SNVSB23 March 2018 LP87521-Q1 , LP87522-Q1 , LP87523-Q1 , LP87524-Q1 , LP87525-Q1
PRODUCTION DATA.
The regulator(s) can be enabled when the device is in STANDBY or ACTIVE state. There are two ways for enable and disable the regulators:
If the EN1, EN2, EN3 control pins are used for enable and disable then the control pin is selected with BUCKx_EN_PIN_SELECT[1:0] bits (in BUCKx_CTRL1 register). The delay from the control signal rising edge to enabling of the regulator is set by BUCKx_STARTUP_DELAY[3:0] bits, and the delay from control signal falling edge to disabling of the regulator is set by BUCKx_SHUTDOWN_DELAY[3:0] bits in BUCKx_DELAY register. The delays are valid only for EN1, EN2, EN3 signal control. The control with EN_BUCKx bit is immediate without the delays.
The control of the regulator (with 0-ms delays) is shown in Table 3.
NOTE
The control of the regulator cannot be changed from one ENx pin to a different ENx pin because the control is ENx signal-edge sensitive. The control from ENx pin to register bit and back to the original ENx pin can be done during operation.
CONTROL METHOD | EN_BUCKx | EN_PIN_CTRLx | BUCKx_EN_PIN_SELECT[1:0] | EN_ROOF_FLOOR x | EN1 PIN | EN2 PIN | EN3 PIN | BUCKx
OUTPUT VOLTAGE |
---|---|---|---|---|---|---|---|---|
Enable and disable control with EN_BUCKx bit | 0h | Don't Care | Don't Care | Don't Care | Don't Care | Don't Care | Don't Care | Disabled |
1h | 0h | Don't Care | Don't Care | Don't Care | Don't Care | Don't Care | BUCKx_VSET[7:0] | |
Enable and disable control with EN1 pin | 1h | 1h | 0h | 0h | Low | Don't Care | Don't Care | Disabled |
1h | 1h | 0h | 0h | High | Don't Care | Don't Care | BUCKx_VSET[7:0] | |
Enable and disable control with EN2 pin | 1h | 1h | 1h | 0h | Don't Care | Low | Don't Care | Disabled |
1h | 1h | 1h | 0h | Don't Care | High | Don't Care | BUCKx_VSET[7:0] | |
Enable and disable control with EN3 pin | 1h | 1h | 2h | 0h | Don't Care | Don't Care | Low | Disabled |
1h | 1h | 2h | 0h | Don't Care | Don't Care | High | BUCKx_VSET[7:0] | |
Roof and floor control with EN1 pin | 1h | 1h | 0h | 1h | Low | Don't Care | Don't Care | BUCKx_FLOOR_VSET[7:0] |
1h | 1h | 0h | 1h | High | Don't Care | Don't Care | BUCKx_VSET[7:0] | |
Roof and floor control with EN2 pin | 1h | 1h | 1h | 1h | Don't Care | Low | Don't Care | BUCKx_FLOOR_VSET[7:0] |
1h | 1h | 1h | 1h | Don't Care | High | Don't Care | BUCKx_VSET[7:0] | |
Roof and floor control with EN3 pin | 1h | 1h | 2h | 1h | Don't Care | Don't Care | Low | BUCKx_FLOOR_VSET[7:0] |
1h | 1h | 2h | 1h | Don't Care | Don't Care | High | BUCKx_VSET[7:0] |
The regulator is enabled by the ENx pin or by I2C writing as shown in Figure 14. The soft-start circuit limits the in-rush current during start-up. When the output voltage rises to 0.35-V level, the output voltage becomes slew-rate controlled. If there is a short circuit at the output and the output voltage does not increase above 0.35-V level in 1 ms, the regulator is disabled, and interrupt is set. When the output voltage reaches the Power-Good threshold level the BUCKx_PG_INT interrupt flag (in INT_BUCK_x register) is set. The Power-Good interrupt flag can be masked using BUCKx_PG_MASK bit (in BUCKx_MASK register).
The ENx input pins have integrated pulldown resistors. The pulldown resistors are enabled by default, and the host can disable those with ENx_PD bits (in CONFIG register).