lx1668 Microsemi Corporation, lx1668 Datasheet
lx1668
Available stocks
Related parts for lx1668
lx1668 Summary of contents
Page 1
... C4 330µ IRLZ44 OUT3 1.5V C6 R1, 0 330µF R2, 50k Note: All surface-mount packages are available in Tape & Reel, append the letter "T" to part number. (i.e. LX1668CPWT Copyright © 1999 11861 W A Rev. 1.0 4/99 ESTERN P ROGRAMMABLE Internal Low Dropout [LDO] Regulator provides a fixed 2 ...
Page 2
... LX1668 P ROGRAMMABLE LUT E MAXIM UM RAT INGS 12V Supply Voltage (V ) .................................................................................. 18V CC12 5V Supply Voltage (V ) ....................................................................................... 7V CC5 Supply Voltage (Internal LDO)/(V CC3 Output Drive Peak Current Source (500ns) ....................................................... 1.0A Output Drive Peak Current Sink (500ns) ........................................................... 1.0A Input Voltage (SS, VID[0:4]) ................................................................... -0. Operating Junction Temperature .................................................................... 150° ...
Page 3
... LFB OUT I I flows from V LDRV LDRV CC12 I LDRV V Internally pulled thru 30k IL CC5 V IH LX1668 ONTROLLER 5V, V CC3 CC5 CC5 CC12 LX1668 Min. Typ. Max 35V 25°C CORE -1.5 1.5 2.4 250 -0.3 -1 100 100 100 10 11 0.1 3.9 4.2 4.6 ...
Page 4
... LX1668 P ROGRAMMABLE Table 1 - Adaptive Transient Voltage Output VID4 Nominal = DAC setpoint voltage with no adaptive output voltage positioning. ...
Page 5
... RESET Set 40mV V RESET Error Comp R SS 20k Off-Time Hiccup Control Hiccup C SS FIGURE 3 — Block Diagram LX1668 ONTROLLER EFFICIE NCY A T 3.1V EFFICIE NCY A T 2.8V EFFICIE NCY (A) OUT FIGURE 2 — Efficiency Test Results: ...
Page 6
... LX1668 P ROGRAMMABLE Pin Pin Number Designator Description 1 TDRV Gate drive to the top FET +12V supply for the gate drivers. If 12V is not available in the application, a bootstrap circuit is required CC12 to create the biasing voltage for the FET gate drivers. ...
Page 7
... POWER UP and INITIALIZATION At power up, the LX1668 monitors the supply voltage to both the +5V and the +12V pins (there is no special requirement for the sequence of the two supplies). Before both supplies reach their ...
Page 8
... LX1668 P ROGRAMMABLE OVER-CURRENT PROTECTION (OCP) and HICCUP The over-current protection function is tripped when the induc- tor current exceeds its maximum limit. The current is sensed with a resistor in series with the inductor. When the voltage ...
Page 9
... M O DC: LTIPLE UTPUT LX1668 Bill of Materials (Refer to Product Highlight) Part Number / Manufacturer LX1668 - LinFinity MV-GX Sanyo MV-GX Sanyo MV-GX Sanyo MV-GX Sanyo ) IRL3102/3103, International Rectifier ) IRL3303/3103, International Rectifier IRLZ44N, International Rectifier ...
Page 10
... LX1668 P ROGRAMMABLE L = 5µH, L OUT OUTPUT INDUCTOR The output inductor should be selected to meet the requirements of the output voltage ripple in steady-state operation and the inductor current slew-rate during transient. The peak-to-peak output voltage ripple is: ...
Page 11
... V , allowing a higher ESR value and EX reducing the cost of the output capacitor. positioning voltage is 40mV (peak), using the LX1668, and the transient tolerance is 100mV, resulting Figure 4). Electrolytic capacitors can be used for the output capacitor, but are less stable with age than tantalum capacitors. As they age, their ESR degrades, reducing the system performance and increasing the risk of failure ...
Page 12
... LX1668 P ROGRAMMABLE CURRENT LIMIT (continued) There are several alternative types of sense resistor. The surface-mount metal “staple” form of resistor has the advantage of exposure to free air to dissipate heat and its value can be controlled very tightly ...
Page 13
... S2 S more information. OUTPUT ENABLE The LX1668 FET driver outputs are driven to ground by pulling the soft-start pin below 0.5V. PROGRAMMING THE OUTPUT VOLTAGE The output voltage is set by the DAC with a 5-bit digital voltage- identification (VID) code input (see Table 1). The DAC input is designed to be compatible with digital circuits ...
Page 14
... OUT2 V can be connected 3.3V, but 5V is recommended for CC3 optimal performance. Adjustable External LDO Regulator The LX1668 has a linear regulator driver function. A low dropout linear regulator can be constructed by connecting an external MOSFET to the L and L pins. The MOSFET can provide an DRV FB output with a minimum voltage of 1 ...
Page 15
... A Gerber file with layout for the most popular devices is available upon request. Evaluation boards are also available upon request. Please check Linfinity's web site for further application notes. Pentium is a registered trademark of Intel Corporation. LX1668 ONTROLLER (continued) 5V Input 3 ...