LT3689EUD-5#PBF Linear Technology, LT3689EUD-5#PBF Datasheet

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... In window mode, the LT3689 monitors for WDI falling edges grouped too close together or too far apart. L, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. OUT BST 0.1µ ...

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... LT3689HMSE-5#PBF LT3689HMSE-5#TRPBF LT3689EUD#PBF LT3689EUD#TRPBF LT3689IUD#PBF LT3689IUD#TRPBF LT3689EUD-5#PBF LT3689EUD-5#TRPBF LT3689IUD-5#PBF LT3689IUD-5#TRPBF Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container. Consult LTC Marketing for information on non-standard lead based finish parts. For more information on lead free part marking, go to: ...

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ELECTRICAL CHARACTERISTICS junction temperature range, otherwise specifications are at T SYMBOL PARAMETER V Fixed Undervoltage Lockout IN V Overvoltage Lockout IN Quiescent Current from V IN Quiescent Current from OUT LT3689-5 Quiescent Current from V LT3689-5 Quiescent Current from OUT ...

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LT3689/LT3689-5 ELECTRICAL CHARACTERISTICS junction temperature range, otherwise specifications are at T SYMBOL PARAMETER t UV Detect to RST Asserted UV WDI Input Threshold WDI Input Pull-Up Current WDI Input Pulse Width W/T Threshold Voltage W/T Input Pull-Down Current WDE Threshold ...

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TYPICAL PERFORMANCE CHARACTERISTICS No-Load Supply Current 140 T = 25°C A 120 100 INPUT VOLTAGE (V) 3689 G04 Maximum V for Full Frequency IN ...

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LT3689/LT3689-5 TYPICAL PERFORMANCE CHARACTERISTICS BST Pin Current 125° –50° 25° 200 400 600 800 1000 SWITCH CURRENT (mA) 3689 G13 Switching Frequency vs R ...

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TYPICAL PERFORMANCE CHARACTERISTICS EN/UVLO Pin Current –50° 25° 150° (V) EN/UVLO 3689 G22 EN/UVLO Hysteresis ...

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LT3689/LT3689-5 TYPICAL PERFORMANCE CHARACTERISTICS Transient Duration vs POR Comparator Overdrive 800 700 600 500 RESET OCCURS ABOVE THE CURVE 400 300 200 100 0 0.10 1.00 10.00 100.00 POR COMPARATOR OVERDRIVE VOLTAGE AS PERCENTAGE OF RESET THRESHOLD, V (%) RST ...

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PIN FUNCTIONS BST: The BST pin is used to provide drive voltage higher than the input voltage to the internal NPN power switch The V pin supplies current to the LT3689’s internal IN IN circuitry and to the ...

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LT3689/LT3689-5 BLOCK DIAGRAM INTERNAL 0.8V REF EN/UVLO SYNC SOFT-START V OUT OUT LT3689-5 ERROR AMP ONLY R1 525k FB R2 100k WDE WDI W/T + 80mV FB – – ...

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TIMING DIAGRAMS WDI WDO t < t WDL WDI WDO t = TIME REQUIRED TO ASSERT RST LOW ONCE PROGRAMMED RESET PERIOD RST t = WATCHDOG UPPER BOUNDARY PERIOD WDU t = WATCHDOG WINDOW MODE LOWER ...

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LT3689/LT3689-5 OPERATION The LT3689 is a constant-frequency, current mode step- down regulator with a watchdog and a reset timer that allows microprocessor supervisory functions. Operation can be best understood by referring to the Block Diagram. Keeping the EN/UVLO pin at ...

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APPLICATIONS INFORMATION The output voltage is programmed with a resistor divider between the output and the FB pin. Choose 1% resistors according to: V OUT R1 0.8V For reference designators, refer to the Block Diagram. Setting the Switching ...

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LT3689/LT3689-5 APPLICATIONS INFORMATION Maximum Operating Voltage The maximum input voltage for LT3689 applications depends on switching frequency, the absolute maximum ratings of the V and BST pins, and by the minimum IN duty cycle (DC ). The LT3689 can operate ...

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APPLICATIONS INFORMATION this condition and forces the switch to turn off, allowing the inductor current to charge up the boost capacitor. This places a limitation on the maximum duty cycle. The maximum duty cycle that the LT3689 can sustain is ...

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... Low inductance may result in discontinuous mode operation, which is okay but further reduces maximum load current. For details of maximum output current and discontinuous mode operation, see Linear Technology Application Note 44. Finally, for duty cycles greater than 50 > ...

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... LT3689 circuit is plugged into a live supply, the input volt- age can ring to twice its nominal value, possibly exceeding the LT3689’s voltage rating. For a complete discussion, see Linear Technology’s Application Note 88. Output Capacitor and Output Ripple The output capacitor has two essential functions. Along with the inductor, it filters the square wave generated by the LT3689 to produce the DC output ...

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LT3689/LT3689-5 APPLICATIONS INFORMATION Table 4. Diode Vendors V R PART NUMBER (V) On Semiconductor MBRM120E 20 MBRM140 40 Diodes Inc. B120 20 B130 30 B140 40 B0540W 40 B140HB 40 Ceramic Capacitors Ceramic capacitors are small, robust and have very ...

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APPLICATIONS INFORMATION Most applications running require a small phase lead capacitor, ranging from 2pF to about 30pF , between the FB pin and V response. The circuits in the Typical Applications section use the appropriate phase lead ...

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LT3689/LT3689-5 APPLICATIONS INFORMATION BST and OUT Pin Considerations Capacitor C3 and the internal boost Schottky diode (see the Block Diagram) are used to generate a boost voltage that is higher than the input voltage. In most cases, a 0.1µF capacitor ...

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APPLICATIONS INFORMATION Another way to lower the start-up voltage is by using a resistor divider on the EN/UVLO pin (see the Shutdown and Undervoltage Lockout section). A resistor divider on EN/UVLO pin programs the turn-on threshold to slightly higher than ...

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LT3689/LT3689-5 APPLICATIONS INFORMATION Synchronization To select low ripple Burst Mode operation, tie the SYNC pin below 0.3V (this can be ground or a logic output). Synchro- nizing the LT3689 oscillator to an external frequency can be done by connecting a ...

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APPLICATIONS INFORMATION Example: switching should not start until the input is above 4.40V, and is to stop if the input falls below 4V 4.40V 4.40V − − 95.3k 4µA ...

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LT3689/LT3689-5 APPLICATIONS INFORMATION In both watchdog modes, when WDO is asserted, the reset timer is enabled. Any WDI pulses that appear while the reset timer is running are ignored. When the reset timer expires, the WDO is allowed to go ...

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APPLICATIONS INFORMATION is limited by the largest available low leakage capacitor. The accuracy of the timeout period will be affected by capacitor leakage (the nominal charging current is 2µA) and capacitor tolerance. A low leakage ceramic capacitor is recommended. Selecting ...

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LT3689/LT3689-5 APPLICATIONS INFORMATION LT3689’s output. If the V pin is allowed to float and the IN EN/UVLO pin is held high (either by a logic signal or be- cause it is tied then the LT3689’s internal circuitry ...

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... The die temperature is calculated by multiplying the LT3689 power dissipation by the thermal resistance from junction-to-ambient. Other Linear Technology Publications Application Notes 19, 35 and 44 contain more detailed descriptions and design information for buck regulators and other switching regulators. The LT1376 data sheet has a more extensive discussion of output ripple, loop compensation and stability testing ...

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LT3689/LT3689-5 TYPICAL APPLICATIONS 4.5V TO 36V TRANSIENT TO 60V WATCHDOG_DEFEAT µP I/O I/O RESET C6 10nF t WDU L1: CDR125NP-12MC D1: MBRM140 C1, C2, C3: X7R or X5R 6.3V TO 18V TRANSIENT TO 60V WATCHDOG_DEFEAT µP I/O I/O RESET C6 ...

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PACKAGE DESCRIPTION 2.845 ± 0.102 (.112 ± .004) 5.23 (.206) MIN 0.305 ± 0.038 (.0120 ± .0015) TYP RECOMMENDED SOLDER PAD LAYOUT DETAIL “A” 0.254 (.010) GAUGE PLANE 0.18 (.007) NOTE: 1. DIMENSIONS IN MILLIMETER/(INCH) 2. DRAWING NOT TO SCALE ...

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LT3689/LT3689-5 PACKAGE DESCRIPTION 3.50 ± 0.05 1.45 ± 0.05 (4 SIDES) 2.10 ± 0.05 RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS 3.00 ± 0.10 PIN 1 TOP MARK (NOTE 6) NOTE: 1. DRAWING CONFORMS TO JEDEC PACKAGE OUTLINE MO-220 VARIATION (WEED-2) ...

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... Replaced Figure 12 in the Applications Information section. 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 representa- tion that the interconnection of its circuits as described herein will not infringe on existing patent rights. ...

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... OUT(MIN 0.8V 75mA, I <1µA, 3mm × 3mm OUT(MIN 1.26V 850µA, I <1µA, 3mm × 3mm OUT(MIN 0.78V 70µA, I <1µA, 3mm × 3mm OUT(MIN 0211 REV D • PRINTED IN USA  LINEAR TECHNOLOGY CORPORATION 2010 3689fd ...