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FUJITSU SEMICONDUCTOR DATA SHEET
DS04-27212-3E
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 V 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 : 2 types, SSOP-8 : 1 type)
s PACKAGES
8-pin Plastic SOP 8-pin Plastic SOP 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 Error Amp. 500
- Comp.
+
0.5 V FB 8
+ + +
30 k Output drive control circuit 0.3 V
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
Rating Min -- -- -- Max 16 -50 50 570* 430* 580* +85 +125
Unit V mA mA mW mW mW C C
-- FPT-8P-M01, Ta +25C
IO- PD Top Tstg FPT-8P-M02, 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
+ -
Value 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
IO
CPE CP RB RT CT fOSC TOP
WARNING: The recommended operating conditions are required in order to ensure the normal operation of the semiconductor device. All of the device's electrical characteristics are warranted when the device is operated within these ranges. Always use semiconductor devices within their recommended operating condition ranges. 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 representatives 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
+
Condition
Value Min -- 1.1 Typ -- 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 Max 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
VOM- IOM+ IOM
-
VFB = 0.45 V RT = 3.0 k, CT = 270 pF VFB = 0.8 V
tDUTY
(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 1.2 1.0 0.1 0.1 -30 60 30 0.3 -- -- -- -- 5.5 Max -- -- 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 0.8 V, 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 BR/CTL pin voltage V BR (mV) 500 400 300 200 100 0 BR/CTL pin current vs. BR/CTL pin voltage
Output source current I OUT (mA)
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 Supply current I CC (mA) 4.0 3.0 2.0 1.0 0 Oscillation frequency f OSC (Hz) V CC = 2 V T a = +25C 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 C T = 100 pF
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 Frequency variation ratio f/f (%) Frequency variation ratio f/f (%) C T = 270 pF R T = 3.0 k Ta = +25C 10
Ambient temperature vs. Frequency variation ratio V CC = 2 V C T = 270 pF R T = 3.0 k
5
5
0
0
-5
-5
-10
-10
-15
0
2
4
6
8
10
12
14
16
-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 NOTES ON USE
* Take account of common impedance when designing the earth line on a printed wiring board. * Take measures against static electricity. - For semiconductors, use antistatic or conductive containers. - When storing or carrying a printed circuit board after chip mounting, put it in a conductive bag or container. - The work table, tools and measuring instruments must be grounded. - The worker must put on a grounding device containing 250 k to 1 M resistors in series. * Do not apply a negative voltage - Applying a negative voltage of -0.3 V or less to an LSI may generate a parasitic transistor, resulting in malfunction.
s ORDERING INFORMATION
Part number MB3800PF MB3800PNF MB3800PFV Package 8-pin Plastic SOP (FPT-8P-M01) 8-pin Plastic SOP (FPT-8P-M02) 8-pin Plastic SSOP (FPT-8P-M03) Remarks
13
MB3800
s PACKAGE DIMENSIONS
8-pin Plastic SOP (FPT-8P-M01) Note 1) Note 2) Note 3) Note 4)
+0.25 +.010
*1 : These dimensions include resin protrusion. *2 : These dimensions do not include resin protrusion. Pins width and pins thickness include plating thickness. Pins width do not include tie bar cutting remainder.
0.17 -0.04 .007 -.002
+0.03 +.001
*1 6.35 -0.20 .250 -.008
8
5
INDEX
*2 5.300.30 7.800.40 (.209.012) (.307.016)
Details of "A" part 2.00 -0.15 .079 -.006
1 4
+0.25 +.010
(Mounting height)
"A" 0.13(.005)
0.25(.010) 0~8
1.27(.050)
0.470.08 (.019.003)
M
0.500.20 (.020.008) 0.600.15 (.024.006)
0.10 -0.05
+0.10 +.004
.004 -.002 (Stand off)
0.10(.004)
C
2002 FUJITSU LIMITED F08002S-c-6-7
Dimensions in mm (inches) . Note : The values in parentheses are reference values.
(Continued)
14
MB3800
8-pin Plastic SOP (FPT-8P-M02)
Note 1) Note 2) Note 3) Note 4)
+.010
*1 : These dimensions include resin protrusion. *2 : These dimensions do not include resin protrusion. Pins width and pins thickness include plating thickness. Pins width do not include tie bar cutting remainder.
0.22 -0.07 .009 -.003
+0.03 +.001
*1 5.05 -0.20 .199 -.008
8
+0.25
5
*2 3.900.30 6.000.40 (.154.012) (.236.016)
Details of "A" part 45 1.550.20 (Mounting height) (.061.008) 0.25(.010)
0.40(.016)
1 4
"A"
0~8
1.27(.050)
0.440.08 (.017.003)
0.13(.005)
M
0.500.20 (.020.008) 0.600.15 (.024.006)
0.150.10 (.006.004) (Stand off)
0.10(.004)
C
2002 FUJITSU LIMITED F08004S-c-4-7
Dimensions in mm (inches) . Note : The values in parentheses are reference values.
(Continued)
15
MB3800
(Continued)
8-pin Plastic SSOP (FPT-8P-M03) Note 1) Note 2) Note 3) Note 4) *1 : Resin protrusion. (Each side : +0.15 (.006) Max) . *2 : These dimensions do not include resin protrusion. Pins width and pins thickness include plating thickness. Pins width do not include tie bar cutting remainder.
0.17 -0.04 .007 -.002
+0.03 +.001
*1 3.500.10(.138.004)
8 5
*2 4.200.10
INDEX
6.200.20 (.165.004) (.244.008) Details of "A" part 1.25 -0.10 .049 -.004
+0.20 +.008
(Mounting height)
0.25(.010) "A"
1
4
0~8
0.80(.031)
0.370.08 (.015.003)
0.10(.004)
M
0.500.20 (.020.008) 0.600.15 (.024.006)
0.100.10 (.004.004) (Stand off)
0.10(.004)
C
2002 FUJITSU LIMITED F08005S-c-3-5
Dimensions in mm (inches) . Note : The values in parentheses are reference values.
16
MB3800
FUJITSU LIMITED
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, such as descriptions of function and application circuit examples, in this document are presented solely for the purpose of reference to show examples of operations and uses of Fujitsu semiconductor device; Fujitsu does not warrant proper operation of the device with respect to use based on such information. When you develop equipment incorporating the device based on such information, you must assume any responsibility arising out of such use of the information. Fujitsu assumes no liability for any damages whatsoever arising out of the use of the information. Any information in this document, including descriptions of function and schematic diagrams, shall not be construed as license of the use or exercise of any intellectual property right, such as patent right or copyright, or any other right of Fujitsu or any third party or does Fujitsu warrant non-infringement of any third-party's intellectual property right or other right by using such information. Fujitsu assumes no liability for any infringement of the intellectual property rights or other rights of third parties which would result from the use of information contained herein. The products described in this document are designed, developed and manufactured as contemplated for general use, including without limitation, ordinary industrial use, general office use, personal use, and household use, but are not designed, developed and manufactured as contemplated (1) for use accompanying fatal risks or dangers that, unless extremely high safety is secured, could have a serious effect to the public, and could lead directly to death, personal injury, severe physical damage or other loss (i.e., nuclear reaction control in nuclear facility, aircraft flight control, air traffic control, mass transport control, medical life support system, missile launch control in weapon system), or (2) for use requiring extremely high reliability (i.e., submersible repeater and artificial satellite). Please note that Fujitsu will not be liable against you and/or any third party for any claims or damages arising in connection with above-mentioned uses of the products. Any semiconductor devices have an inherent chance 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 Law of Japan, the prior authorization by Japanese government will be required for export of those products from Japan.
F0309 (c) FUJITSU LIMITED Printed in Japan

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