Datasheet BM2P139TF, BM2P135TF, BM2P137TKF, BM2P129TF (Rohm) - 10
| Manufacturer | Rohm |
| Description | PWM type DC/DC converter IC Integrated Switching MOSFET for non-Isolated type |
| Pages / Page | 24 / 10 — BM2P139TF/BM2P135TF/BM2P137TKF/BM2P129TF. (5) VCC pin protection … |
| File Format / Size | PDF / 1.1 Mb |
| Document Language | English |
BM2P139TF/BM2P135TF/BM2P137TKF/BM2P129TF. (5) VCC pin protection function. (5-1) VCC UVLO / VCC OVP function
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Text Version of Document
BM2P139TF/BM2P135TF/BM2P137TKF/BM2P129TF
Datasheet Datasheet
(5) VCC pin protection function
This IC has the internal protection function at the VCC pin shown in below. 1) Under voltage protection function UVLO (Under Voltage Locked Out) 2) Over voltage protection function VCC OVP (Over Voltage Protection) 3) VCC recharge function
(5-1) VCC UVLO / VCC OVP function
VCC UVLO function and VCC OVP function are auto recovery type comparators that have voltage hysteresis. VCC OVP has an internal mask time. If the condition that the VCC pin voltage is higher than VOVP1 lasts for TCOMP (100us typ), it performs detection. The recovery requirements are that the VCC pin voltage is lower than VOVP2.
(5-2)VCC recharge function
If the VCC pin drops to VCHG1 after once the VCC pin becomes more than VUVLO1 and the IC starts to operate, the VCC charge function operates. At that time, the VCC pin is charged from DRAIN pin through start circuit. When the VCC pin voltage raises to VCHG2 or above, charge is stopped. DRAIN VOVP1 V V CNT OVP2 100us VUVLO1 VCHG2 VUVLO2 VCHG1 VCC VOUT ON ON VCC UVLO ON VCC OVP VCC Recharge Function ON ON SWITCHING A B C D E F G H I J Figure 7. VCC UVLO / VCC OVP / VCC Recharge Function timing chart A: Input voltage is applied to the DRAIN pin and the VCC pin voltage rises. B: When the VCC pin voltage becomes higher than VUVLO1 , the IC starts operating. 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: When the VCC pin voltage becomes higher than VOVP1 , VCC OVP timer operates. D: When the condition that the VCC pin voltage is higher than VOVP1 lasts for TCOMP (100us typ), the IC detects VCC OVP and stops switching. E: When the VCC pin voltage becomes lower than VOVP2, VCC OVP is released. F: When the input power supply is turned OFF, the DRAIN pin voltage drops. G: When the VCC pin voltage becomes less than VCHG1, recharge function is started. H: When the VCC pin voltage becomes higher than VCHG2 , recharge function is stopped. I: When the VCC pin voltage becomes lower than VCHG1, recharge function is started. However the supply to the VCC pin decrease and the VCC pin voltage drops because of low DRAIN voltage. J: When the VCC pin voltage becomes lower than VUVLO2, VCC UVLO function starts operating. www.rohm.com © 2017 ROHM Co., Ltd. All rights reserved. 10/21
SZ02201-0F1F0A200260-1-2
TSZ22111・15・001
17.Apr.2017.Rev.002
Document Outline BM2P135TF_BM2P137TKF_BM2P139TF_BM2P129PF(E)_verB Notice-PGA-E
Datasheet Datasheet
(5) VCC pin protection function
This IC has the internal protection function at the VCC pin shown in below. 1) Under voltage protection function UVLO (Under Voltage Locked Out) 2) Over voltage protection function VCC OVP (Over Voltage Protection) 3) VCC recharge function
(5-1) VCC UVLO / VCC OVP function
VCC UVLO function and VCC OVP function are auto recovery type comparators that have voltage hysteresis. VCC OVP has an internal mask time. If the condition that the VCC pin voltage is higher than VOVP1 lasts for TCOMP (100us typ), it performs detection. The recovery requirements are that the VCC pin voltage is lower than VOVP2.
(5-2)VCC recharge function
If the VCC pin drops to VCHG1 after once the VCC pin becomes more than VUVLO1 and the IC starts to operate, the VCC charge function operates. At that time, the VCC pin is charged from DRAIN pin through start circuit. When the VCC pin voltage raises to VCHG2 or above, charge is stopped. DRAIN VOVP1 V V CNT OVP2 100us VUVLO1 VCHG2 VUVLO2 VCHG1 VCC VOUT ON ON VCC UVLO ON VCC OVP VCC Recharge Function ON ON SWITCHING A B C D E F G H I J Figure 7. VCC UVLO / VCC OVP / VCC Recharge Function timing chart A: Input voltage is applied to the DRAIN pin and the VCC pin voltage rises. B: When the VCC pin voltage becomes higher than VUVLO1 , the IC starts operating. 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: When the VCC pin voltage becomes higher than VOVP1 , VCC OVP timer operates. D: When the condition that the VCC pin voltage is higher than VOVP1 lasts for TCOMP (100us typ), the IC detects VCC OVP and stops switching. E: When the VCC pin voltage becomes lower than VOVP2, VCC OVP is released. F: When the input power supply is turned OFF, the DRAIN pin voltage drops. G: When the VCC pin voltage becomes less than VCHG1, recharge function is started. H: When the VCC pin voltage becomes higher than VCHG2 , recharge function is stopped. I: When the VCC pin voltage becomes lower than VCHG1, recharge function is started. However the supply to the VCC pin decrease and the VCC pin voltage drops because of low DRAIN voltage. J: When the VCC pin voltage becomes lower than VUVLO2, VCC UVLO function starts operating. www.rohm.com © 2017 ROHM Co., Ltd. All rights reserved. 10/21
SZ02201-0F1F0A200260-1-2
TSZ22111・15・001
17.Apr.2017.Rev.002
Document Outline BM2P135TF_BM2P137TKF_BM2P139TF_BM2P129PF(E)_verB Notice-PGA-E
