Datasheet LTM8078 (Analog Devices) - 10
| Hersteller | Analog Devices |
| Beschreibung | Dual 1.4A, Single 2.8A Step-Down Silent Switcher μModule Regulator |
| Seiten / Seite | 24 / 10 — PIN FUNCTIONS VIN1 (Pin A3):. FB1/FB2 (Pins D7, C7):. VIN2 (Pin A4):. … |
| Dateiformat / Größe | PDF / 1.7 Mb |
| Dokumentensprache | Englisch |
PIN FUNCTIONS VIN1 (Pin A3):. FB1/FB2 (Pins D7, C7):. VIN2 (Pin A4):. PG1/PG2 (Pins B1, A2):. VOUT1/VOUT2 (Banks 1 and 2):
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PIN FUNCTIONS VIN1 (Pin A3):
Input Power for the Channel 1 Regulator. phase, duty cycle, and frequency as the SYNC waveform. The VIN1 bank powers the internal control circuitry for In Burst Mode operation, the CLKOUT pin will be internally both channels and is monitored by under voltage lockout grounded. Float this pin if the CLKOUT function is not circuitry. The VIN1 voltage must be greater than 3.0V for used. Do not drive this pin. either channel of the LTM8078 to operate. Decouple VIN1
FB1/FB2 (Pins D7, C7):
The LTM8078 regulates the FBn to ground with an external, low ESR capacitor. See Table 1 pins to 800mV. Connect the feedback resistor to this pin for recommended values. to set the output voltage.
VIN2 (Pin A4):
Input Power for the Channel 2 Regulator.
PG1/PG2 (Pins B1, A2):
The PGn pins are the open-drain The VIN2 pin is monitored by under voltage lockout cir- outputs of an internal comparator. PGn remains low until cuitry. The VIN1 voltage must be greater than 3.0V and the FBn pin is within ±7.5% of the final regulation voltage, VIN2 must be greater than 2V for proper VIN2 operation. and there are no fault conditions. PGn is pul ed low during Decouple VIN2 to ground with an external, low ESR capaci- V tor. See Table 1 for recommended values. IN1 UVLO, VIN2 UVLO, thermal shutdown, or when the RUN pin is low.
VOUT1/VOUT2 (Banks 1 and 2):
Power Output for channels
RT (Pin B7):
Connect a resistor between RT and ground 1 and 2, Respectively. Apply the output filter capacitor and to set the switching frequency of both channels. Do not the output load between these pins and GND pins. drive this pin.
GND (Bank 3, Pin A7):
Tie these GND pins to a local
RUN (Pin A5):
The LTM8078 is shut down when this pin ground plane below the LTM8078 and the circuit compo- is low and active when this pin is high. Tie to V nents. In most applications, the bulk of the heat flow out of INn if shutdown feature is not used. An external resistor divider the LTM8078 is through these pads, so the printed circuit from V design has a large impact on the thermal performance of INn can be used to program a VINn threshold below which the corresponding channel of the LTM8078 will the part. See the PCB Layout and Thermal Considerations shut down. Do not float this pin. sections for more details. Return the feedback divider (RFB) to this net.
OM (Pin C6):
Output Mode. Tie this pin to the adjacent OMC pin when the two LTM8078 outputs are regulating
BIAS (Pin E7):
The internal regulator will draw current at different voltages. Float this pin when the two LTM8078 from BIAS instead of VIN1 when BIAS is tied to a voltage outputs are in parallel. higher than 3.2V. For output voltages of 3.3V and above this pin should be tied to VOUT. If this pin is tied to a sup-
OMC (Pin D6):
Output Mode Control. Float this pin when ply other than VOUT connect a local bypass capacitor to the two outputs of the LTM8078 are load sharing. Connect this pin. this pin to the OMC pin of other LTM8078s when mul- tiple LTM8078s are load sharing. When not load sharing,
CLKOUT (Pin D1):
Synchronization Output. When tie this pin to the adjacent OM pin. That is, when the SYNC > 2.8V, the CLKOUT pin provides a waveform about V 90 degrees out-of-phase with Channel 1. This allows syn- OUT1 and VOUT2 are independent voltages, connect OM to OMC. If V chronization with other regulators with up to four phases. OUT1 and VOUT2 are independent and OM and OMC are not connected together, the LTM8078 will not When an external clock is applied to the SYNC pin, the regulate properly. CLKOUT pin will output a waveform with about the same Rev. 0 10 For more information www.analog.com 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 Application Package Description Package Photograph Related Parts
PIN FUNCTIONS VIN1 (Pin A3):
Input Power for the Channel 1 Regulator. phase, duty cycle, and frequency as the SYNC waveform. The VIN1 bank powers the internal control circuitry for In Burst Mode operation, the CLKOUT pin will be internally both channels and is monitored by under voltage lockout grounded. Float this pin if the CLKOUT function is not circuitry. The VIN1 voltage must be greater than 3.0V for used. Do not drive this pin. either channel of the LTM8078 to operate. Decouple VIN1
FB1/FB2 (Pins D7, C7):
The LTM8078 regulates the FBn to ground with an external, low ESR capacitor. See Table 1 pins to 800mV. Connect the feedback resistor to this pin for recommended values. to set the output voltage.
VIN2 (Pin A4):
Input Power for the Channel 2 Regulator.
PG1/PG2 (Pins B1, A2):
The PGn pins are the open-drain The VIN2 pin is monitored by under voltage lockout cir- outputs of an internal comparator. PGn remains low until cuitry. The VIN1 voltage must be greater than 3.0V and the FBn pin is within ±7.5% of the final regulation voltage, VIN2 must be greater than 2V for proper VIN2 operation. and there are no fault conditions. PGn is pul ed low during Decouple VIN2 to ground with an external, low ESR capaci- V tor. See Table 1 for recommended values. IN1 UVLO, VIN2 UVLO, thermal shutdown, or when the RUN pin is low.
VOUT1/VOUT2 (Banks 1 and 2):
Power Output for channels
RT (Pin B7):
Connect a resistor between RT and ground 1 and 2, Respectively. Apply the output filter capacitor and to set the switching frequency of both channels. Do not the output load between these pins and GND pins. drive this pin.
GND (Bank 3, Pin A7):
Tie these GND pins to a local
RUN (Pin A5):
The LTM8078 is shut down when this pin ground plane below the LTM8078 and the circuit compo- is low and active when this pin is high. Tie to V nents. In most applications, the bulk of the heat flow out of INn if shutdown feature is not used. An external resistor divider the LTM8078 is through these pads, so the printed circuit from V design has a large impact on the thermal performance of INn can be used to program a VINn threshold below which the corresponding channel of the LTM8078 will the part. See the PCB Layout and Thermal Considerations shut down. Do not float this pin. sections for more details. Return the feedback divider (RFB) to this net.
OM (Pin C6):
Output Mode. Tie this pin to the adjacent OMC pin when the two LTM8078 outputs are regulating
BIAS (Pin E7):
The internal regulator will draw current at different voltages. Float this pin when the two LTM8078 from BIAS instead of VIN1 when BIAS is tied to a voltage outputs are in parallel. higher than 3.2V. For output voltages of 3.3V and above this pin should be tied to VOUT. If this pin is tied to a sup-
OMC (Pin D6):
Output Mode Control. Float this pin when ply other than VOUT connect a local bypass capacitor to the two outputs of the LTM8078 are load sharing. Connect this pin. this pin to the OMC pin of other LTM8078s when mul- tiple LTM8078s are load sharing. When not load sharing,
CLKOUT (Pin D1):
Synchronization Output. When tie this pin to the adjacent OM pin. That is, when the SYNC > 2.8V, the CLKOUT pin provides a waveform about V 90 degrees out-of-phase with Channel 1. This allows syn- OUT1 and VOUT2 are independent voltages, connect OM to OMC. If V chronization with other regulators with up to four phases. OUT1 and VOUT2 are independent and OM and OMC are not connected together, the LTM8078 will not When an external clock is applied to the SYNC pin, the regulate properly. CLKOUT pin will output a waveform with about the same Rev. 0 10 For more information www.analog.com 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 Application Package Description Package Photograph Related Parts