sc1485itstr Semtech Corporation, sc1485itstr Datasheet
sc1485itstr
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sc1485itstr Summary of contents
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POWER MANAGEMENT Description The SC1485 is a dual output constant-on synchronous buck PWM controller intended for use in notebook computers and other battery operated portable devices. Features include high efficiency and a fast dynamic response with no minimum on time. ...
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POWER MANAGEMENT Absolute Maximum Ratings Exceeding the specifications below may result in permanent damage to the device, or device malfunction. Operation outside of the parameters specified in the Electrical Characteristics section is not implied. Exposure to Absolute Maximum rated conditions ...
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POWER MANAGEMENT Electrical Characteristics (Cont.) Test Conditions 15V, EN/PSV1=EN/PSV2 = 5V, VCCA1 = VDDP1 = VCCA2 = VDDP2 = 5V, V BAT ...
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POWER MANAGEMENT Electrical Characteristics (Cont.) Test Conditions 15V, EN/PSV1=EN/PSV2 = 5V, VCCA1 = VDDP1 = VCCA2 = VDDP2 = 5V, V BAT ...
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POWER MANAGEMENT Pin Configuration TSSOP-28 Pin Descriptions ...
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POWER MANAGEMENT Pin Descriptions (Cont ...
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POWER MANAGEMENT Block Diagram VCCA1 (25) POR / SS EN/SPV1 (22) TON1 (23) TON VOUT1 (24) TOFF 1.5V REF FB1 (26) X3 PGD1 (27) VSSA1 (28) VCCA2 (11) POR / SS EN/SPV2 (8) TON2 (9) TON VOUT2 (10) TOFF 1.5V ...
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POWER MANAGEMENT Applications Information +5V Bias Supplies The SC1485 requires an external +5V bias supply in addition to the battery. If stand-alone capability is required, the +5V supply can be generated with an external linear regulator such as the Semtech ...
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POWER MANAGEMENT Output Voltage Selection The output voltage (OUT2 shown) is set by the feedback resistors R9 & R13 of Figure 2 below. The internal reference is 1.5V, so the voltage at the feedback pin is multiplied by three to ...
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POWER MANAGEMENT The current limit circuitry also protects against negative over-current (i.e. when the current is flowing from the load to PGND through the inductor and bottom MOSFET). In this case, when the bottom MOSFET is turned on, the phase ...
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POWER MANAGEMENT Be sure to include inductor resistance and MOSFET on- state voltage drops when performing worst-case dropout duty-factor calculations. SC1485 System DC Accuracy Two IC parameters affect system DC accuracy, the error comparator threshold voltage variation and the switching ...
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POWER MANAGEMENT V f OUT SW _ VBAT ( MAX ) V t BAT ( MAX ) ON _ VBAT ( MAX t is generated by a one-shot comparator that samples ON V via R , converting this to a ...
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POWER MANAGEMENT We will select a value of 12.5m design, which would be achieved by using two 25m output capacitors in parallel. Note that for constant-on converters there is a minimum ESR requirement for stability which can be calculated as ...
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POWER MANAGEMENT For our example 610µF. OUT(MIN) We will select 440µF, using two 220µF, 25m capacitors in parallel. For smaller load release overshoot, 660µF may be used. Alternatively, one 15m 220µF, 330µF or 470µF capacitor may be used ...
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POWER MANAGEMENT gives us 1100 10 5 150 250 300 182 W and ...
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POWER MANAGEMENT Layout Guidelines One (or more) ground planes is/are recommended to minimize the effect of switching noise and copper losses, and maximize heat dissipation. The IC ground references, VSSA1 and VSSA2, should be kept separate from power ground. All ...
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POWER MANAGEMENT The layout can be considered in two parts, the control section referenced to VSSA1/2 and the power section. Looking at the control section first, locate all components referenced to VSSA1/2 on the schematic and place these components at ...
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POWER MANAGEMENT In Figure 10, all components referenced to VSSA1 and VSSA2 have been placed and have been connected using 0.020” traces. Note that there are two separate traces, one for VSSA1 and one for VSSA2. Decoupling capacitors C9 and ...
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POWER MANAGEMENT U1 22 EN/PSV1 23 TON1 VOUT VOUT1 24 VOUT1 VCCA1 0402 0402 26 FB1 27 PGD1 R3 28 VSSA1 0402 VSSA1 8 EN/PSV2 9 TON2 VOUT2 VOUT 10 VOUT2 C15 R9 20k0 11 VCCA2 56p ...
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POWER MANAGEMENT Next, looking at the power section, the schematic in Figure 12 below shows the power section and input loop for OUT2: VBAT C14 C13 C12 10u/25V 0u1/25V 2n2/50V 1210 0603 0402 The schematic has been redrawn to emphasize ...
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POWER MANAGEMENT Key points for the power section: 1) there should be a very small input loop, well decoupled. 2) the phase node should be a large copper pour, but compact since this is the noisiest node. 3) input power ...
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POWER MANAGEMENT Typical Characteristics 1.2V Efficiency (Power Save Mode) vs. Output Current vs. Input Voltage 100 BAT 20V BAT (A) ...
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POWER MANAGEMENT Typical Characteristics (Cont.) Load Transient Response, Continuous Conduction Mode Load Transient Response, Continuous Conduction Mode Zoomed Load Transient Response, Continuous Conduction Mode Zoomed Please refer to Figure ...
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POWER MANAGEMENT Typical Characteristics (Cont.) Load Transient Response, Power Save Mode Load Transient Response, Power Save Mode Zoomed Load Transient Response, Power Save Mode Zoomed Please refer to Figure ...
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POWER MANAGEMENT Typical Characteristics (Cont.) Startup (PSV), EN/PSV Going High Startup (CCM), EN/PSV 0V to Floating Please refer to Figure 8 on Page 16 for test schematic (OUT2) 2005 Semtech Corp. Trace 1: 1.2V, 0.5V/div. Trace 2: LX, 10V/div Trace ...
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POWER MANAGEMENT Outline Drawing - TSSOP- E/2 PIN 1 INDICATOR ccc N/2 TIPS aaa C SEATING PLANE C SIDE VIEW NOTES: 1. CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES). 2. DATUMS ...
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... CONSULT YOUR MANUFACTURING GROUP TO ENSURE YOUR COMPANY'S MANUFACTURING GUIDELINES ARE MET. Contact Information Phone: (805)498-2111 FAX (805)498-3804 2005 Semtech Corp. DIM Semtech Corporation Power Management Products Division 200 Flynn Road, Camarillo, CA 93012 27 SC1485 DIMENSIONS INCHES MILLIMETERS (.222) (5.65) .161 4.10 .026 0.65 .016 ...