Datasheet BM2P139TF, BM2P135TF, BM2P137TKF, BM2P129TF (Rohm) - 7

BM2P139TF/BM2P135TF/BM2P137TKF/BM2P129TF
Datasheet Datasheet
(2) Start sequences (start-up operation, light load operation, over load protection function)
Start sequences are shown in Figure 3. See the sections below for detailed descriptions. DRAIN-GND VUVLO1 VCHG2 VCC - GND_IC VCHG1 VUVLO2 Internal 128ms VOUT - GND OVER OVER LOAD LOAD NORMAL OLP setting LOAD LIGHT 512ms IOUT LOAD 128ms 128ms BURST MODE SWITCHING A B C D E F G H I J K Figure 3. Start sequences timing chart A: Input voltage is applied to the DRAIN pin and the VCC pin voltage rises. B: If the VCC pin voltage exceeds VUVLO1, the IC starts to operate. And if the IC judges the other protection functions as normal condition, it starts switching operation. The soft start function limits the over current limiter value to prevent any excessive voltage or current rising. When the switching operation starts, the VOUT rises. C: Till the secondary input voltage becomes constant value from starting-up, the VCC pin voltage drops by the VCC pin consumption current. D: After switching starts, it is necessary that the output voltage is set to rating voltage within TFOLP1 (128ms typ). E: At light load, the IC starts burst operation to restrict the consumption power. F: When the load exceeds a certain electric power, the IC starts over load operation. G: If the setting over load status lasts for T FOLP1 (128ms typ), switching is turned OFF. H: When the VCC pin voltage becomes less than VCHG1, recharge operation is started. I: When the VCC pin voltage becomes more than VCHG2, recharge operation is stopped. J: After TFOLP2 (512ms typ), the over load protection circuit starts switching. K: Same as G www.rohm.com © 2017 ROHM Co., Ltd. All rights reserved. 7/21
SZ02201-0F1F0A200260-1-2
TSZ22111・15・001
17.Apr.2017.Rev.002
Document Outline BM2P135TF_BM2P137TKF_BM2P139TF_BM2P129PF(E)_verB Notice-PGA-E