Texas Instruments Evaluation Board for the LM10506 LM10506EVAL/NOPB LM10506EVAL/NOPB Datenbogen
Produktcode
LM10506EVAL/NOPB
SNVS729E – SEPTEMBER 2011 – REVISED MARCH 2013
STANDBY Pin
When the STANDBY pin is asserted high, the LM10506 will enter Standby Mode. While in Standby Mode, Buck 1
and Buck 2 are disabled. Buck 3’s output voltage is transitioned to the PSML (Programmable Standby Mode
Level) as set by register 0x09. The STANDBY pin is internally pulled down, and there is a 1 second delay during
powerup before the state of the STANDBY pin is checked.
and Buck 2 are disabled. Buck 3’s output voltage is transitioned to the PSML (Programmable Standby Mode
Level) as set by register 0x09. The STANDBY pin is internally pulled down, and there is a 1 second delay during
powerup before the state of the STANDBY pin is checked.
NOTE
If Buck 1 and Buck 2 are already disabled, and the STANDBY pin is asserted high, then
Buck 3 will not go to PSML – for further instructions, see
Buck 3 will not go to PSML – for further instructions, see
Bucks 1 and 2 will be ramped down when the disable signal is given. Buck 1 starts ramping 2ms after Buck 2
has started ramping.
has started ramping.
Entering Standby Sequence will be:
1. Buck 3
→
PSML (Programmable Standby Mode Level)
2. 2 msec delay
3. Buck 2
→
Disabled
4. 2 msec delay
5. Buck 1
→
Disabled
An internal 22 k
Ω
pull down resistor (±30%) is attached to the FB pin of Buck 1 and Buck 2. Buck 1 and 2
outputs are pulled to ground level when they are disabled to discharge any residual charge present in the output
circuitry. When STANDBY transitions to a low, Buck 1 is again enabled followed by Buck 2. Buck 3 will go back
to its previous state.
circuitry. When STANDBY transitions to a low, Buck 1 is again enabled followed by Buck 2. Buck 3 will go back
to its previous state.
When waking up from Standby, the sequence will be:
1. Buck 1
→
Previous State
2. 2 msec delay
3. Buck 2 and Buck 3 transition together
→
Previous State
STANDBY Programming via SPI
There is no bit which has the same function as STANDBY PIN. There is only one requirement programming
LM10506 into Standby Mode via SPI. Setting LDO Sleep Mode bit high must be the last move when entering
Standby Mode and programming the bit low when waking from Standby Mode must be the first move. Disabling
or programming the Bucks to new level is the user’s decision based on power consumption and other
requirements.
LM10506 into Standby Mode via SPI. Setting LDO Sleep Mode bit high must be the last move when entering
Standby Mode and programming the bit low when waking from Standby Mode must be the first move. Disabling
or programming the Bucks to new level is the user’s decision based on power consumption and other
requirements.
The following section describes how to program the chip into Standby Mode corresponding to STANDBY PIN
function. To program the LM10506 to Standby Mode via SPI Buck 1 and Buck 2 must be disabled by host device
(Register 0x0A bit 1 and 0). Buck 3 must be programmed to desired level using Register 0x00. After Buck 3 has
finished ramping LDO Sleep Mode bit must be set high (Register 0x0E bit 1). To wake LM10506 from Standby
Mode LDO Sleep Mode bit must be set low (Register 0x0E bit 1). Buck 1 and 2 must be enabled. Buck 3 voltage
must be programmed to previous output level. For LM10506 -C, -D,when Buck 1 is re-enabled upon exiting
STANDBY, soft start will engage.
function. To program the LM10506 to Standby Mode via SPI Buck 1 and Buck 2 must be disabled by host device
(Register 0x0A bit 1 and 0). Buck 3 must be programmed to desired level using Register 0x00. After Buck 3 has
finished ramping LDO Sleep Mode bit must be set high (Register 0x0E bit 1). To wake LM10506 from Standby
Mode LDO Sleep Mode bit must be set low (Register 0x0E bit 1). Buck 1 and 2 must be enabled. Buck 3 voltage
must be programmed to previous output level. For LM10506 -C, -D,when Buck 1 is re-enabled upon exiting
STANDBY, soft start will engage.
STANDBY MODE, Operational Constraints
In Standby mode the device is in a low power mode. All internal clocks are turned off to conserve power and
BUCK 3 will only operate in PFM mode. While limited to PFM mode the loading on BUCK 3 should be kept below
80mA typ. to remain below the PFM/PWM threshold and avoid device shutdown. It is recommended that the
device loading should be lowered accordingly prior to entering standby mode via STANDBY.
BUCK 3 will only operate in PFM mode. While limited to PFM mode the loading on BUCK 3 should be kept below
80mA typ. to remain below the PFM/PWM threshold and avoid device shutdown. It is recommended that the
device loading should be lowered accordingly prior to entering standby mode via STANDBY.
Copyright © 2011–2013, Texas Instruments Incorporated
25
Product Folder Links: