Datasheet LTC3129 (Analog Devices) - 8
| Hersteller | Analog Devices |
| Beschreibung | 15V, 200mA Synchronous Buck-Boost DC/DC Converter with 1.3μA Quiescent Current |
| Seiten / Seite | 30 / 8 — pin FuncTions (QFN/MSOP). BST1 (Pin 1/Pin 15):. NC (Pins 8, 9/Pins 6, … |
| Dateiformat / Größe | PDF / 1.6 Mb |
| Dokumentensprache | Englisch |
pin FuncTions (QFN/MSOP). BST1 (Pin 1/Pin 15):. NC (Pins 8, 9/Pins 6, 7):. VIN (Pin 2/Pin 16):. PWM (Pin 10/Pin 8):
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LTC3129
pin FuncTions (QFN/MSOP) BST1 (Pin 1/Pin 15):
Bootstrapped Floating Supply for VOUT = 1.175V • [1+(R1/R2)]. Note this pin is very noise High Side NMOS Gate Drive. Connect to SW1 through a sensitive, therefore minimize trace length and stray ca- 22nF capacitor, as close to the part as possible. The value pacitance. is not critical. Any value from 4.7nF to 47nF may be used.
NC (Pins 8, 9/Pins 6, 7):
Unused. These pins should be
VIN (Pin 2/Pin 16):
Input Voltage for the Converter. Connect grounded. a minimum of 4.7µF ceramic decoupling capacitor from
PWM (Pin 10/Pin 8):
Mode Select Pin. this pin to the ground plane, as close to the pin as possible. PWM = Low (ground): Enables automatic Burst Mode
VCC (Pin 3/Pin 1):
Output voltage of the internal voltage operation. regulator. This is the supply pin for the internal circuitry. Bypass this output with a minimum of 2.2µF ceramic PWM = High (tie to VCC): Fixed frequency PMW opera- capacitor close to the pin. This pin may be back-driven by tion. an external supply, up to a maximum of 5.5V. This pin should not be allowed to float. It has an internal
RUN (Pin 4/Pin 2):
Input to the Run Comparator. Pull 5M pull-down resistor. this pin above 1.1V to enable the VCC regulator and above
PGOOD (Pin 11/Pin 9):
Open drain output that pulls to 1.28V to enable the converter. Connecting this pin to a ground when FB drops too far below its regulated voltage. resistor divider from VIN to ground allows programming a Connect a pull-up resistor from this pin to a positive sup- VIN start threshold higher than the 1.8V (typical) VIN UVLO ply. This pin can sink up to the absolute maximum rating threshold. In this case, the typical VIN turn-on threshold is of 15mA when low. Refer to the Operation section of the determined by VIN = 1.22V • [1+(R3/R4)] (see Figure 2). data sheet for more detail.
MPPC (Pin 5/Pin 3):
Maximum Power Point Control Pro-
V
gramming Pin. Connect this pin to a resistor divider from
OUT (Pin 12/Pin 10):
Output voltage of the converter. Connect a minimum value of 4.7µF ceramic capacitor from VIN to ground to enable the MPPC functionality. If the VOUT this pin to the ground plane, as close to the pin as possible. load is greater than what the power source can provide, the MPPC will reduce the inductor current to regulate V
BST2 (Pin 13/Pin 11):
Bootstrapped floating supply for IN to a voltage determined by: V high side NMOS gate drive. Connect to SW2 through a IN = 1.175V • [1+(R5/R6)] (see Figure 3). By setting the V 22nF capacitor, as close to the part as possible. The value IN regulation voltage appro- priately, maximum power transfer from the limited source is not critical. Any value from 4.7nF to 47nF may be used. is assured. Note this pin is very noise sensitive, therefore
SW2 (Pin 14/Pin 12):
Switch Pin. Connect to one side of minimize trace length and stray capacitance. Please refer the inductor. Keep PCB trace lengths as short and wide to the Applications Information section for more detail as possible to reduce EMI. on programming the MPPC for different sources. If this function is not needed, tie the pin to V
PGND (Pin 15, Exposed Pad Pin 17/Pin 13, Exposed
CC.
Pad Pin 17):
Power Ground. Provide a short direct PCB
GND (Pin 6/Pin 4):
Signal Ground. Provide a short direct path between PGND and the ground plane.
The exposed
PCB path between GND and the ground plane where the
pad must also be soldered to the PCB ground plane
. It exposed pad is soldered. serves as a power ground connection, and as a means of
FB (Pin 7/Pin 5):
Feedback Input to the Error Amplifier. conducting heat away from the die. Connect to a resistor divider from VOUT to ground. The
SW1 (Pin 16/Pin 14):
Switch Pin. Connect to one side of output voltage can be adjusted from 1.4V to 15.75V by: the inductor. Keep PCB trace lengths as short and wide as possible to reduce EMI. 3129fc 8 For more information www.linear.com/LTC3129 Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Typical Applications Package Description Revision History Typical Application Related Parts
pin FuncTions (QFN/MSOP) BST1 (Pin 1/Pin 15):
Bootstrapped Floating Supply for VOUT = 1.175V • [1+(R1/R2)]. Note this pin is very noise High Side NMOS Gate Drive. Connect to SW1 through a sensitive, therefore minimize trace length and stray ca- 22nF capacitor, as close to the part as possible. The value pacitance. is not critical. Any value from 4.7nF to 47nF may be used.
NC (Pins 8, 9/Pins 6, 7):
Unused. These pins should be
VIN (Pin 2/Pin 16):
Input Voltage for the Converter. Connect grounded. a minimum of 4.7µF ceramic decoupling capacitor from
PWM (Pin 10/Pin 8):
Mode Select Pin. this pin to the ground plane, as close to the pin as possible. PWM = Low (ground): Enables automatic Burst Mode
VCC (Pin 3/Pin 1):
Output voltage of the internal voltage operation. regulator. This is the supply pin for the internal circuitry. Bypass this output with a minimum of 2.2µF ceramic PWM = High (tie to VCC): Fixed frequency PMW opera- capacitor close to the pin. This pin may be back-driven by tion. an external supply, up to a maximum of 5.5V. This pin should not be allowed to float. It has an internal
RUN (Pin 4/Pin 2):
Input to the Run Comparator. Pull 5M pull-down resistor. this pin above 1.1V to enable the VCC regulator and above
PGOOD (Pin 11/Pin 9):
Open drain output that pulls to 1.28V to enable the converter. Connecting this pin to a ground when FB drops too far below its regulated voltage. resistor divider from VIN to ground allows programming a Connect a pull-up resistor from this pin to a positive sup- VIN start threshold higher than the 1.8V (typical) VIN UVLO ply. This pin can sink up to the absolute maximum rating threshold. In this case, the typical VIN turn-on threshold is of 15mA when low. Refer to the Operation section of the determined by VIN = 1.22V • [1+(R3/R4)] (see Figure 2). data sheet for more detail.
MPPC (Pin 5/Pin 3):
Maximum Power Point Control Pro-
V
gramming Pin. Connect this pin to a resistor divider from
OUT (Pin 12/Pin 10):
Output voltage of the converter. Connect a minimum value of 4.7µF ceramic capacitor from VIN to ground to enable the MPPC functionality. If the VOUT this pin to the ground plane, as close to the pin as possible. load is greater than what the power source can provide, the MPPC will reduce the inductor current to regulate V
BST2 (Pin 13/Pin 11):
Bootstrapped floating supply for IN to a voltage determined by: V high side NMOS gate drive. Connect to SW2 through a IN = 1.175V • [1+(R5/R6)] (see Figure 3). By setting the V 22nF capacitor, as close to the part as possible. The value IN regulation voltage appro- priately, maximum power transfer from the limited source is not critical. Any value from 4.7nF to 47nF may be used. is assured. Note this pin is very noise sensitive, therefore
SW2 (Pin 14/Pin 12):
Switch Pin. Connect to one side of minimize trace length and stray capacitance. Please refer the inductor. Keep PCB trace lengths as short and wide to the Applications Information section for more detail as possible to reduce EMI. on programming the MPPC for different sources. If this function is not needed, tie the pin to V
PGND (Pin 15, Exposed Pad Pin 17/Pin 13, Exposed
CC.
Pad Pin 17):
Power Ground. Provide a short direct PCB
GND (Pin 6/Pin 4):
Signal Ground. Provide a short direct path between PGND and the ground plane.
The exposed
PCB path between GND and the ground plane where the
pad must also be soldered to the PCB ground plane
. It exposed pad is soldered. serves as a power ground connection, and as a means of
FB (Pin 7/Pin 5):
Feedback Input to the Error Amplifier. conducting heat away from the die. Connect to a resistor divider from VOUT to ground. The
SW1 (Pin 16/Pin 14):
Switch Pin. Connect to one side of output voltage can be adjusted from 1.4V to 15.75V by: the inductor. Keep PCB trace lengths as short and wide as possible to reduce EMI. 3129fc 8 For more information www.linear.com/LTC3129 Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Typical Applications Package Description Revision History Typical Application Related Parts