Instruction/ maintenance manual of the product ADP1148 Analog Devices
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REV. A Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties which may result from its use.
–2– REV. A ADP1148, ADP1148-3.3, ADP1148-5–SPECIFICA TIONS ELECTRICAL CHARACTERISTICS Parameter Symbol Conditions 2 Min Typ Max Units FEEDBACK VOLTAGE ADP1148 Only V 10 V IN = 9 V 1.21 1.25 1.29 V FEEDBACK CURRENT ADP1148 Only I 10 0.2 1.0 µ A REGULATED OUTPUT VOLTAGE V OUT V IN = 9 V ADP1148-3.
–3– REV. A ADP1148, ADP1148-3.3, ADP1148-5 ELECTRICAL CHARACTERISTICS Parameter Symbol Conditions 2 Min Typ Max Units FEEDBACK VOLTAGE ADP1148 Only V 10 V IN = 9 V 1.20 1.25 1.30 V REGULATED OUTPUT VOLTAGE V OUT V IN = 9 V ADP1148-3.3 I LOAD = 700 mA 3.
ADP1148, ADP1148-3.3, ADP1148-5 –4– REV. A CAUTION ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on the human body and test equipment and can discharge without detection. Although the ADP1148, ADP1148-3.
T ypical Per formance Characteristics–ADP1148, ADP1148-3.3, ADP1148-5 –5– REV. A MAXIMUM OUTPUT CURRENT – A 200 0 0 5 123 4 150 100 50 R SENSE – m V Figure 3. Selecting R SENSE vs. Maxi- mum Output Current OUTPUT CURRENT – A EFFICIENCY/LOSS – % 100 95 80 0.
(V IN –V OUT ) – V 12 NORMALIZED FREQUENCY 12 468 1 0 1.8 1.6 0.0 0.8 0.6 0.4 0.2 1.4 1.0 1.2 0 8 C 25 8 C 70 8 C Figure 12. Operating Frequency vs. (V IN –V OUT ) TEMPERATURE – 8 C 155 120 0 100 25 70 85 150 145 140 135 SENSE VOLTAGE – mV 130 125 MAXIMUM THRESHOLD Figure 15.
ADP1148, ADP1148-3.3, ADP1148-5 –7– REV. A APPLICATIONS The ADP1148 uses a current-mode, constant off-time structure to switch a pair of external complementary N- and P-channel MOSFETs. The operating frequency of the device is deter- mined by the value of the external capacitor connected to the C T pin.
ADP1148, ADP1148-3.3, ADP1148-5 –8– REV. A As the operating frequency is increased, the gate charge losses will cause reduced efficiency (see Efficiency section). The full formula for operating frequency is given by: f = ( 1 – V OUT /V IN )/ t OFF where t OFF = 1.
ADP1148, ADP1148-3.3, ADP1148-5 –9– REV. A An additional 0.1 µ F – 1 µ F ceramic bypass capacitor is advised on V IN Pin 3 parallel with C IN .
ADP1148, ADP1148-3.3, ADP1148-5 –10– REV. A Design Example As a design example, assume V IN = 12 V (nominal), V OUT = 5 V, I MAX = 2 A, and f = 200 kHz, R SENSE . C T , and L can immedi- ately be calculated: R SENSE = 100 mV /2 = 50 m Ω t OFF = (1/200 kHz ) × [1 – (5/12)] = 2.
ADP1148, ADP1148-3.3, ADP1148-5 –11– REV. A Board Layout When laying out the printed circuit board, the following check list should be used to ensure proper operation of the ADP1148. These items are also illustrated graphically in the layout diagram of Figure 18.
ADP1148, ADP1148-3.3, ADP1148-5 –12– REV. A P-DRIVE NC V IN C T INT V CC I TH SENSE(–) N-DRIVE NC POWER GND SIGNAL GND SHUTDOWN V FB SENSE(+) ADP1148-3.3 C C 3300pF R C 1k V IRF7403 D1 10BQ040 V IN 4V TO 18V IRF7204 C IN 100 m F 20V *L 50 m H C OUT 220 m F 10V 3 2 AVX 1000pF **R SENSE 0.
ADP1148, ADP1148-3.3, ADP1148-5 –13– REV. A P-DRIVE NC V IN C T INT V CC I TH SENSE(–) N-DRIVE NC POWER GND SIGNAL GND SHUTDOWN V FB SENSE(+) ADP1148 C C 3300pF R C 1k V IRF7403 D1 10BQ040 V IN 5.2V TO 14V IRF7204 C IN 100 m F 20V *L 50 m H R1B 43k V 1% R2 56k V 1% C OUT 220 m F 10V 3 2 OS-CON 100pF 1000pF **R SENSE 0.
ADP1148, ADP1148-3.3, ADP1148-5 –14– REV. A OUTLINE DIMENSIONS Dimensions shown in inches and (mm). 14-Lead Plastic DIP (N-14) 14 17 8 0.795 (20.19) 0.725 (18.42) 0.280 (7.11) 0.240 (6.10) PIN 1 0.325 (8.25) 0.300 (7.62) 0.015 (0.381) 0.008 (0.204) 0.
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–16– C2219a–2–12/97 PRINTED IN U.S.A..
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