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Single-chip Type with built-in FET Switching Regulator Series

Flexible Step-down

Switching Regulators

with Built-in Power MOSFET

BD9778F, BD9778HFP, BD9001F, BD9781HFP

Rcaflga_jLmrc

Rca

lga_



2010.02 -

Rev. B

www.rohm.com

No.10027EBT41

Overview

Features

10)

11)

12)

13)

14)

15)

Minimal external components

Wide input voltage range: 7 V to 35 V (BD9778F/HFP and BD9781HFP), 7 V to 48 V (BD9001F)

Built-in P-ch POWER MOS FET

Output voltage setting enabled with external resistor: 1 to V

Reference voltage accuracy: ±2%

Wide operating temperature range: -40˚C to +125˚C (BD9778F/HFP and BD9781HFP),

-40˚C to +95˚C (BD9001F)

Low dropout: 100% ON Duty cycle

Standby mode supply current: 0 µA (Typ.) (BD9778F/HFP and BD9781HFP), 4 µA (Typ.) (BD9001F)

Oscillation frequency variable with external resistor: 50 to 300 kHz (BD9001F),

50 to 500 kHz (BD9778F/HFP and BD9781HFP)

External synchronization enabled (only on the BD9781HFP)

Soft start function : soft start time fixed to 5 ms (Typ.))

Built-in overcurrent protection circuit

Built-in thermal shutdown protection circuit

High power HRP7 package mounted (BD9778HFP and BD9781HFP)

Compact SOP8 package mounted (BD9778F and BD9001F)

All fields of industrial equipment, such as Flat TV , printer, DVD, car audio, car navigation,

and communication such as ETC, AV, and OA.

Applications

Product lineup

The flexible step-down switching regulator controller is a switching regulator controller designed with a high-withstand-voltage

built-in POWER MOS FET, providing a free setting function of operating frequency with external resistor. This switching regulator

controller features a wide input voltage range (7 V to 35 V or 7 V to 48 V) and operating temperature range (-40˚C to +125˚C or

-40˚C to +95˚C). Furthermore, an external synchronization input pin (BD9781HFP) enables synchronous operation with external

clock.

BD9778F/HFP

7V ~ 35V

50 ~ 500kHz

Not provided

Provided

40˚C ~ +125˚C

SOP8 / HRP7

Output current

Input range

Oscillation frequency range

External synchronization

Standby function

Operating temperature

Package

BD9001F

7V ~ 48V

50 ~ 300kHz

Not provided

Provided

40˚C ~ +95˚C

SOP8

BD9781HFP

7V ~ 35V

50 ~ 500kHz

Provided

40˚C ~ +125˚C

HRP7

Item

Summary of content (17 pages)

PAGE 1
Rcaflga_j Lmrc R caflga_j L Single-chip Type with built-in FET Switching Regulator Series Flexible Step-down Switching Regulators with Built-in Power MOSFET BD9778F, BD9778HFP, BD9001F, BD9781HFP No.10027EBT41 Overview The flexible step-down switching regulator controller is a switching regulator controller designed with a high-withstand-voltage built-in POWER MOS FET, providing a free setting function of operating frequency with external resistor.
PAGE 2
Technical Note BD9778F, BD9778HFP, BD9001F, BD9781HFP Absolute Maximum Ratings(Ta = 25˚C) Parameter BD9778F/HFP,BD9781HFP Power supply BD9001F voltage Output switch pin voltage Output switch current Limits 36 50 VIN 2 4 VIN 7 5.5 0.
PAGE 3
Technical Note BD9778F, BD9778HFP, BD9001F, BD9781HFP BD9001F (Unless otherwise specified, Ta=-40˚C ~ +95˚C,VIN=13.
PAGE 4
Technical Note BD9778F, BD9778HFP, BD9001F, BD9781HFP Reference data 1.010 1.005 1.000 0.995 0.990 0.985 -25 0 25 50 75 100 10 39kΩ 500 400 91kΩ 300 200 390kΩ 100 910kΩ 0 -50 125 AMBIENT TEMPERATURE : Ta[Ŋ] 25 50 7 6 125Ŋ 5 VCC=12V Istb=0.14µA 4 3 2 1 0 100 125 75 25Ŋ 0 5 10 15 20 25 -40Ŋ 30 35 40 INPUT VOLTAGE : VIN[V] Fig.2 Frequency vs. Ambient temperature(All series) Fig.
PAGE 5
Technical Note 1.8 1.6 1.6 1.6 1.2 1.0 0.8 Ta=125Ŋ 0.6 Ta=25Ŋ Ta=-40Ŋ 0.4 0.2 0.0 0.0 0.5 1.0 1.5 2.0 OUTPUT CURRENT : IO[A] 1.0 0.8 Ta=125Ŋ 0.6 Ta=25Ŋ 0.4 100 1.6 90 1.2 Ta=125Ŋ 1.0 Ta=25Ŋ 0.8 0.6 Ta=–40Ŋ 0.4 0.2 0.0 0.5 1 1.5 2 OUTPUT CURRENT : IO[A] 0.8 Ta=125Ŋ 0.6 Ta=25Ŋ 0.4 Ta=–40Ŋ 0.2 0 80 3.3V output 70 2.5V output 60 50 40 30 20 0.5 1 1.5 2 OUTPUT CURRENT : IO[A] 2.5 Fig.15 ON resistance VIN=7V (BD9001F) 5V output 3.3V output 90 80 70 60 2.5V output 1.
PAGE 6
Technical Note BD9778F, BD9778HFP, BD9001F, BD9781HFP Block diagram / Application circuit / Pin assignment (BD9778F) (BD9778HFP) PVIN 8 EN VIN 220µF 1µF 220µF 23kΩ INV 10kΩ GND EN PVIN RT SW DRIVER 33µH VO 10kΩ 2 RESET TSD OSC - PWM COMPARATOR LATCH + 150kΩ Vref 4700pF + + 5 LATCH + 150kΩ ERROR AMP INV PWM COMPARATOR - Vref SOFT START 23kΩ + + L:OFF H:ON 1µF Vref ERROR AMP 4 7 ON/OFF 1 L:OFF H:ON SOFT START EN VIN 5 ON/OFF 1 4700pF TSD OSC 330µF 330
PAGE 7
BD9778F, BD9778HFP, BD9001F, BD9781HFP Technical Note Description of operations ERROR AMP The ERROR AMP block is an error amplifier used to input the reference voltage (1 V typ.) and the INV pin voltage. The output FB pin controls the switching duty and output voltage Vo. These INV and FB pins are externally mounted to facilitate phase compensation. Inserting a capacitor and resistor between these pins enables adjustment of phase margin. (Refer to recommended examples on page 11.
PAGE 8
Technical Note BD9778F, BD9778HFP, BD9001F, BD9781HFP Timing chart (BD9781HFP) - While in basic operation mode VIN Internal OSC FB SW EN/SYNC Fig.27 - While in overcurrent protection mode IO Internal OSC FB SW Output short circuit Auto reset Auto reset Auto reset Auto reset Fig.28 External synchronizing function (BD9781HFP) In order to activate the external synchronizing function, connect the frequency setting resistor to the RT pin and then input a synchronizing signal to the EN/SYNC pin.
PAGE 9
Technical Note BD9778F, BD9778HFP, BD9001F, BD9781HFP Description of external components L VIN VO SW VIN + C Cin Di CO R1 INV RT RT CT R2 FB SS CC GND RC CSS Fig.30 Design procedure Calculation example Vo = Output voltage, Vin (Max.) = Maximum input voltage Io (Max.) = Maximum load current, f = Oscillation frequency 1. Setting or output voltage Output voltage can be obtained by the formula shown below.
PAGE 10
Technical Note BD9778F, BD9778HFP, BD9001F, BD9781HFP Design procedure Calculation example 4. Selection of diode Set diode rating with an adequate margin to the maximum load current. Also, make setting of the rated inverse voltage with an adequate margin to the maximum input voltage. A diode with a low forward voltage and short reverse recovery time will provide high efficiency. 5.
PAGE 11
Technical Note BD9778F, BD9778HFP, BD9001F, BD9781HFP Cin C Cin Di C Cx2 R2 C3 R3 C3 Co Cx2 R2 RT CT Cx1 Di R1 RT CT Cx1 R3 L L R1 Co Fig.32 BD9001F reference layout pattern Fig.33 BD9781HFP reference layout pattern Ţ As shown above, design the GND pattern as large area as possible within inner layer. Ţ Gray zones indicate GND.
PAGE 12
Technical Note BD9778F, BD9778HFP, BD9001F, BD9781HFP 2. For output capacitors having high ESR, such as electrolyte capacitor For output capacitors that have high ESR (i.e., several Ω), the phase compensation setting procedure becomes comparatively simple. Since the DC/DC converter application has a LC resonant circuit attached to the output, a -180˚ phase-delay occurs in that area. If ESR component is present, howeve r, a +90˚ phase-lead occurs to shift the phase delay to -90˚.
PAGE 13
Technical Note BD9778F, BD9778HFP, BD9001F, BD9781HFP Measurement of open loop of DC/DC converter To measure the open loop of DC/DC converter, r use the gain phase analyzer or FRA A to measure the frequency characteristics. DC/DC converter controller 1. Check to ensure output causes no oscillation at the maximum load in closed loop. 2. Isolate (1) and (2) and insert Vm (with amplitude of approximately 100 mVpp). 3. Measure (probe) the oscillation of (1) to that of (2).
PAGE 14
Technical Note BD9778F, BD9778HFP, BD9001F, BD9781HFP SW RT VIN FB&BD9778F/HFP, BD9781HFP ' VREF VIN INV VREF VREF VIN VIN 50kΩ VIN SW FB INV 10kΩ 1kΩ 1kΩ 300kΩ RT 2kΩ EN&BD9778F/HFP, BD9001F ' FB&BD9001F' EN/SYNC&BD9781HFP' VREF VREGA VIN VIN VIN EN FB 1kΩ 300kΩ 1kΩ 2kΩ EN/SYNC 250kΩ 222 kΩ 221 kΩ 145 kΩ 139 kΩ Fig.
PAGE 15
Technical Note BD9778F, BD9778HFP, BD9001F, BD9781HFP 7) IC pin input (Fig. 37) This monolithic IC contains P+ isolation and P substrate layers between adjacent elements to keep them isolated. P-N junctions are formed at the intersection of these P layers with the N layers of other elements, creating a parasitic diode or transistor. For example, the relation between each potential is as follows: When GND > Pin A and GND > Pin B, the P-N junction operates as a parasitic diode.
PAGE 16
Technical Note BD9778F, BD9778HFP, BD9001F, BD9781HFP Selection of order type B D 9 Part No. 7 7 8 H F - P Package F = SOP8 HFP = HRP7 Part No. 9778 = 36V/2A 9781 = 36V/4A 9001 = 50V/2A T R Taping type E2 = Reel-type embossed carrier tape (SOP8) TR = Reel-type embossed carrier tape (HRP7) SOP8 7 6 5 6.2±0.3 4.4±0.2 0.3MIN 8 +6° 4° −4° 0.9±0.15 5.0±0.2 (MAX 5.
PAGE 17
Notice Notes No copying or reproduction of this document, in part or in whole, is permitted without the consent of ROHM Co.,Ltd. The content specified herein is subject to change for improvement without notice. The content specified herein is for the purpose of introducing ROHM's products (hereinafter "Products"). If you wish to use any such Product, please be sure to refer to the specifications, which can be obtained from ROHM upon request.