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FUJITSU SEMICONDUCTOR DATA SHEET
DS04-27212-2E
ASSP For Power Supply Applications
BIPOLAR
Switching Regulator Controller
(Low Voltage)
MB3800
s DESCRIPTION
The MB3800 is a single-channel switching regulator control IC for low voltage applications incorporating a soft start function and short circuit detection function. The device has a low minimum operating voltage of 1.8 V and is ideal for the power supply of battery-operated electronic equipment.
s FEATURES
* * * * * * * * * Wide supply voltage operating range: 1.8 to 15 V Low current consumption: Typically 5.5 mA in operation, 1 A or less in stand-by High speed operation is possible: Maximum 1 MHz The error amplifier gain is set inside the IC, so peripheral components are minimized. Incorporates a soft start circuit. Incorporates a timer-latch type short circuit detection circuit (SCP). Totem-pole type output with adjustable on/off current (for NPN transistors) Incorporates a stand-by function. Three types of packages (SOP-8 or SOL-8, SSOP-8)
s PACKAGES
8-pin Plastic SOP 8-pin Plastic SOL 8-pin Plastic SSOP
(FPT-8P-M01
(FPT-8P-M02)
(FPT-8P-M03)
MB3800
s PIN ASSIGNMENT
(TOP VIEW)
-IN
1
8
FB
SCP
2
7
OSC
V CC
3
6
GND
BR/CTL
4
5
OUT
(FPT-8P-M01) (FPT-8P-M02) (FPT-8P-M03)
s PIN DESCRIPTION
Pin No. 1 2 3 4 5 6 7 8 Symbol -IN SCP VCC BR/CTL OUT GND OSC FB I/O I -- -- I O -- -- O Description Error amplifier inverting input pin Soft start and SCP setting capacitor connection pin Power supply pin Output current setting and control pin Totem-pole type output pin Ground pin Capacitor and resistor connection pin for setting the oscillation frequency Error amplifier output pin
2
MB3800
s BLOCK DIAGRAM
V CC 3
OSC 7
Reference voltage supply
0.6 V- 0.1 V-
Sawtooth wave oscillator OUT 5 0.1 V PWM
1.25 V -IN 1
-
36 k
- Comp.
30 k Output drive control circuit 0.3 V
Error Amp. 0.5 V 500 FB 8
+
+ + +
DTC 0.6 V
Soft start SCP
6 GND
2 SCP
4 BR/CTL
(8 pin)
3
MB3800
s ABSOLUTE MAXIMUM RATINGS
(Ta = +25C) Parameter Power supply voltage Output source current Output sink current Allowable dissipation Operating temperature Storage temperature Symbol VCC IO
+
Condition
Rated Value Min. -- -- -- Max. 16 -50 50 570* 430* 580* +85 +125
Unit V mA mA mW mW mW C C
-- SOP-8, Ta +25C
IO- PD Top Tstg SOP-8, Ta +25C SSOP-8, Ta +25C --
-- -- -- -30 -55
* : When mounted on a 10 cm square double-sided epoxy board WARNING: Semiconductor devices can be permanently damaged by application of stress (voltage, current, temperature, etc.) in excess of absolute maximum ratings. Do not exceed these ratings.
s RECOMMENDED OPERATING CONDITIONS
(Ta = +25C) Parameter Power supply voltage Error amplifier input voltage BR/CTL pin input voltage Output source current Output sink current SCP pin capacitance Phase compensation capacitance Output current setting resistance Timing resistance Timing capacitance Oscillation frequency Operating temperature Symbol VCC VI VBR IO+ IO
-
Values Min. 1.8 -0.2 -0.2 -40 -- -- -- 150 1.0 100 10 -30 Typ. -- -- -- -- -- 0.1 0.1 390 3.0 270 500 +25 Max. 15 1.0 VCC -- 40 -- -- 5000 10.0 10000 1000 +85
Unit V V V mA mA F F k pF kHz C
CPE CP RB RT CT fOSC TOP
WARNING: Recommended operating conditions are normal operating ranges for the semiconductor device. All the device's electrical characteristics are warranted when operated within these ranges. Always use semiconductor devices within the recommended operating conditions. Operation outside these ranges may adversely affect reliability and could result in device failure. No warranty is made with respect to uses, operating conditions, or combinations not represented on the data sheet. Users considering application outside the listed conditions are advised to contact their FUJITSU representative beforehand.
4
MB3800
s ELECTRICAL CHARACTERISTICS
(VCC = +2 V, Ta = +25C) Parameter Circuit to prevent malfunction at low input voltage (U.V.L.O.) Soft start Short circuit detection (S.C.P .) Reset voltage Threshold voltage Charging current Voltage at soft start completion Charging current Threshold voltage Oscillation frequency Sawtooth wave oscillator (OSC) Frequency input stability Frequency variation with temperature Input threshold voltage VT input stability VT variation with temperature Input bias current Error amplifier Voltage gain Frequency bandwidth Maximum output voltage range Output source current Output sink current Idle period adjustment section Maximum duty cycle Symbol VR -- VTH ICS VtS ICPC VtPC fOCS fdV fdT VT VTdV VTdT IB AV BW VOM+ VOM- IOM
+
Condition
Value Min. -- 1.1 Typ. Max. -- 1.3 -1.0 0.8 -1.0 0.8 500 2 5 500 5 1 -0.2 100 6 0.87 0.05 -40 40 75 0.9 1.5 -0.7 0.9 -0.7 0.9 600 10 -- 520 20 -- 1.0 145 -- -- 0.2 -24 -- 85
Unit V V A V A V kHz % % mV mV % A V/V MHz V V A A %
VSCP = 0 V -- VSCP = 0 V -- RT = 3.0 k, CT = 270 pF VCC = 2 V to 15 V Ta = -30C to +85C VFB = 450 mV VCC = 2 V to 15 V Ta = -30C to +85C VIN = 0 V -- AV = 0 dB --
-1.5 0.7 -1.5 0.7 400 -- -- 480 -- -- -1.0 70 -- 0.78 -- -- 24 65
IOM- tDUTY
VFB = 0.45 V RT = 3.0 k, CT = 270 pF VFB = 0.8 V
(Continued)
5
MB3800
(Continued)
Parameter Symbol VOH1 VOH2 Output voltage Output section Output source current Output sink current Pull down resistance Pin voltage Output current setting section/ Control section Input off condition Input on condition Pin current range Stand-by current Entire device Average supply current VOL1 VOL2 IO+ IO- RO VBR IOFF ION IBR ICCS ICC BR/CTL pin open or VCC RB = 390 -- RB = 390 Condition RB = 390 , IO = -15 mA RB = 750 , VCC = 1.8 V IO = -10 mA RB = 390 , IO = 15 mA RB = 750 , VCC = 1.8 V IO = 10 mA RB = 390 , VO = 0.9 V RB = 390 , VO = 0.3 V -- Value Min. 1.0 0.8 -- -- -- 30 20 0.2 -20 -- -1.8 -- -- Typ. Max. 1.2 1.0 0.1 0.1 -30 60 30 0.3 -- -- -- -- 5.5 -- -- 0.2 0.2 -20 -- 40 0.4 0 -45 -0.1 1 9.3 Unit V V V V mA mA k V A A mA A mA
s DIAGRAM
FB pin voltage Reference input for short circuit detection comparator Idle period setting voltage Sawtooth wave output Soft start setting voltage
OUT pin waveforms
SCP pin waveforms t PE Output short circuit
Soft start tS ON Power supply control SW OFF
Output short circuit
Short circuit detection
6
MB3800
s HOW TO SET THE TIME CONSTANT FOR SOFT START AND SHORT CIRCUIT DETECTION
1. Soft Start
At power on, the capacitor CPE connected to the SCP pin starts charging. The PWM comparator compares the soft start setting voltage as a proportion of the voltage at the SCP pin with the sawtooth waveform. The comparison controls the ON duty of the OUT pin, causing the soft start operation. On completion of soft start operation, the voltage at the SCP pin stays low, the soft start setting voltage stays high, and the circuit enters the output short circuit detection wait state. Soft start time (The time until the output ON duty reaches approximately 50%) tS [s] 0.35 x CPE [F]
2. Short Circuit Protection
If the switching regulator output suddenly drops due to load effect, the error amplifier output (FB pin) is fixed at VOM+ and capacitor CPE starts charging. When the voltage at the SCP pin reaches approximately 0.8V, the output pin is set low and the SCP pin stays low. Once the protection circuit operates, the circuit can be restored by resetting the power supply. * Short circuit detection time tPE [s] 0.8 x CPE [F]
7
MB3800
s TYPICAL CHARACTERISTICS
Supply voltage vs. Supply current 10 Supply current I CC (mA) 8 6 4 2 0 T a = +25C R B = 390 1.0 Input threshold voltage V T (V) 0.8 0.6 0.4 0.2 0 Supply voltage vs. Input threshold voltage T a = +25C
0
4
8
12
16
20
0
4
8
12
16
20
Supply voltage V CC (V)
Supply voltage V CC (V)
Input threshold voltage variation ratio V T/V T (%)
Ambient temperature vs. Input threshold voltage variation ratio 10 V CC = 2 V 5
Supply voltage vs. Input threshold voltage 1.0 Input threshold voltage V T (V) 0.8 0.6 0.4 0.2 0 T a = +25C
0
-5
-10
0
1.0
2.0
3.0
4.0
5.0
-15 -40
-20
0
20
40
60
80
100
Supply voltage V CC (V)
Ambient temperature T a (C)
High level output Low level output voltage V OUT (mV) High level output voltage V OUT (V) 2.0 1.6 1.2 0.8 0.4 0 V CC = 2 V R B = 390 T a = +25C 500 400 300 200 100 0
Low level output V CC = 2 V R B = 390 T a = +25C
0
-10
-20
-30
-40
-50
0
20
40
60
80
100
High level output current I OUT (mA)
High level output current I OUT (mA)
(Continued)
8
MB3800
(Continued)
BR/CTL pin current vs. Output source current -50 -40 -30 -20 -10 0 V CC = 2 V V OUT = 0.9 V T a = +25C 500 BR/CTL pin current vs. BR/CTL pin voltage
Output source current I OUT (mA)
BR/CTL pin voltage V BR (mV)
400 300 200 100 0
V CC = 2 V T a = +25C
0
-0.4
-0.8
-1.2
-1.6
-2.0
0
-0.4
-0.8
-1.2
-1.6
-2.0
BR/CTL pin current I BR (mA)
BR/CTL pin current I BR (mA) Timing resistor vs. Oscillation frequency
BR/CTL pin current vs. Supply current 1M 5.0 C T = 100 pF 500 k 200 k 100 k 50 k 20 k 10 k 5k 2k 1k 2k 5k C T = 10000 pF C T = 1000 pF
V CC = 2 V T a = +25C
4.0 3.0 2.0 1.0 0
Oscillation frequency f OSC (Hz)
Supply current I CC (mA)
V CC = 2 V T a = +25C
0
-20
-40
-60
-80
-100
10 k
20 k
BR/CTL pin current I BR (A)
Timing resistor R T ()
Supply voltage vs. Frequency variation ratio 10 10
Ambient temperature vs. Frequency variation ratio V CC = 2 V C T = 270 pF R T = 3.0 k
Frequency variation ratio f/f (%)
5
Frequency variation ratio f/f (%)
16
C T = 270 pF R T = 3.0 k Ta = +25C
5
0
0
-5
-5
-10
-10
-15
0
2
4
6
8
10
12
14
-15 -40
-20
0
20
40
60
80
100
Supply voltage V CC (V)
Ambient temperature T a (C)
(Continued)
9
MB3800
(Continued)
Oscillation frequency vs. Maximum duty cycle 100 V CC = 2 V C T = 270 pF Ta = +25C
Maximum duty cycle t DUTY (%)
80 60 40 20 0 10 K
100 K Oscillation frequency f OSC (Hz)
1M
Output pin voltage and current waveforms (reference data)
(V) 6 4 V OUT 2 0 (mA) 50 I OUT 0 -50 10 mV 0 0.4 0.8 1.2 200 ns 1.6 2.0 t (s) 2V V CC = 2 V C T = 270 pF R T = 1.0 k
Note: The OFF delay time of V OUT depends on the characteristics of the external transistor.
Measurement circuit diagram
V CC 22 H (5 V)
18 k MB3800 5 I OUT V OUT 10 F
4 2 k 390
-IN
10
MB3800
s FUNCTIONAL DESCRIPTION
1. Switching Regulator Function
(1) Reference voltage circuit The reference voltage circuit generates a temperature-compensated reference voltage (1.25V) from voltage supplied from the power supply pin (pin 3). In addition to providing the reference voltage for the switching regulator, the circuit also sets the idle period. (2) Sawtooth wave oscillator The sawtooth oscillator generates a sawtooth wave (up to 1 MHz) that is stable with respect to the supply voltage and temperature. The capacitor and resistor that set the oscillation frequency are connected to the OSC pin (pin 7). (3) Error amplifier (Error Amp.) The error amplifier detects the output voltage of the switching regulator and outputs the PWM control signal. The voltage gain is fixed, and connecting a phase compensation capacitor to the FB pin (pin 8) provides stable phase compensation for the system. (4) PWM comparator (PWM Comp.) The voltage comparator has one inverting and three non-inverting inputs. The comparator is a voltage/pulse width converter that controls the ON time of the output pulse depending on the input voltage. The output level is high (H) when the sawtooth wave is lower than the error amplifier output voltage, soft start setting voltage, and idle period setting voltage. (5) Output circuit The output circuit has a totem pole type configuration and can drive an external NPN transistor directly. The value of the ON/OFF current can be set by a resistor connected to the BR/CTL pin (pin 4).
2. Power Supply Control Function
Stand-by mode (supply current 1 A or less) can be set by connecting the BR/CTL pin (pin 4) to VCC or by making the pin open circuit. SW OFF ON Mode Stand-by mode Operating mode
MB3800
4 BR/CTL
RB
SW
11
MB3800
3. Other Functions
(1) Soft start and short circuit detection Soft start operation is set by connecting capacitor CPE to the SCP pin (pin 2). Soft start prevents a current spike on start-up. On completion of soft start operation, the SCP pin (pin 2) stays low and enters the short circuit detection wait state. When an output short circuit occurs, the error amplifier output is fixed at VOM+ and capacitor CPE starts charging. After charging to approximately 0.8 V, the output pin (pin 5) is set low and the SCP pin (pin 2) stays low. Once the protection circuit operates, the circuit can be restored by resetting the power supply. (See "s HOW TO SET THE TIME CONSTANT FOR SOFT START AND SHORT CIRCUIT DETECTION".) (2) Circuit to prevent malfunction at low input voltage Transients when powering on or instantaneous glitches in the supply voltage can lead to malfunction of the control IC and cause system damage or failure. The circuit to prevent malfunction at low input voltage detects a low input voltage by comparing the supply voltage to the internal reference voltage. On detection, the circuit fixes the output pin to low. The system recovers when the supply voltage rises back above the threshold voltage of the malfunction prevention circuit.
s APPLICATION EXAMPLE
18 k 22 H
Vo (5 V)
-IN SCP V in (3 V) V CC 33 F
1 2 MB3800 3
8 7 6 5
FB OSC GND OUT 10 F
BR/CTL 4 0.1 F 2 k 390
270 pF 3 k
0.1 F
CTL
12
MB3800
s USAGE PRECAUTIONS
1. Do not apply an input voltage greater than the maximum rating.
Do not input voltages greater than the maximum rating as this can cause damage to the LSI.
2. Use in accordance with the recommended operating conditions.
The electrical characteristics of the LSI are not guaranteed if the input voltage is greater than the maximum. Also, LSI operation is unstable if the input voltage is less than the minimum. Therefore, always use in accordance with the recommended operating conditions.
3. Use a wide ground line on the printed circuit board.
As the LSI uses a high frequency and therefore can generate high frequency noise, make the ground line as wide as possible.
4. Take anti-static precautions.
* Use a holder for inserting the semiconductor which is anti-static or conductive. * After mounting the device on a printed circuit board, store or transport the board in a conductive bag or container. * Earth work benches, tools, and measuring equipment. * Ensure that maintenance personnel have a resistance of 250 k to 1 M in series between their body and earth.
13
MB3800
s ORDERING INFORMATION
Part number MB3800PF MB3800PNF MB3800PFV Package 8-pin Plastic SOP (FPT-8P-M01) 8-pin Plastic SOL (FPT-8P-M02) 8-pin Plastic SSOP (FPT-8P-M03) Remarks
14
MB3800
s PACKAGE DIMENSIONS
8-pin Plastic SOP (FPT-8P-M01)
2.25(.089)MAX 6.35
+0.25 -0.20
.250
+.010 -.008
0.05(.002)MIN (STAND OFF)
INDEX
5.300.30 (.209.012)
7.800.40 (.307.016)
6.80 -0.20 +.016 .268 -.008
+0.40
1.27(.050) TYP 3.81(.150)REF
0.450.10 (.018.004)
O0.13(.005)
M
0.15 -0.02 +.002 .006 -.001
+0.05
0.500.20 (.020.008)
Details of "A" part 0.20(.008)
0.50(.020) "A" 0.10(.004) 0.18(.007)MAX 0.68(.027)MAX
C
1994 FUJITSU LIMITED F08002S-4C-4
Dimensions in mm (inches).
(Continued)
15
MB3800
(Continued)
8-pin Plastic SOL (FPT-8P-M02)
5.05 -0.20 .199 -.008
+0.25
+.010
1.550.20(.061.008)
0.150.10 (STAND OFF) (.006.004) 3.900.30 (.154.012) 6.000.40 (.236.016) 45 5.000.30 (.197.012)
0.40(.016) 1.27(.050)TYP 0.420.10 (.017.004) O0.13(.005)
M
0.200.05 (.008.002) Details of "A" part
0.50.020 (.020.008)
0.40(.016)
"A" 3.81(.150)REF
0.10(.004)
0.20(.008) 0.18(.007)MAX 0.65(.026)MAX
C
1994 FUJITSU LIMITED F08004S-2C-4
Dimensions in mm (inches).
16
MB3800
(Continued)
8-pin Plastic SSOP (FPT-8P-M03)
* 3.500.10
(.138.004)
1.25 -0.10 +.008 .049 -.004
+0.20
0.10(.004)
INDEX
4.200.10 (.165.004)
5.20(.205) NOM
6.200.20 (.244.008)
"A"
0.80(.0315) TYP
0.350.10 (.014.004)
0.10(.004)
M
0.15 -0.02 +.002 .006 -.001
+0.05
Details of "A" part 0.100.10(.004.004) (STAND OFF)
2.40(.094)REF
0
10
0.500.20 (.020.008)
C
1994 FUJITSU LIMITED F08005S-1C-2
Dimensions in mm (inches).
17
MB3800
FUJITSU LIMITED
For further information please contact:
Japan FUJITSU LIMITED Corporate Global Business Support Division Electronic Devices KAWASAKI PLANT, 4-1-1, Kamikodanaka Nakahara-ku, Kawasaki-shi Kanagawa 211-8588, Japan Tel: (044) 754-3763 Fax: (044) 754-3329
All Rights Reserved. The contents of this document are subject to change without notice. Customers are advised to consult with FUJITSU sales representatives before ordering. The information and circuit diagrams in this document presented as examples of semiconductor device applications, and are not intended to be incorporated in devices for actual use. Also, FUJITSU is unable to assume responsibility for infringement of any patent rights or other rights of third parties arising from the use of this information or circuit diagrams. FUJITSU semiconductor devices are intended for use in standard applications (computers, office automation and other office equipment, industrial, communications, and measurement equipment, personal or household devices, etc.). CAUTION: Customers considering the use of our products in special applications where failure or abnormal operation may directly affect human lives or cause physical injury or property damage, or where extremely high levels of reliability are demanded (such as aerospace systems, atomic energy controls, sea floor repeaters, vehicle operating controls, medical devices for life support, etc.) are requested to consult with FUJITSU sales representatives before such use. The company will not be responsible for damages arising from such use without prior approval. Any semiconductor devices have inherently a certain rate of failure. You must protect against injury, damage or loss from such failures by incorporating safety design measures into your facility and equipment such as redundancy, fire protection, and prevention of over-current levels and other abnormal operating conditions. If any products described in this document represent goods or technologies subject to certain restrictions on export under the Foreign Exchange and Foreign Trade Control Law of Japan, the prior authorization by Japanese government should be required for export of those products from Japan.
http://www.fujitsu.co.jp/
North and South America FUJITSU MICROELECTRONICS, INC. Semiconductor Division 3545 North First Street San Jose, CA 95134-1804, USA Tel: (408) 922-9000 Fax: (408) 922-9179 Customer Response Center Mon. - Fri.: 7 am - 5 pm (PST) Tel: (800) 866-8608 Fax: (408) 922-9179
http://www.fujitsumicro.com/
Europe FUJITSU MIKROELEKTRONIK GmbH Am Siebenstein 6-10 D-63303 Dreieich-Buchschlag Germany Tel: (06103) 690-0 Fax: (06103) 690-122
http://www.fujitsu-ede.com/
Asia Pacific FUJITSU MICROELECTRONICS ASIA PTE LTD #05-08, 151 Lorong Chuan New Tech Park Singapore 556741 Tel: (65) 281-0770 Fax: (65) 281-0220
http://www.fmap.com.sg/
F9802 (c) FUJITSU LIMITED Printed in Japan
18

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