JAJSRX5 データシート

JAJSRX5 November 2023 LM5185

PRODUCTION DATA

パッケージ・オプション

7.3.6 Precision Enable

The precision EN/UVLO input supports adjustable input undervoltage lockout (UVLO) with hysteresis for application specific power-up and power-down requirements. EN/UVLO connects to a comparator with a 1.5-V reference voltage and 50-mV hysteresis. An external logic signal can be used to drive the EN/UVLO input to toggle the output on and off for system sequencing or protection. The simplest way to enable the LM5185 is to connect EN/UVLO directly to V_IN. This connection allows the LM5185 to start up when V_IN is within the valid operating range. However, many applications benefit from using resistor divider R_UV1 and R_UV2 as shown in Figure 7-4 to establish a precision UVLO level.

Figure 7-4 Programmable Input Voltage UVLO With Hysteresis

Use Equation 10 and Equation 11 to calculate the input UVLO voltages turn-on and turn-off voltages, respectively.

Equation 10.

V_{I N (O N)} = V_{U V - R I S I N G} \times (1 + \frac{R_{U V 1}}{R_{U V 2}})

where

V_UV-RISING and V_UV-FALLING are the UVLO comparator thresholds
I_UV-HYST is the hysteresis current

Equation 11.

V_{I N (O F F)} = V_{U V - F A L L I N G} \times (1 + \frac{R_{U V 1}}{R_{U V 2}}) - I_{U V - H Y S T} \times R_{U V 1}

The LM5185 also provides a low-I_Q shutdown mode when the EN/UVLO voltage is pulled below a base-emitter voltage drop (approximately 0.6 V at room temperature). If the EN/UVLO voltage is below this hard shutdown threshold, the internal LDO regulator powers off, and the internal bias-supply rail collapses, shutting down the bias currents of the LM5185. The LM5185 operates in standby mode when the EN/UVLO voltage is between the hard shutdown and precision-enable thresholds.

パッケージ・オプション

メカニカル・データ（パッケージ｜ピン）

サーマルパッド・メカニカル・データ

発注情報

7.3.6 Precision Enable