor. Typical output ripple (VIN = 3.6V) under maximum load is 25mV peak-to-peak with a low ESR 10F output capacitor. The magnitude of ripple voltage depends on several factors. High input voltages increase the output ripple since more charge is delivered to COUT per charging cycle. Large output current load and/or a small output capacitor (< 10F) results in higher ripple due to higher output voltage dV/dt. High ESR capacitors (ESR > 0.5) on the output pin cause high frequency voltage spikes on VOUT with every clock cycle. There are several ways to reduce the output voltage ripple (see Figure 3). A larger COUT capacitor (22F or greater) will reduce both the low and high frequency ripple due to the lower COUT charging and discharging dV/dt and the lower ESR typically found with higher value (larger case size) capacitors. A low ESR ceramic output capacitor will minimize the high frequency ripple, but will not reduce the low frequency ripple unless a high capacitance value is chosen. A reasonable compromise is to use a 10F to 22F tantalum capacitor in parallel with a 1F to 3.3F ceramic
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LTC1503-1.8/LTC1503-2
APPLICATIO S I FOR ATIO
capacitor on VOUT to reduce both the low and high frequency ripple. An RC filter may also be used to reduce high frequency voltage spikes.
LTC1503-X VOUT
+
VOUT 10F TANTALUM 0.5 1F CERAMIC
LTC1503-X VOUT
+
10F TANTALUM
+
VOUT 10F TANTALUM
1503-1.8/2 F03
Figure 3. Output Ripple Reduction Techniques
COUT
Protection Features The LTC1503-X contains both thermal shutdown and short-circuit protection features. The charge pump will shut down when the junction temperature reaches approximately 150C and will resume operation once the junction temperature has dropped back to 125C. The part will limit output current to 20mA (typ) when a short-circuit condition (VOUT < 150mV) exists to prevent damage to the internal switches. During start-up, the 20mA current limit
VOUT C1 VIN LTC1503-X C2 GND SHDN/SS
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is disabled once VOUT reaches 0.7V (typ). The part can survive an indefinite short from VOUT to GND. Layout Considerations For best regulation and noise performance, careful board layout is required. Improper bypassing and grounding may lead to poor load regulation and output ripple performance. All capacitors, especially CIN and COUT, must be as close as possible to the VIN and VOUT pins. Connecting the GND pin and all bypass capacitors to an uninterrupted ground plane is also advised. See Figure 4 for recommended component placement and grounding.
CIN
1503-1.8/2 F04
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Figure 4. Recommended Component Placement and Grounding
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LTC1503-1.8/LTC1503-2
PACKAGE DESCRIPTIO
0.007 (0.18) 0.021 0.006 (0.53 0.015)
* DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE ** DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS. INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
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Dimensions in inches (millimeters) unless otherwise noted.
MS8 Package 8-Lead Plastic MSOP
(LTC DWG # 05-08-1660)
0.118 0.004* (3.00 0.102)
8
76
5
0.193 0.006 (4.90 0.15)
0.118 0.004** (3.00 0.102)
1 0.040 0.006 (1.02 0.15) 0 - 6 TYP SEATING PLANE 0.012 (0.30) 0.0256 REF (0.65) BSC
23
4 0.034 0.004 (0.86 0.102)
0.006 0.004 (0.15 0.102)
MSOP (MS8) 1098
LTC1503-1.8/LTC1503-2
PACKAGE DESCRIPTIO U
Dimensions in inches (millimeters) unless otherwise noted.
S8 Package 8-Lead Plastic Small Outline (Narrow 0.150)
(LTC DWG # 05-08-1610)
0.189 - 0.197* (4.801 - 5.004) 8 7 6 5
0.228 - 0.244 (5.791 - 6.197)
0.150 - 0.157** (3.810 - 3.988)
1 0.010 - 0.020 x 45 (0.254 - 0.508) 0.008 - 0.010 (0.203 - 0.254) 0- 8 TYP
2
3
4
0.053 - 0.069 (1.346 - 1.752)
0.004 - 0.010 (0.101 - 0.254)
0.014 - 0.019 (0.355 - 0.483) TYP *DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE **DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
0.016 - 0.050 (0.406 - 1.270)
0.050 (1.270) BSC
SO8 1298
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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LTC1503-1.8/LTC1503-2
TYPICAL APPLICATIO
1-CELL Li-Ion OR 3-CELL NiMH
ON OFF
RELATED PARTS
PART NUMBER LTC1474/LTC1475 LTC1502-3.3 LTC1514/LTC1515 LTC1555/LTC1556 LTC1627 LTC1754-3.3 LTC1754-5 DESCRIPTION Low Quiescent Current Step-Down DC/DC Converter Single Cell to 3.3V Quadrupler Charge Pump Micropower, Regulated 5V Step-Up/Step-Down Charge Pump DC/DC Converters SIM Power Supply and Level Translator Monolithic Synchronous Buck Step-Down Switching Regulator 3.3V Charge Pump with Shutdown in SOT-23 5V Charge Pump with Shutdown in SOT-23 COMMENTS IOUT to 250mA, IQ = 10A; 8-Lead MSOP VIN = 0.9V to 1.8V, IOUT = 10mA; IQ = 40A 2V to 10V Input Range; Up to 50mA Output Current: Short-Circuit and Overtemperature Protected Step-Up/Step-Down Charge Pump Generates 5V or 3V 2.65V to 8.5V Input Range; VOUT from 0.8V, IOUT to 500mA; Low Dropout Operation; 100% Duty Cycle 50mA Output Current, ICC = 13A 50mA Output Current, ICC = 13A
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Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408)432-1900 q FAX: (408) 434-0507 q www.linear-tech.com
U
DC/DC Converter with Shutdown and Soft-Start
LTC1503-1.8 4 10F 1F 2 3 VIN C1- VOUT C2- 1 8 1F 10F VOUT = 1.8V IOUT = 100mA 6 C1+ C2+ 5 7 SHDN/SS GND 10nF 2N7002
1503-1.8/2 TA03
150312f LT/TP 0200 4K * PRINTED IN USA
(c) LINEAR TECHNOLOGY CORPORATION 1999

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