Datasheet LTC7878 (Analog Devices) - 9
| Manufacturer | Analog Devices |
| Description | 70V Parallelable 4-Switch Buck-Boost Controller with Inductor DCR Current Sensing |
| Pages / Page | 30 / 9 — PIN FUNCTIONS (QFN/LFCSP) PHASMD (Pin 18/Pin 27):. CSP, CSN (Pins 23, … |
| File Format / Size | PDF / 2.4 Mb |
| Document Language | English |
PIN FUNCTIONS (QFN/LFCSP) PHASMD (Pin 18/Pin 27):. CSP, CSN (Pins 23, 24/Pins 34, 35):. OUT (Pin 25/Pin 38):
Model Line for this Datasheet
Text Version of Document
link to page 15 link to page 15 LTC7878
PIN FUNCTIONS (QFN/LFCSP) PHASMD (Pin 18/Pin 27):
Phase Mode Program Pin. This
CSP, CSN (Pins 23, 24/Pins 34, 35):
Average Current pin sets the phase relationship between the internal oscil- Sensing Pins. The positive/negative inputs of the internal lator clock and the output clock on the CLKOUT pin. Tie rail-to-rail average current sense amplifier. this pin to SGND sets 180-degree phase-shift, float this
V
pin sets 120-degree phase-shift and tie this pin to INTV
OUT (Pin 25/Pin 38):
Floating Driver Bias Pin in Boost CC Mode. Supply the bias current for the BOOST1 to SW1 sets 90-degree phase-shift. See Applications Information driver circuitry when V section for details. OUT is much higher than VIN.
NC (Pin 26/Pins 2, 3, 5, 6, 13, 17, 18, 23, 24, 32, 33, FREQ (Pin 19/Pin 28):
Frequency Set Pin. A resistor
36, 37, 39, 40, 44, 48):
No Connect Pin. between this pin and SGND sets the switching frequency. This pin sources 10µA current.
ISNSN (Pin 27/Pin 41):
Negative Current Sense Comparator Inputs. The negative input of the current
CLKOUT (Pin 20/Pin 29):
Clock Output Pin. Use this pin to comparator is normal y connected to the DCR sensing synchronize the switching frequency of multiple LTC7878 network. ICs for parallel operations. Signal swings is from INTVCC to ground.
ISNSP (Pin 28/Pin 42):
Positive Current Sense Comparator Inputs. This pin must be Kelvin connected to the inductor
SYNC (Pin 21/Pin 30):
Switching Frequency on the switching node SW1. Synchronization Pin. Applying an external clock between 100kHz to 600kHz will cause the switching frequency to
ISNSD (Pin 29/Pin 43):
DC Current Sense Comparator synchronize to the external clock. If SYNC is low, a resis- Inputs. These inputs amplify the DC portion of the sensed tor from the FREQ pin to SGND sets the default switching current signal to the IC’s current comparator. If no use frequency. This pin has a 500k internal resistor to ground. in large DCR applications, short ISNSD pin to ISNSP pin locally. See Applications Information section for details.
SETCUR (Pin 22/Pin 31):
Average Current Regulation Pin. A resistor from this pin to SGND sets the maximum
SGND (Exposed Pad Pin 33/Pin 49):
Signal Ground Pin. average input or output current sensed by the CSP and Must be soldered to PCB ground for rated thermal per- CSN pins. This pin sources 15μA current. formance. All small signal components e.g., INTVCC, SS, ITH, VFB, FREQ, etc. should be connected here. Rev. C For more information www.analog.com 9 Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Order Information Pin Configuration Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Typical Applications Package Description Typical Application Related Parts
PIN FUNCTIONS (QFN/LFCSP) PHASMD (Pin 18/Pin 27):
Phase Mode Program Pin. This
CSP, CSN (Pins 23, 24/Pins 34, 35):
Average Current pin sets the phase relationship between the internal oscil- Sensing Pins. The positive/negative inputs of the internal lator clock and the output clock on the CLKOUT pin. Tie rail-to-rail average current sense amplifier. this pin to SGND sets 180-degree phase-shift, float this
V
pin sets 120-degree phase-shift and tie this pin to INTV
OUT (Pin 25/Pin 38):
Floating Driver Bias Pin in Boost CC Mode. Supply the bias current for the BOOST1 to SW1 sets 90-degree phase-shift. See Applications Information driver circuitry when V section for details. OUT is much higher than VIN.
NC (Pin 26/Pins 2, 3, 5, 6, 13, 17, 18, 23, 24, 32, 33, FREQ (Pin 19/Pin 28):
Frequency Set Pin. A resistor
36, 37, 39, 40, 44, 48):
No Connect Pin. between this pin and SGND sets the switching frequency. This pin sources 10µA current.
ISNSN (Pin 27/Pin 41):
Negative Current Sense Comparator Inputs. The negative input of the current
CLKOUT (Pin 20/Pin 29):
Clock Output Pin. Use this pin to comparator is normal y connected to the DCR sensing synchronize the switching frequency of multiple LTC7878 network. ICs for parallel operations. Signal swings is from INTVCC to ground.
ISNSP (Pin 28/Pin 42):
Positive Current Sense Comparator Inputs. This pin must be Kelvin connected to the inductor
SYNC (Pin 21/Pin 30):
Switching Frequency on the switching node SW1. Synchronization Pin. Applying an external clock between 100kHz to 600kHz will cause the switching frequency to
ISNSD (Pin 29/Pin 43):
DC Current Sense Comparator synchronize to the external clock. If SYNC is low, a resis- Inputs. These inputs amplify the DC portion of the sensed tor from the FREQ pin to SGND sets the default switching current signal to the IC’s current comparator. If no use frequency. This pin has a 500k internal resistor to ground. in large DCR applications, short ISNSD pin to ISNSP pin locally. See Applications Information section for details.
SETCUR (Pin 22/Pin 31):
Average Current Regulation Pin. A resistor from this pin to SGND sets the maximum
SGND (Exposed Pad Pin 33/Pin 49):
Signal Ground Pin. average input or output current sensed by the CSP and Must be soldered to PCB ground for rated thermal per- CSN pins. This pin sources 15μA current. formance. All small signal components e.g., INTVCC, SS, ITH, VFB, FREQ, etc. should be connected here. Rev. C For more information www.analog.com 9 Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Order Information Pin Configuration Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Typical Applications Package Description Typical Application Related Parts