LM2645MTD National Semiconductor, LM2645MTD Datasheet
LM2645MTD
Available stocks
Related parts for LM2645MTD
LM2645MTD Summary of contents
Page 1
... The switching outputs have under-voltage and over-voltage latch protection, while the output of the external linear regulator has undervoltage latch protection. The undervoltage latch can be disabled or adjustably de- layed. © 2005 National Semiconductor Corporation Features GENERAL n 4.5V to 30V input range n Power good function n Input under-voltage lockout n 10 µ ...
Page 2
... Connection Diagram TOP VIEW 48-Lead TSSOP (MTD) Order Number LM2645MTD See NS Package Number MTD48 Pin Descriptions VO1 (Pin 1):The feedback input for Channel 1. Always con- nect directly to the output. Fixed or adjustable output voltage is selected by FB1_FIX. FB1_FIX (Pin 2): The feedback input for setting the output voltage of Channel 1 ...
Page 3
Pin Descriptions (Continued) of the top MOSFET or the voltage across an external current sense resistor to determine if an over-current condition has occurred in Channel 2. RSNS2 (Pin 26): The negative (−) Kelvin sense for the internal current limit ...
Page 4
www.national.com 4 ...
Page 5
5 www.national.com ...
Page 6
www.national.com 6 ...
Page 7
Notes: 1. "fault" is the logic OR of UVLO and thermal shutdown. 2. "cap" means the pin has a capacitor of appropriate value between it and ground. 3. ...
Page 8
... Absolute Maximum Ratings If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Voltages from the indicated pins to SGND/PGND: VIN, ILIM1, ILIM2, KS1, KS2, LDODRV SW1, SW2, RSNS1, RSNS2 VO1, VO2, FB1_FIX, FB2_FIX, VDD1, VDD2, EXT ...
Page 9
Electrical Characteristics Unless otherwise specified 15V, SGND = PGND = 0V, VLIN5 = VDD1 = VDD2. Limits appearing in boldface type apply IN over the entire operating junction temperature range, 0˚C to +125˚C. Specifications appearing in plain type ...
Page 10
Electrical Characteristics Unless otherwise specified 15V, SGND = PGND = 0V, VLIN5 = VDD1 = VDD2. Limits appearing in boldface type apply IN over the entire operating junction temperature range, 0˚C to +125˚C. Specifications appearing in plain type ...
Page 11
... Note 3: For detailed information on soldering plastic small-outline packages, refer to the Packaging Databook available from National Semiconductor Corporation. Note 4: Except for SW1, SW2, CBOOT1 and CBOOT2 pins which are 1.5kV. For testing purposes, ESD was applied using the human-body model, a 100pF capacitor discharged through a 1.5kΩ ...
Page 12
Typical Performance Characteristics Efficiency vs Load Current (FPWM/2NDFB = VLIN5) Efficiency vs Load Current (FPWM/2NDFB = VLIN5) Reference Voltage vs Temperature (Bandgap + Error Amplifier Offset) www.national.com Efficiency vs Load Current (FPWM/2NDFB = VLIN5) 20015906 Quiescent Current vs Supply Voltage ...
Page 13
Typical Performance Characteristics Switching Frequency vs Load Current (FPWM/2NDFB = VLIN5) VLIN5 Output vs Temperature Shutdown Waveforms (V = 3.3V 0A) OUT OUT (Continued) Normalized Switching Frequency vs Temperature 20015909 (V = 15V, EXT = Vo1 = 5V, ...
Page 14
Typical Performance Characteristics Load Transient Response (V = 10V 3.3V 6.0 µ OUT Overcurrent and Undervoltage Protection (V = 5V, V OUT1 OUT2 Soft Start (V = 10V to 28V 5V, I ...
Page 15
Operation Descriptions GENERAL The LM2645 integrates two synchronous switching control- lers, one adjustable linear regulator controller and one fixed 3.3V output into a single package. It solves the need within many portable systems for 5V, 3.3V, 3.3V stand-by and 12V ...
Page 16
Operation Descriptions The force-PWM mode is good for applications where fixed switching frequency is required. In force-PWM mode, the top FET has to be turned on for a minimum of typically 220ns each cycle. However, when the required duty cycle ...
Page 17
Operation Descriptions NEGATIVE CURRENT LIMIT The purpose of negative current limit is to ensure that the inductor will not saturate during negative current flow caus- ing excessive current to flow through the bottom FET. The negative current limit is realized ...
Page 18
Operation Descriptions FIGURE 3. Connecting OUT3 to VLIN5 when not in use Likewise, if the LDODRV pin is not used, connect the LD- OFB pin to VLIN5 as shown in Figure 4 to disable this channel and the under voltage ...
Page 19
Operation Descriptions (Continued) FIGURE 7. Dual-Phase parallel operation 19 20015904 www.national.com ...
Page 20
... Deutsch Tel: +49 (0) 69 9508 6208 English www.national.com Français Tel: +33 ( 8790 48-Lead TSSOP Package Order Number LM2645MTD NS Package Number MTD48 2. A critical component is any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system affect its safety or effectiveness ...