ZHCSO70A march 2023 – may 2023 LMR36501 , LMR36502
PRODUCTION DATA
- 1
- 1 特性
- 2 应用
- 3 说明
- 4 Revision History
- 5 Device Comparison Table
- 6 Pin Configuration and Functions
- 7 Specifications
-
8 Detailed Description
- 8.1 Overview
- 8.2 Functional Block Diagram
- 8.3
Feature Description
- 8.3.1 Enable, Shutdown, and Start-up
- 8.3.2 Adjustable Switching Frequency (with RT)
- 8.3.3 Power-Good Output Operation
- 8.3.4 Internal LDO, VCC UVLO, and VOUT/FB Input
- 8.3.5 Bootstrap Voltage and VBOOT-UVLO (BOOT Terminal)
- 8.3.6 Output Voltage Selection
- 8.3.7 Soft Start and Recovery from Dropout
- 8.3.8 Current Limit and Short Circuit
- 8.3.9 Thermal Shutdown
- 8.3.10 Input Supply Current
- 8.4 Device Functional Modes
-
9 Application and Implementation
- 9.1 Application Information
- 9.2
Typical Application
- 9.2.1 Design Requirements
- 9.2.2 Detailed Design Procedure
- 9.2.3 Application Curves
- 9.3 Best Design Practices
- 9.4 Power Supply Recommendations
- 9.5 Layout
- 10Device and Documentation Support
- 11Mechanical, Packaging, and Orderable Information
9.2 Typical Application
Figure 9-1 shows a typical application circuit for the LMR36502. This device is designed to function over a wide range of external components and system parameters. However, the internal compensation is optimized for a certain range of external inductance and output capacitance. As a quick-start guide, Table 9-1 and Table 9-2 provide typical component values for a range of the most common output voltages.
A. The
RT pin is factory-set for externally adjustable switching frequency RT variants
only. Tying this pin to GND results in 2.2-MHz or to VCC results in 1.1-MHz
switching frequency. See Section 8.3.2 for details.
B. The
MODE/SYNC pin is factory-set for fixed frequency frequency MODE/SYNC variants
only. Tying this pin to GND results in AUTO mode.
Figure 9-1 Example Application
CircuitTable 9-1 Typical External Component Values
for Adjustable Output LMR36502
| FSW (1) (2) (kHz) | VOUT (V) | L (µH) | NOMINAL COUT (RATED CAPACITANCE) | MINIMUM COUT (RATED CAPACITANCE) | RFBT (Ω) (3) | RFBB (Ω) | CIN | CBOOT | CVCC |
|---|---|---|---|---|---|---|---|---|---|
| 400 | 3.3 | 33 | 1 × 47 µF | 1 × 22 µF | 33.2 k | 14.3 k | 2.2 µF + 1 × 100 nF | 100 nF | 1 µF |
| 1000 | 3.3 | 15 | 2 × 22 µF | 1 × 22 µF | 33.2 k | 14.3 k | 2.2 µF + 1 × 100 nF | 100 nF | 1 µF |
| 400 | 5 | 47 | 1 × 47 µF | 1 × 22 µF | 49.9 k | 12.4 k | 2.2 µF + 1 × 100 nF | 100 nF | 1 µF |
| 1000 | 5 | 22 | 2 × 22 µF | 1 × 22 µF | 49.9 k | 12.4 k | 2.2 µF + 1 × 100 nF | 100 nF | 1 µF |
(1) Inductor values are calculated based on typical VIN = 24 V.
(2) The switching frequencies listed here can be achieved in a number of ways
depending on the device variant. For RT devices see Section 8.3.2. .
(3) For RFBT and RFBB values outside the range stated above,
see Section 9.2.2.2.1.
Table 9-2 Typical External Component Values
for Fixed Output LMR36502
| FSW (1) (2) (kHz) | VOUT (V) | L (µH) | NOMINAL COUT (RATED CAPACITANCE) | MINIMUM COUT (RATED CAPACITANCE) | RFBT (Ω) | RFBB (Ω) (3) | CIN | CBOOT | CVCC |
|---|---|---|---|---|---|---|---|---|---|
| 400 | 3.3 | 68 | 1 × 47 µF | 1 × 22 µF | 0 | DNP | 2.2 µF + 1 × 100 nF | 100 nF | 1 µF |
| 2200 | 3.3 | 10 | 1 × 10 µF | 1 × 10 µF | 0 | DNP | 2.2 µF + 1 × 100 nF | 100 nF | 1 µF |
| 400 | 5 | 82 | 1 × 47 µF | 1 × 22 µF | 0 | DNP | 2.2 µF + 1 × 100 nF | 100 nF | 1 µF |
| 2200 | 5 | 15 | 1 × 10 µF | 1 × 10 µF | 0 | DNP | 2.2 µF + 1 × 100 nF | 100 nF | 1 µF |
(1) Inductor values are calculated based on typical VIN = 13.5 V.
(2) The switching frequencies listed here can be achieved in a number of ways
depending on the device variant. For RT devices see Section 8.3.2.
(3) DNP = Do Not Populate.