SNVSAO4D December 2017 – August 2020 LMZM33602
PRODUCTION DATA
- 1Features
- 2Applications
- 3Description
- 4Revision History
- 5Pin Configuration and Functions
- 6Specifications
-
7Detailed Description
- 7.1 Overview
- 7.2 Functional Block Diagram
- 7.3
Feature Description
- 7.3.1 Adjusting the Output Voltage
- 7.3.2 Feedforward Capacitor, CFF
- 7.3.3 Voltage Dropout
- 7.3.4 Switching Frequency (RT)
- 7.3.5 Synchronization (SYNC)
- 7.3.6 Input Capacitors
- 7.3.7 Output Capacitors
- 7.3.8 Output On/Off Enable (EN)
- 7.3.9 Programmable Undervoltage Lockout (UVLO)
- 7.3.10 Power Good (PGOOD)
- 7.3.11 Overcurrent Protection (OCP)
- 7.3.12 Thermal Shutdown
- 7.4 Device Functional Modes
- 8Application and Implementation
- 9Device and Documentation Support
7.3.4 Switching Frequency (RT)
The switching frequency range of the LMZM33602 is 200 kHz to 1.2 MHz. The switching frequency can easily be set by connecting a resistor (RRT) between the RT pin and AGND. Additionally, the RT pin can be left floating and the LMZM33602 will operate at 400 kHz default switching frequency. Use Equation 3 to calculate the RRT value for a desired frequency or simply select from Table 7-3.
The switching frequency must be selected based on the output voltage setting of the device and the operating input voltage. See Table 7-3 for RRT resistor values and the allowable output voltage range for a given switching frequency for three common input voltages.
| SWITCHING FREQUENCY (kHz) | RRT RESISTOR (kΩ) | VIN = 5 V (±5%) | VIN = 12 V (±5%) | VIN = 24 V (±5%) | |||
|---|---|---|---|---|---|---|---|
| VOUT RANGE (V) | VOUT RANGE (V) | VOUT RANGE (V) | |||||
| MIN | MAX | MIN | MAX | MIN | MAX | ||
| 200 | 200 | 1 | 3.4 | 1 | 5.5 | 1 | 6.2 |
| 250 | 158 | 1 | 3.5 | 1 | 6.2 | 1 | 10.6 |
| 300 | 133 | 1 | 3.5 | 1 | 6.8 | 1 | 10.6 |
| 350 | 113 | 1 | 3.5 | 1 | 7.4 | 1 | 10.7 |
| 400 | 100 or (RT pin open) | 1 | 3.5 | 1 | 7.9 | 1 | 11.4 |
| 450 | 88.7 | 1 | 3.5 | 1 | 8.4 | 1.2 | 12.1 |
| 500 | 78.7 | 1 | 3.5 | 1 | 8.9 | 1.3 | 12.8 |
| 550 | 71.5 | 1 | 3.4 | 1 | 9.3 | 1.4 | 13.4 |
| 600 | 66.5 | 1 | 3.4 | 1 | 9.5 | 1.6 | 14.1 |
| 650 | 60.4 | 1 | 3.4 | 1 | 9.4 | 1.7 | 14.6 |
| 700 | 56.2 | 1 | 3.3 | 1 | 9.3 | 1.8 | 15.2 |
| 750 | 52.3 | 1 | 3.3 | 1 | 9.2 | 2.0 | 15.8 |
| 800 | 49.9 | 1 | 3.3 | 1 | 9.1 | 2.1 | 16.3 |
| 850 | 46.4 | 1 | 3.2 | 1.1 | 9.0 | 2.2 | 16.8 |
| 900 | 44.2 | 1 | 3.2 | 1.2 | 9.0 | 2.3 | 17.3 |
| 950 | 41.2 | 1 | 3.2 | 1.2 | 8.9 | 2.5 | 17.8 |
| 1000 | 39.2 | 1 | 3.1 | 1.3 | 8.8 | 2.6 | 18 |
| 1050 | 37.4 | 1 | 3.1 | 1.4 | 8.7 | 2.7 | 18 |
| 1100 | 35.7 | 1 | 3.1 | 1.4 | 8.6 | 2.9 | 18 |
| 1150 | 34.0 | 1 | 3 | 1.5 | 8.5 | 3 | 18 |
| 1200 | 33.2 | 1 | 3 | 1.6 | 8.5 | 3.1 | 18 |