DatasheeDatasheett 0.65V to 5.5V, 1ch Ultra Low Dropout Line ar Regulator Controller BD3504FVM General Description Key Specifications BD3504FVM is an ultra-low dropout linear regulator Drain Voltage Range: 0.65V to 5.5V controller for chipset that can achieve ultra-low input to Supply Voltage Range: 4.5V to 5.5V output voltage. By using N-MOSFET for external power Output Voltage Range: 0.65V to 2.5V transistor, the controller can be used at ultra-low I/O External FET GATE Drive Current: 3mA(Typ) voltage difference as low as the voltage generated by Standby Current: 0A (Typ) ON-Resistance. By reducing the I/O voltage difference, Operating Temperature Range: -10C to +100C large output current is achieved and conversion loss can be reduced, thus the controller can be used in Package W(Typ) x D(Typ) x H(Max) replacement of a switching power supply. In addition, downsizing and cost reduction of the set can be achieved as suitable power transistor can be selected depending on the output current. BD3504FVM does not need any choke coil, diode for rectification and power transistor which are all necessary in a switching power supply, thus reduced total cost and compact size can be achieved for the set. Using external resistors, output voltage ranging from 0.65V to 2.5V can be selected. It is also possible to meet the power supply sequence of the set since output voltage start-up time can be adjusted by using the NRCS terminal. MSOP8 2.90mm x 4.00mm x 0.90mm Features Reduced rush current by NRCS Built-in driver for external Nch transistor Applications Built-in timer latch short protection circuit Mobile PC, desktop PC, digital home appliances Built-in under voltage lock out circuit Output voltage variable type Built-in thermal shutdown circuit Typical Application Circuit and Block Diagram VCC VCC 4 R2 VD R2 IN VIN UVLO2 88 VD UVLO R1 UVLO1 R1 UVLO1 VREF EN Enable LATCH Reference EN 3 Block G NRCS 7 0.65V OUT Vo 0.65V TSD VS 6 SCP UVLO1 R2 R UVLO2 2 EN Thermal VFB 5 Protection SCP RR1 1 TSD 0.65V SCP NRCS NRCS 1 2 NRCS GND Product structureSilicon monolithic integrated circuit This product has no designed protection against radioactive rays .w ww.rohm.com TSZ02201-0J2J0A601070-1-2 2015 ROHM Co., Ltd. All rights reserved. 1/17 TSZ2211114001 02.Nov.2015 Rev.001 BD3504FVM Pin Configuration Pin Descriptions Pin Pin Pin Function No. Name TOP VIEW NRCS (Non Rush Current on Start up) time setup. Timer latch setup for Short Circuit 1 NRCS Protection operating time set up Pin. 8 NRCS 1 VD Ground pin 2 GND 3 EN Enable pin 7 2 G GND Power source 4 VCC Output voltage feedback 5 VFB 6 3 EN VS Source voltage pin 6 VS MOSFET driver output 7 G 4 5 Drain voltage sense VCC VFB 8 VD Description of Operations 1. VCC BD3504FVM has an independent power input pin for the internal circuit operation of the IC. This is used to bias the IC internal circuit and external N-Channel MOSFET. The voltage used for VCC terminal is 5.0V and maximum current is 1.7mA. It is recommended to connect a bypass capacitor with a value of 1F or more to VCC pin. 2. EN With an input of 2.0V or higher, the EN terminal turns to High level and OUT is produced. At 0.8V or lower, it detects Low level and OUT is turned OFF. Simultaneously, the discharge circuit inside the VS terminal is activated and output voltage is reduced (150 mA (Min) when V =1V and V =0V). VS EN 3. VD The VD terminal is the drain voltage detection terminal of the external N-Channel MOSFET. When drain voltage (IN) is low, output voltage is turned OFF to prevent under voltage lock out. The reset voltage (VDUVLO) of under voltage lock out circuit is determined by the following equation: R R 1 2 V V 0.7 VDUVLO IN R 1 At low-input drain voltage, when UVLO resistors have resistance values same as output voltage resistors (R1 = R1, R2 = R2), under voltage lock out (UVLO) is reset when drain voltage (IN) reaches 70% of the output voltage. UVLO detects only at the startup of the EN terminal. 4. VFB The VFB terminal is use to decide the output voltage and is determined by the following equation: R R 1 2 V V OUT VFB R 1 where: V is controlled to achieve 0.65 V (typ). VFB 5. NRCS terminal The NRCS terminal is a constant current output terminal, and operates as Soft-Start ... during start-up SCP-Delay ... after start-up How to set Soft-Start of NRCS terminal The output voltage startup time (tNRCS) is determined by the time when the NRCS terminal reaches VVFB (0.65V). During start-up, the NRCS terminal serves as a constant current source (I ) of 20 A (Typ) output, and charges NRCS externally connected capacitor (C ). Output voltage (V ) becomes stable when NRCS terminal reaches the NRCS OUT internal reference voltage (0.65V). How to set NRCS terminal short protection Delay BD3504FVM has short circuit protection (SCP) which is activated when output voltage becomes VOUT x 0.35 (typ) or lower. The time when SCP is activated until latch takes place (tSCP) is determined by the following equation: t C V I SCP NRCS OSCP SCP When SCP is activated, the NRCS terminal provides 20 A (typ) constant current output (lSCP), and charges the externally connected capacitor (CNRCS). When the NRCS terminal reaches 1.3V (VOSCP), latch operation is carried out and output voltage is turned OFF. www.rohm.com TSZ02201-0J2J0A601070-1-2 2015 ROHM Co., Ltd. All rights reserved. 2/17 TSZ2211115001 02.Nov.2015 Rev.001