IR3721 International Rectifier, IR3721 Datasheet
IR3721
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IR3721 Summary of contents
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... Samples only Page Power Monitor IC with DESCRIPTION The IR3721 is a versatile power or current monitor IC for low-voltage DC-DC converters. The IR3721 monitors the inductor current in buck or multiphase converters using either a current sensing resistor or the inductor’s winding resistance (DCR). The output (DI pulse code modulated signal whose duty ratio is proportional to the inductor current ...
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... DATA SHEET ≤ T ≤ 125 C, 0.5 ≤ Vo ≤ 1.8 V, and J MIN TYP MAX 3.10 2.4 75 350 450 1.452 1.493 1.535 25.5 0.5 =600 Ω CS2 =600 Ω, CS2 435 512 589 -0.5 +0.5 -250 +250 0.5 1250 2000 3000 IR3721 UNIT μA V kΩ 1 kHz mV nA 1.8 V Ω 07/14/08 ...
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... GND programs thermal monitor T Bias return and signal reference IC bias supply Connect to pin 4 Connect to pin 4 Power Monitor output; connect to output filter Connect to fixed voltage or VO, multiplied become analog output Connect to pin 5 Connect to pin 4 www.irf.com IR3721 DATA SHEET VK DI 07/14/08 ...
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... IC PIN FUNCTIONS VDD PINS www.datasheet4u.com These pins provide operational bias current to circuits internal to the IR3721. Bypass them with a high quality ceramic capacitor to the GND pins. GND PINS These pins return operational bias current to system ground measured with respect to GND. The ...
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... product of full-scale voltage and full scale current DCR VO C CS1 C CS2 VCS R CS2 Figure 1 Functional Description Diagram www.irf.com IR3721 DATA SHEET . L as shown in the figure then the K that can be measured is the FS VDD VK DI Power IR3721 GND 07/14/08 Vo ...
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... Equation 2 may be rewritten as a new function of temperature using equations 2 and 4 as follows: With Rs and Rp as additional free variables, use a spreadsheet to solve equation 5 for the desired full scale current while minimizing the I over temperature. www.irf.com IR3721 DATA SHEET ⎛ ⎞ ⎛ ⎞ ⎜ ...
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... TYPICAL 2-PHASE DCR SENSING APPLICATION The IR3721 is capable of monitoring power in a multiphase converter. A Two Phase DCR Sensing Circuit is shown below. The voltage output of any www.datasheet4u.com phase is equal to that of any and every other phase because they are electrically connected and monitored before. ...
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... Because the value of the shunt resistance does not change with temperature as the inductor DCR does, R can be a fixed resistor. T and C do CS2 CS2 I L SHUNT DCR L R CS2 C CS2 VDD VCS IR3721 V RT GND Figure 4 Resistor Sensing Circuit www.irf.com IR3721 DATA SHEET Power 07/14/08 ...
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... Filter the DI output with an RC filter to give a stable www.datasheet4u.com analog representation of the current or power. Some of the DI source resistance of this filter is internal to the IR3721 and specified in the electrical specifications table. Add twenty thousand to fifty thousand additional ohms externally to minimize resistance variation. As the DI source resistance ...
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... R SUM . eq ) CS1 = and SUM CS1 CS2 ). Calculate R CS2 CS1 ⎞ R ⎟ eq ⋅ 4 ⎟ R SUM ⎟ and 2 ⎟ ⎟ ⎟ ⎠ ⎞ R ⎟ eq ⋅ ⎟ R SUM ⎟ 2 ⎟ ⎟ ⎟ ⎠ . The value of CS2 to CS2 www.irf.com IR3721 DATA SHEET 07/14/08 ...
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... Place the capacitor Ccs2 close to the VO and VCS pins of the IR3721. Treat VO and VCS as a differential signal pair back to the IC as shown in the elliptical area designated #1 of figure 8. 2. Sense the inductor (or shunt) Kelvin style at its terminals ...
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... Figure 8 Layer 1 Figure 9 Layer 2 Page Figure 10 Layer 3 Figure 11 Layer 4 www.irf.com IR3721 DATA SHEET 07/14/08 ...
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... PCB PAD AND COMPONENT PLACEMENT Figure 12 below shows suggested pad and component placement. www.datasheet4u.com Figure 12 Pad placement Page www.irf.com IR3721 DATA SHEET 07/14/08 ...
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... SOLDER RESIST Figure 13 below shows suggested solder resist placement. www.datasheet4u.com Figure 13 Solder resist Page www.irf.com IR3721 DATA SHEET 07/14/08 ...
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... STENCIL DESIGN Figure 14 below shows a suggested stencil design. www.datasheet4u.com Figure 14 Stencil design Page www.irf.com IR3721 DATA SHEET 07/14/08 ...
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... Data and specifications subject to change without notice. This product has been designed and qualified for the Consumer market. Qualification Standards can be found on IR’s Web site. Visit us at www.irf.com for sales contact information. www.irf.com IR3721 DATA SHEET 3x3 MLPD INCHES NOM ...