Datasheet LTC3412A (Analog Devices) - 8
| Manufacturer | Analog Devices |
| Description | 3A, 4MHz, Monolithic Synchronous Step-Down Regulator |
| Pages / Page | 20 / 8 — FUNCTIONAL BLOCK DIAGRAM. OPERATION Main Control Loop |
| File Format / Size | PDF / 460 Kb |
| Document Language | English |
FUNCTIONAL BLOCK DIAGRAM. OPERATION Main Control Loop
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Text Version of Document
LTC3412A
FUNCTIONAL BLOCK DIAGRAM
PV SVIN SGND I IN TH 1 8 3 9 16 VOLTAGE SLOPE PMOS CURRENT REFERENCE COMPENSATION COMPARATOR RECOVERY 0.8V BCLAMP + + – – P-CH VFB 4 – ERROR AMPLIFIER + BURST SYNC/MODE +– COMPARATOR 0.74V + 10 SLOPE 11 – COMPENSATION OSCILLATOR SW 14 15 + RUN/SS 7 RUN N-CH LOGIC 0.86V – + PGOOD 2 – NMOS CURRENT COMPARATOR – + REVERSE 12 CURRENT PGND COMPARATOR 13 5 6 3412 FBD RT SYNC/MODE
OPERATION Main Control Loop
comparing the feedback signal from a resistor divider on The LTC3412A is a monolithic, constant-frequency, current the VFB pin with an internal 0.8V reference. When the load mode step-down DC/DC converter. During normal opera- current increases, it causes a reduction in the feedback tion, the internal top power switch (P-channel MOSFET) is voltage relative to the reference. The error amplifier raises turned on at the beginning of each clock cycle. Current in the ITH voltage until the average inductor current matches the inductor increases until the current comparator trips the new load current. When the top power MOSFET shuts and turns off the top power MOSFET. The peak inductor off, the synchronous power switch (N-channel MOSFET) current at which the current comparator shuts off the top turns on until either the bottom current limit is reached or power switch is controlled by the voltage on the I the beginning of the next clock cycle. The bottom current TH pin. The error amplifier adjusts the voltage on the I limit is set at –1.3A for forced continuous mode and 0A TH pin by for Burst Mode operation. 3412aff 8 Fo F r o rmo m r o e r e inf n o f r o m r a m t a iton o n ww w w w . w line n a e r a .rco c m o / m L / T L C T 3 C 4 3 1 4 2 1 A 2 Document Outline Features Applications Description Typical Application 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 Related Parts
FUNCTIONAL BLOCK DIAGRAM
PV SVIN SGND I IN TH 1 8 3 9 16 VOLTAGE SLOPE PMOS CURRENT REFERENCE COMPENSATION COMPARATOR RECOVERY 0.8V BCLAMP + + – – P-CH VFB 4 – ERROR AMPLIFIER + BURST SYNC/MODE +– COMPARATOR 0.74V + 10 SLOPE 11 – COMPENSATION OSCILLATOR SW 14 15 + RUN/SS 7 RUN N-CH LOGIC 0.86V – + PGOOD 2 – NMOS CURRENT COMPARATOR – + REVERSE 12 CURRENT PGND COMPARATOR 13 5 6 3412 FBD RT SYNC/MODE
OPERATION Main Control Loop
comparing the feedback signal from a resistor divider on The LTC3412A is a monolithic, constant-frequency, current the VFB pin with an internal 0.8V reference. When the load mode step-down DC/DC converter. During normal opera- current increases, it causes a reduction in the feedback tion, the internal top power switch (P-channel MOSFET) is voltage relative to the reference. The error amplifier raises turned on at the beginning of each clock cycle. Current in the ITH voltage until the average inductor current matches the inductor increases until the current comparator trips the new load current. When the top power MOSFET shuts and turns off the top power MOSFET. The peak inductor off, the synchronous power switch (N-channel MOSFET) current at which the current comparator shuts off the top turns on until either the bottom current limit is reached or power switch is controlled by the voltage on the I the beginning of the next clock cycle. The bottom current TH pin. The error amplifier adjusts the voltage on the I limit is set at –1.3A for forced continuous mode and 0A TH pin by for Burst Mode operation. 3412aff 8 Fo F r o rmo m r o e r e inf n o f r o m r a m t a iton o n ww w w w . w line n a e r a .rco c m o / m L / T L C T 3 C 4 3 1 4 2 1 A 2 Document Outline Features Applications Description Typical Application 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 Related Parts
