Datasheet LTC3613 (Analog Devices) - 8
| Manufacturer | Analog Devices |
| Description | 24V, 15A Monolithic Step Down Regulator with Differential Output Sensing |
| Pages / Page | 36 / 8 — PIN FUNCTIONS. PVIN (Pins 1-9, 53-56, 57 Exposed Pad):. VOUT (Pin 18):. … |
| File Format / Size | PDF / 464 Kb |
| Document Language | English |
PIN FUNCTIONS. PVIN (Pins 1-9, 53-56, 57 Exposed Pad):. VOUT (Pin 18):. OSNS (Pin 20):
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Text Version of Document
LTC3613
PIN FUNCTIONS PVIN (Pins 1-9, 53-56, 57 Exposed Pad):
Power Supply
VOUT (Pin 18):
Output voltage sense for adjusting the Inputs. These pins connect to the drain of the internal on-time for constant frequency operation. Tying this pin to power MOSFETS. The PVIN exposed pad must be soldered the local output (instead of the remote output) is recom- to the circuit board for electrical contact and rated thermal mended for most applications. This pin can be programmed performance. The supply voltage can range from 4.5V to as needed for achieving the steady-state on-time required 24V. The voltage on this pin is also used to adjust the TG for constant frequency operation. on-time in order to maintain constant frequency operation.
V – OSNS (Pin 20):
Differential Output Sensing (–) Input.
SW (Pins 10, 35, 45-51, 58 Exposed Pad):
Switch Node Connect this pin to the negative terminal of the output Connection. The (–) terminal of the bootstrap capacitor, capacitor. There is a bias current of 35μA (typical) flowing CB, connects to this node. This pin swings from a diode out of this pin. voltage below ground up to VIN. The SW exposed pad must
V + (Pin 21):
Differential Output Sensing (+) Input. be soldered to the circuit board for electrical contact and
OSNS
Connect this pin to the feedback resistor divider between rated thermal performance. the positive and negative output capacitor terminals. In
BOOST (Pin 11):
Boosted Driver Supply Connection. The normal operation the LTC3613 will regulate the differen- (+) terminal of the bootstrap capacitor, CB, as well as tial output voltage which is divided down to 0.6V by the the cathode of the Schottky diode, DB, connects to this feedback resistor divider. node. This node swings from INTVCC – VSCHOTTKY to VIN
TRACK/SS (Pin 22):
External Tracking and Soft-Start Input. + INTVCC – VSCHOTTKY. The LTC3613 regulates the differential feedback voltage
SGND (Pins 12, 16, 17, 19, 28, 29, 59 Exposed Pad):
(V + – OSNS − VOSNS ) to the smaller of 0.6V or the voltage Signal Ground Connection. The SGND exposed pad must on the TRACK/SS pin. An internal 1.0μA pull-up current be soldered to the circuit board for electrical contact and source is connected to this pin. A capacitor to ground at rated thermal performance. All small-signal components this pin sets the ramp time to the final regulated output should be connected to the signal ground. Connect signal voltage. Alternatively, another voltage supply connected ground to power ground only at one point using a single through a resistor divider to this pin allows the output to PCB trace. track the other supply during start-up.
PGOOD (Pin 13):
Power Good Indicator Output. This
ITH (Pin 23):
Current Control Voltage and Switching Regu- open-drain logic output is pulled to ground when the lator Compensation Point. The current sense threshold output voltage is outside of a ±7.5% window around the increases with this control voltage which ranges from regulation point. 0V to 2.4V.
SENSE+ (Pin 14):
Differential Current Sensing (+) Input.
VRNG (Pin 24):
Current Sense Voltage Range Input. The For RSENSE current sensing, Kelvin (4-wire) connect maximum allowed sense voltage between SENSE+ and SENSE+ and SENSE– pins across the sense resistor. For SENSE– is equal to 0.05 • VRNG. If VRNG is tied to SGND, DCR sensing, Kelvin connect SENSE+ and SENSE– pins the device operates with a maximum sense voltage of across the sense filter capacitor. 30mV. If VRNG is tied to INTVCC, the device operates with a maximum sense voltage of 50mV.
SENSE– (Pin 15):
Differential Current Sensing (–) Input. For RSENSE current sensing, Kelvin (4-wire) connect the
RT (Pin 25):
Switching Frequency Programming Pin. SENSE+ and SENSE– pins across the sense resistor. For Connect an external resistor from RT to signal ground to DCR sensing, Kelvin connect the SENSE+ and SENSE– pins program the switching frequency between 200kHz and across the sense filter capacitor. 1MHz. An external clock applied to MODE/PLLIN must be within ±30% of this free-running frequency to ensure frequency lock. 3613fa 8
PIN FUNCTIONS PVIN (Pins 1-9, 53-56, 57 Exposed Pad):
Power Supply
VOUT (Pin 18):
Output voltage sense for adjusting the Inputs. These pins connect to the drain of the internal on-time for constant frequency operation. Tying this pin to power MOSFETS. The PVIN exposed pad must be soldered the local output (instead of the remote output) is recom- to the circuit board for electrical contact and rated thermal mended for most applications. This pin can be programmed performance. The supply voltage can range from 4.5V to as needed for achieving the steady-state on-time required 24V. The voltage on this pin is also used to adjust the TG for constant frequency operation. on-time in order to maintain constant frequency operation.
V – OSNS (Pin 20):
Differential Output Sensing (–) Input.
SW (Pins 10, 35, 45-51, 58 Exposed Pad):
Switch Node Connect this pin to the negative terminal of the output Connection. The (–) terminal of the bootstrap capacitor, capacitor. There is a bias current of 35μA (typical) flowing CB, connects to this node. This pin swings from a diode out of this pin. voltage below ground up to VIN. The SW exposed pad must
V + (Pin 21):
Differential Output Sensing (+) Input. be soldered to the circuit board for electrical contact and
OSNS
Connect this pin to the feedback resistor divider between rated thermal performance. the positive and negative output capacitor terminals. In
BOOST (Pin 11):
Boosted Driver Supply Connection. The normal operation the LTC3613 will regulate the differen- (+) terminal of the bootstrap capacitor, CB, as well as tial output voltage which is divided down to 0.6V by the the cathode of the Schottky diode, DB, connects to this feedback resistor divider. node. This node swings from INTVCC – VSCHOTTKY to VIN
TRACK/SS (Pin 22):
External Tracking and Soft-Start Input. + INTVCC – VSCHOTTKY. The LTC3613 regulates the differential feedback voltage
SGND (Pins 12, 16, 17, 19, 28, 29, 59 Exposed Pad):
(V + – OSNS − VOSNS ) to the smaller of 0.6V or the voltage Signal Ground Connection. The SGND exposed pad must on the TRACK/SS pin. An internal 1.0μA pull-up current be soldered to the circuit board for electrical contact and source is connected to this pin. A capacitor to ground at rated thermal performance. All small-signal components this pin sets the ramp time to the final regulated output should be connected to the signal ground. Connect signal voltage. Alternatively, another voltage supply connected ground to power ground only at one point using a single through a resistor divider to this pin allows the output to PCB trace. track the other supply during start-up.
PGOOD (Pin 13):
Power Good Indicator Output. This
ITH (Pin 23):
Current Control Voltage and Switching Regu- open-drain logic output is pulled to ground when the lator Compensation Point. The current sense threshold output voltage is outside of a ±7.5% window around the increases with this control voltage which ranges from regulation point. 0V to 2.4V.
SENSE+ (Pin 14):
Differential Current Sensing (+) Input.
VRNG (Pin 24):
Current Sense Voltage Range Input. The For RSENSE current sensing, Kelvin (4-wire) connect maximum allowed sense voltage between SENSE+ and SENSE+ and SENSE– pins across the sense resistor. For SENSE– is equal to 0.05 • VRNG. If VRNG is tied to SGND, DCR sensing, Kelvin connect SENSE+ and SENSE– pins the device operates with a maximum sense voltage of across the sense filter capacitor. 30mV. If VRNG is tied to INTVCC, the device operates with a maximum sense voltage of 50mV.
SENSE– (Pin 15):
Differential Current Sensing (–) Input. For RSENSE current sensing, Kelvin (4-wire) connect the
RT (Pin 25):
Switching Frequency Programming Pin. SENSE+ and SENSE– pins across the sense resistor. For Connect an external resistor from RT to signal ground to DCR sensing, Kelvin connect the SENSE+ and SENSE– pins program the switching frequency between 200kHz and across the sense filter capacitor. 1MHz. An external clock applied to MODE/PLLIN must be within ±30% of this free-running frequency to ensure frequency lock. 3613fa 8
