Datasheet LT8390A (Analog Devices) - 10
| Manufacturer | Analog Devices |
| Description | 60V 2MHz Synchronous 4-Switch Buck-Boost Controller with Spread Spectrum |
| Pages / Page | 30 / 10 — PIN FUNCTIONS CTRL:. VC:. RT:. SYNC/SPRD:. ISP:. ISN:. LOADTG:. ISMON:. … |
| File Format / Size | PDF / 1.1 Mb |
| Document Language | English |
PIN FUNCTIONS CTRL:. VC:. RT:. SYNC/SPRD:. ISP:. ISN:. LOADTG:. ISMON:. VOUT:. PGOOD:. TG2:. SS:. SW2:. BST2:. BG2:. FB:. GND (Exposed Pad):
Model Line for this Datasheet
Text Version of Document
LT8390A
PIN FUNCTIONS CTRL:
Control Input for ISP/ISN Current Sense Threshold. short-circuit (VFB < 0.25V) condition, the part gets into one The CTRL pin is used to program the ISP/ISN current limit: fault mode per customer setting. During an overvoltage (V Min(V ) FB > 1.1V) condition, the part turns off all TG1, BG1, I CTRL − 0.25V,1V TG2, BG2, and LOADTG. IS(MAX) =
10 •RIS
VC:
Error Amplifier Output to Set Inductor Current Com- The V parator Threshold. The V CTRL can be set by an external voltage reference or C pin is used to compensate the a resistor divider from V control loop with an external RC network. During LOADEN REF to ground. For 0.3V ≤ VCTRL ≤ 1.15V, the current sense threshold linearly goes up low state, the VC pin is disconnected from all internal loads from 5mV to 90mV. For V to store its voltage information. CTRL ≥ 1.35V, the current sense threshold is constant at 100mV full scale value. For 1.15V
RT:
Switching Frequency Setting. Connect a resistor from ≤ VCTRL ≤ 1.35V, the current sense threshold smoothly this pin to ground to set the internal oscillator frequency transitions from the linear function of VCTRL to the 100mV from 600kHz to 2MHz. constant value. Tie CTRL to VREF for the 100mV full scale threshold. Force the pin below 0.3V to stop switching.
SYNC/SPRD:
Switching Frequency Synchronization or Spread Spectrum. Ground this pin for switching at inter-
ISP:
Positive Terminal of the ISP/ISN Current Sense Re- nal oscillator frequency. Apply a clock signal for external sistor (RIS). Ensure accurate current sense with Kelvin frequency synchronization. Tie to INTVCC for 25% triangle connection. spread spectrum above internal oscillator frequency.
ISN:
Negative Terminal of the ISP/ISN Current Sense
LOADTG:
High Side PMOS Load Switch Top Gate Drive. A Resistor (RIS). Ensure accurate current sense with Kelvin buffered and inverted version of the LOADEN input signal, the connection. LOADTG pin drives an external high side PMOS load switch
ISMON:
ISP/ISN Current Sense Monitor Output. The ISMON with a voltage swing from the higher voltage of (VOUT-5V) pin generates a voltage that is equal to ten times V and 1.2V to V (ISP-ISN) OUT. Leave this pin unconnected if not used. plus 0.25V offset voltage. For parallel applications, tie the
VOUT:
Output Supply. The VOUT pin must be tied to the master LT8390A ISMON pin to the slave LT8390A CTRL pin. power output to determine the buck, buck-boost, or boost
PGOOD:
Power Good Open Drain Output. The PGOOD operation regions. The VOUT pin also serves as positive rail pin is pulled low when the FB pin is within ±10% of the for the LOADTG drive. Locally bypass this pin to ground final regulation voltage. To function, the pin requires an with a minimum 1µF ceramic capacitor. external pull-up resistor.
TG2:
Boost Side Top Gate Drive. Drives the gate of boost
SS:
Soft-Start Timer Setting. The SS pin is used to set side top N-Channel MOSFET with a voltage swing from soft-start timer by connecting a capacitor to ground. An SW2 to BST2. internal 12.5µA pull-up current charging the external SS
SW2:
Boost Side Switch Node. The SW2 pin swings from capacitor gradually ramps up FB regulation voltage. A a Schottky diode voltage drop below ground to VOUT. 22nF capacitor is recommended on this pin. Any UVLO or thermal shutdown immediately pulls SS pin to ground and
BST2:
Boost Side Bootstrap Floating Driver Supply. The stops switching. Using a single resistor from SS to V BST2 pin has an integrated bootstrap Schottky diode from REF, the LT8390A can be set in three different fault protection the INTVCC pin and requires an external bootstrap capacitor modes during output short-circuit condition: hiccup (no to the SW2 pin. The BST2 pin swings from a diode voltage resistor), latch-off (499kΩ), and keep-running (100kΩ). drop below INTVCC to (VOUT + INTVCC). See more details in the Application Information section.
BG2:
Boost Side Bottom Gate Drive. Drives the gate of
FB:
Voltage Loop Feedback Input. The FB pin is used for boost side bottom N-channel MOSFET with a voltage constant-voltage regulation and output fault protection. swing from ground to INTVCC. The internal error amplifier with its output VC regulates
GND (Exposed Pad):
Ground. Solder the exposed pad VFB to 1.00V through the DC/DC converter. During output directly to the ground plane. 8390afa 10 For more information www.linear.com/LT8390A Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Typical Applications Package Description Typical Application Related Parts
PIN FUNCTIONS CTRL:
Control Input for ISP/ISN Current Sense Threshold. short-circuit (VFB < 0.25V) condition, the part gets into one The CTRL pin is used to program the ISP/ISN current limit: fault mode per customer setting. During an overvoltage (V Min(V ) FB > 1.1V) condition, the part turns off all TG1, BG1, I CTRL − 0.25V,1V TG2, BG2, and LOADTG. IS(MAX) =
10 •RIS
VC:
Error Amplifier Output to Set Inductor Current Com- The V parator Threshold. The V CTRL can be set by an external voltage reference or C pin is used to compensate the a resistor divider from V control loop with an external RC network. During LOADEN REF to ground. For 0.3V ≤ VCTRL ≤ 1.15V, the current sense threshold linearly goes up low state, the VC pin is disconnected from all internal loads from 5mV to 90mV. For V to store its voltage information. CTRL ≥ 1.35V, the current sense threshold is constant at 100mV full scale value. For 1.15V
RT:
Switching Frequency Setting. Connect a resistor from ≤ VCTRL ≤ 1.35V, the current sense threshold smoothly this pin to ground to set the internal oscillator frequency transitions from the linear function of VCTRL to the 100mV from 600kHz to 2MHz. constant value. Tie CTRL to VREF for the 100mV full scale threshold. Force the pin below 0.3V to stop switching.
SYNC/SPRD:
Switching Frequency Synchronization or Spread Spectrum. Ground this pin for switching at inter-
ISP:
Positive Terminal of the ISP/ISN Current Sense Re- nal oscillator frequency. Apply a clock signal for external sistor (RIS). Ensure accurate current sense with Kelvin frequency synchronization. Tie to INTVCC for 25% triangle connection. spread spectrum above internal oscillator frequency.
ISN:
Negative Terminal of the ISP/ISN Current Sense
LOADTG:
High Side PMOS Load Switch Top Gate Drive. A Resistor (RIS). Ensure accurate current sense with Kelvin buffered and inverted version of the LOADEN input signal, the connection. LOADTG pin drives an external high side PMOS load switch
ISMON:
ISP/ISN Current Sense Monitor Output. The ISMON with a voltage swing from the higher voltage of (VOUT-5V) pin generates a voltage that is equal to ten times V and 1.2V to V (ISP-ISN) OUT. Leave this pin unconnected if not used. plus 0.25V offset voltage. For parallel applications, tie the
VOUT:
Output Supply. The VOUT pin must be tied to the master LT8390A ISMON pin to the slave LT8390A CTRL pin. power output to determine the buck, buck-boost, or boost
PGOOD:
Power Good Open Drain Output. The PGOOD operation regions. The VOUT pin also serves as positive rail pin is pulled low when the FB pin is within ±10% of the for the LOADTG drive. Locally bypass this pin to ground final regulation voltage. To function, the pin requires an with a minimum 1µF ceramic capacitor. external pull-up resistor.
TG2:
Boost Side Top Gate Drive. Drives the gate of boost
SS:
Soft-Start Timer Setting. The SS pin is used to set side top N-Channel MOSFET with a voltage swing from soft-start timer by connecting a capacitor to ground. An SW2 to BST2. internal 12.5µA pull-up current charging the external SS
SW2:
Boost Side Switch Node. The SW2 pin swings from capacitor gradually ramps up FB regulation voltage. A a Schottky diode voltage drop below ground to VOUT. 22nF capacitor is recommended on this pin. Any UVLO or thermal shutdown immediately pulls SS pin to ground and
BST2:
Boost Side Bootstrap Floating Driver Supply. The stops switching. Using a single resistor from SS to V BST2 pin has an integrated bootstrap Schottky diode from REF, the LT8390A can be set in three different fault protection the INTVCC pin and requires an external bootstrap capacitor modes during output short-circuit condition: hiccup (no to the SW2 pin. The BST2 pin swings from a diode voltage resistor), latch-off (499kΩ), and keep-running (100kΩ). drop below INTVCC to (VOUT + INTVCC). See more details in the Application Information section.
BG2:
Boost Side Bottom Gate Drive. Drives the gate of
FB:
Voltage Loop Feedback Input. The FB pin is used for boost side bottom N-channel MOSFET with a voltage constant-voltage regulation and output fault protection. swing from ground to INTVCC. The internal error amplifier with its output VC regulates
GND (Exposed Pad):
Ground. Solder the exposed pad VFB to 1.00V through the DC/DC converter. During output directly to the ground plane. 8390afa 10 For more information www.linear.com/LT8390A Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Typical Applications Package Description Typical Application Related Parts
