 |
Electronic Components Datasheet Search |
|
|
Electronic Components Datasheet Search |
|
EN6337QI3 Datasheet(PDF) 11 Page - Enpirion, Inc. |
|
||||||||||||||||||||||||||||||
EN6337QI3 Datasheet(HTML) 11 Page - Enpirion, Inc. |
|
|
11 / 17 page  05800 6/17/2011 Rev: B EN6337QI ©Enpirion 2011 all rights reserved, E&OE 11 www.enpirion.com Light Load Mode (LLM) Operation The EN6337QI uses a proprietary light load mode to provide high efficiency at low output currents. When the LLM/SYNC pin is high, the device is in automatic LLM “Detection” mode. When the LLM/SYNC pin is low, the device is forced into PWM mode. In automatic LLM “Detection” mode, when a light load condition is detected, the device will: (1) Step VOUT up by approximately 1.0% above the nominal operating output voltage setting, VNOM and as low as -0.5% below VNOM, and then (2) Shut down unnecessary circuitry, and then (3) Monitor VOUT. When VOUT falls below VNOM, the device will repeat (1), (2), and (3). The voltage step up, or pre-positioning, improves transient droop when a load transient causes a transition from LLM mode to PWM mode. If a load transient occurs, causing VOUT to fall below the threshold VMIN, the device will exit LLM operation and begin normal PWM operation. Figure 5 demonstrates VOUT behavior during transition into and out of LLM operation. VOUT IOUT LLM Ripple PWM Ripple VMAX VNOM VMIN Load Step Figure 5 : VOUT behavior in LLM operation. Many multi-mode DCDC converters suffer from a condition that occurs when the load current increases only slowly so that there is no load transient driving VOUT below the VMIN threshold. In this condition, the device would never exit LLM operation. This could adversely affect efficiency and cause unwanted ripple. To prevent this from occurring, the EN6337QI periodically exits LLM mode into PWM mode and measures the load current. If the load current is above the LLM threshold current, the device will remain in PWM mode. If the load current is below the LLM threshold, the device will re-enter LLM operation. There may be a small overshoot or undershoot in VOUT when the device exits and re-enters LLM. The load current at which the device will enter LLM mode is a function of input and output voltage, and the RLLM pin resistor. Contact Enpirion Applications support for details regarding the optimization of this resistor for specific operating conditions. For PWM only operation, the RLLM pin can be left open. To ensure normal LLM operation, LLM mode should be enabled and disabled with specific sequencing. For applications with explicit LLM pin control, enable LLM after VIN ramp up is complete. For applications with only ENABLE control, tie LLM to ENABLE; enable the device after VIN ramp up is complete, and disable the device before VIN ramp down begins. For designs with ENABLE and LLM tied to VIN, make sure the device soft-start time is longer than the VIN ramp-up time. LLM will start operating after the soft-start time is completed. NOTE: For proper LLM operation the EN6337QI requires a minimum difference between VIN and VOUT, and a minimum LLM load requirement as specified in the Electrical Characteristics Table. For LLM designs requiring lower voltage headroom or a lower minimum load, contact Enpirion Applications support. Over-Current Protection The current limit function is achieved by sensing the current flowing through the Power PFET. When the sensed current exceeds the over current trip point, both power FETs are turned off for the remainder of the switching cycle. If the over-current condition is removed, the over-current protection circuit will enable normal PWM operation. If the over-current condition persists, the soft start capacitor will gradually discharge causing the output voltage to fall. When the OCP fault is removed, the output voltage will ramp back up to the desired voltage. This circuit is designed to provide high noise immunity. |
Similar Part No. - EN6337QI3 |
|
Similar Description - EN6337QI3 |
|
|
|
Link URL |
| Privacy Policy |
| ALLDATASHEET.COM |
| Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Datasheet Upload | Contact us | Privacy Policy | Link Exchange | Manufacturer List All Rights Reserved©Alldatasheet.com |
| Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
|
Family Site : ic2ic.com |
icmetro.com |
English ▼
English
Chinese
German
Japanese
Russian
Korean
Spanish
French
Italian
Portuguese
Polish
Vietnamese
Indian
Mexican
British
New Zealand
