ZHCSG19 March 2017 LM25141
PRODUCTION DATA.
| PIN | TYPE | DESCRIPTION | |
|---|---|---|---|
| NO. | NAME | ||
| 1 | DEMB | I | Diode Emulation pin. Connect the DEMB pin to AGND to enable diode emulation. If it is connected to VDDA the LM5141 operates in Forced PWM (FPWM) mode with continuous conduction at light loads. The DEMB pin can also be used as a synchronization input, to synchronize the internal oscillator to an external clock. |
| 2 | VDDA | P | Internal analog bias regulator output. Connect a capacitor from the VDDA pin to AGND. |
| 3 | AGND | G | Analog ground connection. Ground return for the internal voltage reference and analog circuits. |
| 4 | RT | I | A resistor from the RT pin to ground shifts the oscillator frequency up or down from 2.2 MHz (1.8 MHz to 2.53 MHz), or 440 kHz (300 kHz to 500 kHz). An analog voltage can be applied to the RT pin (through a resistor) to shift the oscillator frequency. |
| 5 | DITH | O | A capacitor connected between the DITH pin and AGND is charged and discharged with a 20 µA current source. If Dither is enabled, the voltage on the DITH pin ramps up and down modulating the oscillator frequency between –5% and +5% of the internal oscillator. Connecting DITH to VDDA will disable the dithering feature. DITH is ignored if an external synchronization clock is used. |
| 6 | OSC | I | Frequency selection pin. Connecting the OSC pin to VDDA sets the oscillator frequency to 2.2 MHz. Connecting the OSC pin to AGND sets the frequency to 440 kHz. |
| 7 | LOL | O | Low-side gate driver turn-off output. |
| 8 | LO | O | Low-side gate driver turn-on output. |
| 9 | PGND | G | Power ground connection pin for low-side NMOS gate driver. |
| 10 | VCC | P | VCC bias supply pin. Connect a capacitor from the VCC pin to PGND. |
| 11 | HB | P | High-side driver supply for bootstrap gate drive. |
| 12 | SW | Switching node of the buck regulator. Connect to the bootstrap capacitor, the source terminal of the high-side MOSFET and the drain terminal of the low-side MOSFET. | |
| 13 | HO | O | High-side gate driver turn-on output. |
| 14 | HOL | O | High-side gate driver turn-off output. |
| 15 | VIN | P | Supply voltage input source for the VCC regulator |
| 16 | VCCX | P | Optional input for an external bias supply. If VCCX > 4.5 V, VCCX is internally connected to the VCC pin and the internal VCC regulator is disabled. If VCCX is unused, it should be grounded. |
| 17 | VOUT | I | Current sense amplifier input. Connect this pin to the output side of the current sense resistor. |
| 18 | CS | I | Current sense amplifier input. Make a low current Kelvin connection between this pin and the inductor side of the external current sense resistor. |
| 19 | FB | I | Connect the FB pin to VDDA for a fixed 3.3-V output or connect FB to AGND for a fixed 5-V output. Connecting the FB pin to the appropriate output divider network will set the output voltage between 1.5 V and 15 V. The regulation threshold at the FB pin is 1.2 V. |
| 20 | COMP | I | Output of the transconductance error amplifier. |
| 21 | PG | O | An open collector output which switches low if VOUT is outside of the power good window. |
| 22 | SS | I | Soft-start programming pin. An external capacitor and an internal 20-μA current source set the ramp rate of the internal error amplifier reference during soft-start. Pulling SS pin below 80 mV turns-off the gate driver outputs, but all the other functions remain active. |
| 23 | EN | I | An active high logic input enables the controller. |
| 24 | RES | O | Restart timer pin. An external capacitor configures the hiccup mode current limiting. The capacitor at the RES pin determines the time the controller will remain off before automatically restarting in hiccup mode. The hiccup mode commences when the controller experiences 512 consecutive PWM cycles with cycle-by-cycle current limiting. Connecting the RES pin to VDD during power up disables hiccup mode protection. |