The LM22677 switching regulator provides all of the functions necessary to implement an efficient high-voltage step-down (buck) regulator using a minimum of external components. This easy-to-use regulator incorporates a 42-V N-channel MOSFET switch that can provide up to 5 A of load current. Excellent line and load regulation along with high efficiency (> 90%) are featured. Voltage mode control offers short minimum on-time, allowing the widest ratio between input and output voltages. Internal loop compensation means that the user is free from the tedious task of calculating the loop compensation components. Fixed 5-V output and adjustable output voltage options are available. The default switching frequency is set at 500 kHz, thus allowing for small external components and good transient response. In addition, the frequency can be adjusted over a range of 200 kHz to 1 MHz with a single external resistor. The internal oscillator can be synchronized to a system clock or to the oscillator of another regulator. A precision enable input allows simplification of regulator control and system power sequencing. In shutdown mode the regulator draws only 25 µA (typical). The LM22677 also has built-in thermal shutdown, and current limiting to protect against accidental overloads.
The LM22677 device is a member of Texas Instruments' SIMPLE SWITCHER® family. The SIMPLE SWITCHER concept provides for an easy-to-use complete design using a minimum number of external components and the TI WEBENCH design tool. TI's WEBENCH tool includes features such as external component calculation, electrical simulation, thermal simulation, and Build-It boards for easy design-in.
PART NUMBER | PACKAGE | BODY SIZE (NOM) |
---|---|---|
LM22677 | TO-263 (7) | 10.16 mm x 9.85 mm |
LM22677-Q1 |
Changes from N Revision (November 2014) to O Revision
Changes from M Revision (April 2013) to N Revision
PIN | TYPE(1) | DESCRIPTION | APPLICATION INFORMATION | |
---|---|---|---|---|
NAME | NO. | |||
SW | 1 | O | Switch output | Switching output of regulator |
VIN | 2 | I | Input voltage | Supply input to the regulator |
BOOT | 3 | I | Bootstrap input | Provides the gate voltage for the high side N-FET |
GND | 4 | — | Ground input to regulator; system common | System ground pin |
RT/SYNC | 5 | I | Oscillator mode control input | Used to control oscillator mode of regulator. See Switching Frequency Adjustment and Synchronization section of data sheet. |
FB | 6 | I | Feedback input | Feedback input to regulator |
EN | 7 | I | Enable input | Used to control regulator start-up and shutdown. See Precision Enable and UVLO section of data sheet. |
EP | EP | — | Exposed Pad | Connect to ground. Provides thermal connection to PCB. See Applications and Implementation. |
MIN | MAX | UNIT | ||
---|---|---|---|---|
VIN to GND | 43 | V | ||
EN Pin Voltage | –0.5 | 6 | V | |
RT/SYNC Pin Voltage | –0.5 | 7 | V | |
SW to GND(3) | –5 | VIN | V | |
BOOT Pin Voltage | VSW + 7 | V | ||
FB Pin Voltage | –0.5 | 7 | V | |
Power Dissipation | Internally Limited | |||
Junction Temperature | 150 | °C | ||
For soldering specifications, refer to Application Report Absolute Maximum Ratings for Soldering (SNOA549). | ||||
Storage temperature, Tstg | –65 | 150 | °C |
VALUE | UNIT | |||
---|---|---|---|---|
V(ESD) | Electrostatic discharge | Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001(1) | ±2000 | V |
VALUE | UNIT | |||
---|---|---|---|---|
V(ESD) | Electrostatic discharge | Human-body model (HBM), per AEC Q100-002(1) | ±2000 | V |
MIN | MAX | UNIT | ||
---|---|---|---|---|
VIN | Supply Voltage | 4.5 | 42 | V |
Junction Temperature | –40 | 125 | °C |
THERMAL METRIC(1)(2) | LM22677 | UNIT | |
---|---|---|---|
NDR (TO-263) | |||
7 PINS | |||
RθJA | Junction-to-ambient thermal resistance | 22 | °C/W |
PARAMETER | TEST CONDITIONS | MIN(1) | TYP(2) | MAX(1) | UNIT | |
---|---|---|---|---|---|---|
LM22677-5.0 | ||||||
VFB | Feedback Voltage | VIN = 8 V to 42 V | 4.925 | 5.0 | 5.075 | V |
VIN = 8 V to 42 V, –40°C ≤ TJ ≤ 125°C | 4.9 | 5.1 | ||||
LM22677-ADJ | ||||||
VFB | Feedback Voltage | VIN = 4.7 V to 42 V | 1.266 | 1.285 | 1.304 | V |
VIN = 4.7 V to 42 V, –40°C ≤ TJ ≤ 125°C | 1.259 | 1.311 | ||||
ALL OUTPUT VOLTAGE VERSIONS | ||||||
IQ | Quiescent Current | VFB = 5 V | 3.4 | mA | ||
VFB = 5 V, –40°C ≤ TJ ≤ 125°C | 6 | |||||
ISTDBY | Standby Quiescent Current | EN Pin = 0 V | 25 | 40 | µA | |
ICL | Current Limit | 6.0 | 7.1 | 8.4 | A | |
–40°C ≤ TJ ≤ 125°C | 5.75 | 8.75 | ||||
IL | Output Leakage Current | VIN = 42 V, EN Pin = 0 V, VSW = 0 V | 0.2 | 2 | µA | |
VSW = –1 V | 0.1 | 3 | µA | |||
RDS(ON) | Switch On-Resistance | 0.1 | 0.14 | Ω | ||
–40°C ≤ TJ ≤ 125°C | 0.2 | |||||
fO | Oscillator Frequency | 500 | kHz | |||
–40°C ≤ TJ ≤ 125°C | 400 | 600 | ||||
TOFFMIN | Minimum Off-time | 200 | ns | |||
–40°C ≤ TJ ≤ 125°C | 100 | 300 | ||||
TONMIN | Minimum On-time | 100 | ns | |||
IBIAS | Feedback Bias Current | VFB = 1.3 V (ADJ Version Only) | 230 | nA | ||
VEN | Enable Threshold Voltage | Falling | 1.6 | V | ||
Falling, –40°C ≤ TJ ≤ 125°C | 1.3 | 1.9 | ||||
VENHYST | Enable Voltage Hysteresis | 0.6 | V | |||
IEN | Enable Input Current | EN Input = 0 V | 6 | µA | ||
FSYNC | Maximum Synchronization Frequency | VSYNC = 3.5 V, 50% duty-cycle | 1 | MHz | ||
VSYNC | Synchronization Threshold Voltage | 1.75 | V | |||
TSD | Thermal Shutdown Threshold | 150 | °C |