The LM5009 step-down switching regulator features all of the functions needed to implement a low-cost and efficient, buck regulator. This device is capable of driving a 150-mA load current from a 9.5-V to 95-V input source. The switching frequency can exceed 600 kHz, depending on the input and output voltages. The output voltage can be set from 2.5 V to 85 V. This high-voltage regulator contains an N-channel buck switch and an internal startup regulator. The device is easy to implement and is provided in 8-pin VSSOP and thermally-enhanced, 8-pin WSON packages. The regulator operation is based on a control scheme using an on-time inversely proportional to VIN. This feature allows the operating frequency to remain relatively constant over load and input voltage variations. The control scheme requires no loop compensation, resulting in an ultrafast transient response. An intelligent current limit is implemented with forced off-time that is inversely proportional to VOUT. This scheme ensures short-circuit protection and provides minimum foldback. Other features include thermal shutdown, VCC undervoltage lockout, gate drive undervoltage lockout, and maximum duty cycle limiter.
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PART NUMBER | PACKAGE | BODY SIZE (NOM) |
---|---|---|
LM5009 | VSSOP (8) | 3.00 mm × 3.00 mm |
WSON (8) | 4.00 mm × 4.00 mm |
Changes from Revision H (October 2015) to Revision I (May 2021)
Changes from Revision G (February 2013) to Revision H (October 2015)
Changes from Revision F (February 2013) to Revision G (February 2013)
PIN | I/O | DESCRIPTION | |
---|---|---|---|
NAME | NO. | ||
BST | 2 | I | Boost pin. An external capacitor is required between the BST and SW pins. A 0.022-µF ceramic capacitor is recommended. An internal diode charges the capacitor from VCC. |
EP | — | — | Exposed pad (WSON package only). Exposed metal pad on the underside of the device. Connecting this pad to the PC board ground plane is recommended to aid in heat dissipation. |
FB | 5 | I | Feedback input from regulated output. This pin is connected to the inverting input of the internal regulation comparator. The regulation threshold is 2.5 V. |
RCL | 3 | I | Current limit off-time set pin. A resistor between this pin and RTN sets the off-time when current limit is detected. The off-time is preset to 35 µs if FB = 0 V. |
RON/SD | 6 | I | On-time set pin. A resistor between this pin and VIN sets the switch on-time as a function of VIN. The minimum recommended on-time is 250 ns at the maximum input voltage. This pin can be used for remote shutdown. |
RTN | 4 | — | Ground pin. Ground for the entire circuit. |
SW | 1 | O | Switching output. Power switching output. Connect to the inductor, recirculating diode, and bootstrap capacitor. |
VCC | 7 | O | Output from the internal high-voltage startup regulator. Regulated at 7.0 V. If an auxiliary voltage is available to raise the voltage on this pin above the regulation set point (7 V), the internal series pass regulator shuts down, reducing the device power dissipation. Do not exceed 14 V. This voltage provides gate drive power for the internal buck switch. An internal diode is provided between this pin and the BST pin. A local 0.1-µF decoupling capacitor is required. |
VIN | 8 | I | Input voltage. Recommended operating range: 9.5 V to 95 V. |
MIN | MAX | UNIT | |
---|---|---|---|
VIN to RTN | –0.3 | 100 | V |
BST to RTN | –0.3 | 114 | V |
SW to RTN (steady-state) | –1 | V | |
BST to VCC | 100 | V | |
BST to SW | 14 | V | |
VCC to RTN | 14 | V | |
All other inputs to RTN | –0.3 | 7 | V |
Storage temperature, Tstg | –65 | 150 | °C |