ZHCSKX9D May 2019 – July 2022 LM61460
PRODUCTION DATA
- 1 特性
- 2 應用
- 3 說明
- 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 EN/SYNC Uses for Enable and VIN UVLO
- 8.3.2 EN/SYNC Pin Uses for Synchronization
- 8.3.3 Clock Locking
- 8.3.4 Adjustable Switching Frequency
- 8.3.5 PGOOD Output Operation
- 8.3.6 Internal LDO, VCC UVLO, and BIAS Input
- 8.3.7 Bootstrap Voltage and VCBOOT-UVLO (CBOOT Pin)
- 8.3.8 Adjustable SW Node Slew Rate
- 8.3.9 Spread Spectrum
- 8.3.10 Soft Start and Recovery From Dropout
- 8.3.11 Output Voltage Setting
- 8.3.12 Overcurrent and Short Circuit Protection
- 8.3.13 Thermal Shutdown
- 8.3.14 Input Supply Current
- 8.4 Device Functional Modes
- 9 Application and Implementation
- 10Power Supply Recommendations
- 11Layout
- 12Device and Documentation Support
- 13Mechanical, Packaging, and Orderable Information
6 Pin Configuration and Functions
Figure 6-1 14-Pin VQFN-HR RJR Package
(Top View)Table 6-1 Pin Functions
| PIN | I/O | DESCRIPTION | |
|---|---|---|---|
| NAME | NO. | ||
| BIAS | 1 | P | Input to internal LDO. Connect to the output voltage point to improve efficiency. Connect an optional high quality 0.1-μF to 1-μF capacitor from this pin to ground for improved noise immunity. If output voltage is above 12 V, connect this pin to ground. |
| VCC | 2 | O | Internal LDO output. Used as a supply to internal control circuits. Do not connect to any external loads. Connect a high-quality 1-μF capacitor from this pin to AGND. |
| AGND | 3 | G | Analog ground for internal circuitry. Feedback and VCC are measured with respect to this pin. Must connect AGND to both PGND1 and PGND2 on PCB. |
| FB | 4 | I | Output voltage feedback input to the internal control loop. Connect to the feedback divider tap point for adjustable output voltage. Do not float or connect to ground. |
| PGOOD | 5 | O | Open-drain power-good status output. Pull this pin up to a suitable voltage supply through a current limiting resistor. High = power OK, low = fault. PGOOD output goes low when EN = low, VIN > 1 V. |
| RT | 6 | I/O | Connect this pin to ground through a resistor with value between 5.76 kΩ and 66.5 kΩ to set switching frequency between 200 kHz and 2200 kHz. Do not float or connect to ground. |
| EN/SYNC | 7 | I | Precision enable input. High = on, Low = off. Can be connected to VIN. Precision enable allows the pin to be used as an adjustable UVLO. See Section 9. Do not float. EN/SYNC also functions as a synchronization input pin. Used to synchronize the device switching frequency to a system clock. Triggers on rising edge of an external clock. A capacitor can be used to AC couple the synchronization signal to this pin. When synchronized to an external clock, the device functions in forced PWM and disables the PFM light load efficiency mode. See Section 8. |
| VIN1 | 8 | P | Input supply to the converter. Connect a high-quality bypass capacitor or capacitors from this pin to PGND1. Low impedance connection must be provided to VIN2. |
| PGND1 | 9 | G | Power ground to the internal low-side MOSFET. Connect to system ground. Low impedance connection must be provided to PGND2. Connect a high-quality bypass capacitor or capacitors from this pin to VIN1. |
| SW | 10 | O | Switch node of the converter. Connect to the output inductor. |
| PGND2 | 11 | G | Power ground to the internal low-side MOSFET. Connect to system ground. Low impedance connection must be provided to PGND1. Connect a high-quality bypass capacitor or capacitors from this pin to VIN2. |
| VIN2 | 12 | P | Input supply to the converter. Connect a high-quality bypass capacitor or capacitors from this pin to PGND2. Low impedance connection must be provided to VIN1. |
| RBOOT | 13 | I/O | Connect to CBOOT through a resistor. This resistance must be between 0 Ω and open. This resistance determines SW node rise time. |
| CBOOT | 14 | I/O | High-side driver upper supply rail. Connect a 100-nF capacitor between SW and CBOOT. An internal diode connects to VCC and allows CBOOT to charge while SW node is low. |