MB3789APFV-XXXE1 [CYPRESS]
Switching Regulator;
| 型号： | MB3789APFV-XXXE1 |
| 厂家： | 
CYPRESS |
| 描述： | Switching Regulator 开关 |
| 文件： | 总33页 (文件大小：1149K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
The following document contains information on Cypress products.
FUJITSU MICROELECTRONICS
DATA SHEET
DS04-27268-1E
ASSP for Power Management Applications
BIPOLAR
Switching Regulator Controller
(Supporting External Synchronization)
MB3789A
■ DESCRIPTION
The MB3789A is a PWM (pulse width modulation) switching regulator controller supporting an external sync
signal. This IC incorporates two error amplifiers which can be used respectively for voltage control and current
control, allowing the IC to serve as a DC/DC converter with current regulating functions.
This is the ideal IC for supplying power to the back-lighting fluorescent tube for a liquid crystal display (LCD)
device such as a camera-integrated VTR.
■ FEATURES
• Wide range of operating power supply voltages: 3 V to 18 V
• Low current consumption: 1.5 mA (Typ)
• Wide input voltage range of error amplifier: –0.2 V to VCC – 1.8 V
• Built-in two error amplifier
• Oscillator capable of operating with an external sync signal
• Built-in timer latch short protection circuit
• Variable dead time provides control over total operating range
• Output supporting a power MOSFET
• 16-pin SSOP package mountable at high density
■ APPLICATIONS
• LCD back light
etc.
Copyright©2008 FUJITSU MICROELECTRONICS LIMITED All rights reserved
2008.9
MB3789A
■ PIN ASSIGNMENT
(TOP VIEW)
VCC1
VREF
C T
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
GND
OUT
VCC2
CB
SYNC
SCP
DTC
FB1*1
FB2 *2
−IN2*2
+IN2*2
−IN1*1
+IN1*1
(FPT-16P-M05)
*1: Pins on error amplifier 1
*2: Pins on error amplifier 2
2
DS04-27268-1E
MB3789A
■ PIN DESCRIPTION
Pin no.
Pin symbol
I/O
Function
Error amplifier 1 inverting input pin
7
8
–IN1
+IN1
FB1
I
I
Error amplifier 1 noninverting input pin
Error amplifier 1 output pin
6
O
I
10
9
–IN2
+IN2
FB2
Error amplifier 2 inverting input pin
Error amplifier 2 noninverting input pin
Error amplifier 2 output pin
I
I/O
11
O
control
unit
Output bootstrap pin.
13
CB
—
Connect a capacitor between the CB and OUT pins to bootstrap the
output transistor.
5
SCP
DTC
OUT
—
I
Capacitor connection pin for short-circuit protection circuit
Dead time control pin
12
15
O
Totem-pole output pin
Sawtooth waveform frequency setting capacitor/resistor connection
pin
3
4
CT
—
I
Sawtooth
waveform
oscillator
SYNC
External sync signal input pin
1
14
2
VCC1
VCC2
VREF
—
—
O
Reference power supply, control circuit power-supply pin
Output circuit power-supply pin
Reference voltage output pin
Power-
supply
circuit
16
GND
—
Ground pin
DS04-27268-1E
3
MB3789A
■ BLOCK DIAGRAM
CB
13
14
Error amp. 1
PWM comparator
+IN1
−IN1
FB1
8
7
6
VCC2
OUT
15
Error amp. 2
10 kΩ
+IN2
−IN2
9
10
FB2 11
12
DTC
−0.9 V
−0.3 V
8 µA
4 µA
SCP comparator 1
1.25 V
SCP comparator 3
1.25 V
2 µA
VREF
SCP comparator 2
1
2
V 1
CC
1.1 V
1.8 V
Under voltage
Reference Power
Sawtooth
wave
oscillator
Lock-out
protection
circuit
SR latch
voltage
supply
ON/OFF
circuit
V
REF
16
5
4
3
GND
SCP
SYNC
C
T
External sync signal
4
DS04-27268-1E
MB3789A
■ FUNCTIONAL DESCRIPTION
1. Switching Regulator Functions
(1) Reference voltage generator
The reference voltage generator uses the voltage supplied from the power supply pin (pin 1) to generate a
temperature-compensated, referencevoltage(about2.50V)asthereferencesupplyvoltagefortheIC’sinternal
circuitry.
The reference voltage can be output, up to 50 µA, to an external device through the VREF pin (pin 2).
This regulated reference voltage can be used as the reference voltage for the switching regulator and also
used for setting the dead time.
(2) Sawtooth waveform oscillator
With a timing capacitor and a timing resistor connected to the CT pin (pin 3), the sawtooth waveform oscillator
generates a sawtooth wave which remains stable even with supply voltage variations or temperature changes.
The sawtooth wave is input to the PWM comparator. The amplitude of oscillating waveform is 0.3 V to 0.9 V.
In addition, the oscillator can be used for external synchronization, where it generates a sawtooth waveform
synchronous to the input signal from the SYNC pin (pin 4).
(3) Error amplifiers
The error amplifiers detect the output voltage from the switching regulator and outputs the PWM control signal.
Since they support a wide range of in-phase input voltages from –0.2 V to “VCC – 1.8 V”, they can be set easily
from an external power supply.
An arbitrary loop gain can be set by connecting a feedback resistor and capacitor from the error amplifier output
pin to the inverting input pin, enabling stable phase compensation to the system.
This IC can make a current-regulated DC/DC converter using the two internal error amplifiers respectively for
voltage control and current control.
(4) PWM comparator
The PWM comparator is a voltage comparator with one inverting input and three noninverting inputs, serving
as a voltage-pulse width converter for controlling the output duty depending on the input voltage.
The PWM comparator turns on the output transistor during the interval in which the sawtooth wave voltage
level is lower than the voltage levels at all of the error amplifier output pins, the SCP pin (pin 5), and at the
DTC pin (pin 12).
(5) Output circuit
The output circuit is a power MOSFET driven, output circuit in a totem-pole configuration. It can drive the gate
voltage up to near the supply voltage with a bootstrap capacitor connected between the OUT pin (pin 15) and
CB pin (pin 13). (See “■ SETTING THE BOOTSTRAP CAPACITOR (CBS).”)
DS04-27268-1E
5
MB3789A
2. Protection Functions
(1) Timer-latch short-circuit protection circuit
SCP comparator 1 detects the output voltage levels of error amplifiers 1 and 2. When the output voltage level
of both of the two error amplifiers reaches 1.25 V, the timer circuit is actuated to start charging the external
protection-enable capacitor connected to the SCP pin (pin 5).
If the error amplifier output is not restored to the normal voltage level before the capacitor voltage reaches
1.8 V, the latch circuit is actuated to turn off the output transistor while making the dead time 100%.
To reset the actuated protection circuit, turn the power supply on back. (See “■ SETTING THE SOFT START/
SHORT-CIRCUIT DETECTION TIME.”)
(2) Low input voltage malfunction preventive circuit
The transient state or a momentary decrease in supply voltage, which occurs when the power supply is turned
on, may cause errors in the control IC, resulting in breakdown or degradation of the system. The low input
voltagemalfunctionpreventivecircuitdetectstheinternalreferencevoltagelevelaccordingtothesupplyvoltage
level and, if the input voltage is low, turn off the output transistor and maintains the SCP pin (pin 5) at 0 V while
making the dead time 100%.
The circuit restores voltage supply when the supply voltage reaches its threshold voltage.
6
DS04-27268-1E
MB3789A
■ ABSOLUTE MAXIMUM RATINGS
(Ta = +25°C)
Rating
Parameter
Symbol
Condition
Unit
Min
—
Max
20
Power supply voltage
Power dissipation
VCC
PD
—
V
mW
°C
—
440*
+85
+125
Ta +25°C
Operating temperature
Storage temperature
Top
Tstg
—
—
–30
–55
°C
*: When mounted on a 10 cm-square double-side 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.
■ RECOMMENDED OPERATING CONDITIONS
(Ta = +25°C)
Value
Typ
5.0
Parameter
Symbol
Condition
Unit
Min
3.0
—
Max
18
VCC1
VCC2
—
V
V
Power supply voltage
6.0
18
Reference voltage output
current
IOR
—
–50
–30
—
µA
Error amp. input voltage
VI
—
–0.2
–70
—
VCC – 1.8
—
V
IO+
–40
mA
CB = 4700 pF, t 2 µs
Output current
IO–
RT
—
10
40
39
70
200
6800
200
+85
mA
kΩ
pF
CB = 4700 pF, t 2 µs
Timing resistance
—
—
—
—
Timing capacitance
Oscillation frequency
Operating temperature
CT
470
1
1000
20
fOSC
TOP
kHz
°C
–30
+25
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 representatives beforehand.
DS04-27268-1E
7
MB3789A
■ ELECTRICAL CHARACTERISTICS
(VCC1 = 5 V, VCC2 = 6 V, Ta = +25°C)
Value
Unit
Parameter
Symbol
Condition
Min
Typ
Max
Output voltage
VREF
IOR = 0 µA
2.400
2.500
2.600
V
Output voltage
temperature
variation
∆VREF/VREF Ta = –30°C to +85°C*
—
0.2
2
%
Reference
voltage block
Input stability
Line
Load
IOS
VCC = 3.0 V to 18 V
—
—
1
10
10
mV
mV
µA
V
Load stability
IOR = 0 µA to –50 µA
VREF = 0 V
2
Short output current
–700
—
–450
1.76
1.56
200
1.4
–300
2.30
—
VTH
VTL
—
Under
Threshold voltage
voltage
lockout
protection
circuit
—
1.30
60
V
Hysteresis width
Reset voltage (VCC)
Charge current
VHYS
VR
—
—
—
mV
V
1.0
—
ICHG
VT0
VSCP 0.9 V
Duty cycle = 0%
Duty cycle = 100%
—
–2.8
0.2
–2.0
0.3
–1.2
0.4
1.0
1.90
µA
V
Soft start
block
Threshold voltage
Threshold voltage
VT100
VTH
0.8
0.9
V
1.70
1.80
V
Input standby
voltage
Short circuit
detection
block
VSTB
—
1.15
1.25
1.35
mV
Input latch voltage
Input source current
VI
II
—
—
50
100
mV
VSCP = 1.5 V
–8.4
–6.0
–3.6
µA
CT = 1000 pF,
RT = 39 kΩ
Oscillator frequency
fOSC
17
—
20
1
23
10
kHz
%
Frequency voltage
variation
∆f/fdv
VCC = 3 V to 18 V
Triangular
waveform
oscillator
block
Frequency
temperature
variation
∆f/fdT
Ta = –30°C to +85°C*
—
3
—
%
Synchronous pin
input current
ISYNC
VTHSY = 5 V
0.9
1.3
2.2
mA
V
Synchronous pin
threshold voltage
VTHSY
—
0.65
0.75
0.85
*: Standard design value
(Continued)
8
DS04-27268-1E
MB3789A
(Continued)
(VCC1 = 5 V, VCC2 = 6 V, Ta = +25°C)
Value
Unit
Parameter
Symbol
Condition
VFB = 0.6 V
Min
—
Typ
—
Max
10
Input offset voltage
Input offset current
Input bias current
VIO
IIO
IB
mV
nA
nA
VFB = 0.6 V
VFB = 0.6 V
—
—
100
—
–200
–30
Common mode
input voltage range
VCM
—
–0.2
—
VCC – 1.8
V
Common mode
rejection ratio
CMRR
AV
—
—
60
60
—
100
100
800
—
—
—
dB
dB
Error
amplifier
Voltage gain
Frequency
bandwidth
BW
AV = 0 dB*
kHz
VOM+
VOM–
IOM+
—
—
VREF – 0.3
2.4
0.05
60
—
0.3
—
V
V
Maximum output
voltage range
—
Output sink current
VFB = 0.6 V
30
µA
Output source
current
IOM–
VFB = 0.6 V
—
–2
–0.6
mA
VT0
VT100
Dtr
Duty cycle = 0%
Duty cycle = 100%
Vdt = VREF/4.2
—
0.2
0.8
45
0.3
0.9
55
0.4
1.0
65
V
V
Threshold voltage
Dead time
control block
ON duty cycle
%
Input bias current
IIbdt
–500
0.2
0.8
30
–100
0.3
0.9
60
—
nA
V
VT0
Duty cycle = 0%
Duty cycle = 100%
—
0.4
1.0
—
Threshold voltage
PWM
comparator
block
VT100
IIN+
V
Input sink current
µA
mA
Input source current
IIN–
—
—
–2
–0.6
CL = 2000 pF,
CB = 4700 pF
VOH
VOL
5.5
—
6.0
1.1
—
V
V
Output block Output voltage
Power supply
CL = 2000 pF,
CB = 4700 pF
1.4
ICC1
ICC2
—
—
—
1.15
350
1.65
500
mA
General
current when output
off
—
µA
*: Standard design value
DS04-27268-1E
9
MB3789A
■ TYPICAL CHARACTERISTICS
Power supply current vs.
power supply voltage characteristics
2.4
Output power supply current vs.
power supply voltage characteristics
500
400
300
200
100
0
VCC1 = 5 V
Ta = +25°C
VCC2 = 6 V
Ta = +25°C
2.0
1.6
1.2
0.8
0.4
0
0
4
8
12
16
20
0
4
8
12
16
20
Power supply voltage VCC1 (V)
Power supply voltage VCC2 (V)
Reference voltage vs.
power supply voltage characteristics
Reference voltage vs.
ambient temperature characteristics
2.56
2.54
2.52
2.50
2.48
2.46
2.44
5.0
4.0
3.0
2.0
1.0
0
VCC1 = 5 V
VCC2 = 6 V
IOR = 0 µA
VCC2 = 6 V
IOR = 0 µA
Ta = +25°C
0
4
8
12
16
20
−40 −20
0
+20 +40 +60 +80 +100
Power supply voltage VCC1 (V)
Ambient temperature Ta (°C)
Sawtooth waveform maximum amplitude voltage vs.
timing capacitance characteristics
Sawtooth wave frequency vs.
timing resistance characteristics
(With C
T
/R
T
oscillation)
(With C
T
/R
T
oscillation)
500 k
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
VCC1 = 5 V
VCC1 = 5 V
VCC2 = 6 V
SYNC = GND
Ta = +25°C
VCC2 = 6 V
RT = 39 kΩ
SYNC = GND
Ta = +25°C
100 k
50 k
10 k
5 k
CT = 470 pF
1 k
CT = 1500 pF
CT = 4700 pF
500
CT = 6800 pF
100
2 k
102
5 × 102 103 5 × 103 104
5 × 104
5 k 10 k
50 k 100 k
500 k 1 M
Timing capacitance CT (pF)
Timing resistance RT (Ω)
(Continued)
10
DS04-27268-1E
MB3789A
Sawtooth waveform period vs.
timing capacitance characteristics
Duty vs. sawtooth wave
frequency characteristics
(With C /R oscillation)
(With C
T
/RT
oscillation)
T
T
100
500
VCC1 = 5 V
VCC2 = 6 V
VDT = 0.6 V
CT = Variable
RT = 39 kΩ
SYNC = GND
Ta = −25°C
80
60
40
20
VCC1 = 5 V
100
50
VCC2 = 6 V
RT = 39 kΩ
SYNC = GND
Ta = +25°C
10
5
2
0
2 × 10 5 × 10 102 5 × 102 103
5 × 103 104
5 × 104
200 500 1 k
5 k 10 k
50 k 100 k
500 k
Timing capacitance CT (pF)
Sawtooth wave frequency f (Hz)
Sawtooth wave frequency vs.
ambient temperature characteristics
Sawtooth wave frequency vs.
ambient temperature characteristics
(In external synchronization)
(With C
T
/RT oscillation)
VCC1 = 5 V
VCC1 = 5 V
VCC2 = 6 V
CT = 1500pF
RT = 43 kΩ
VCC2 = 6 V
CT = 1500pF
RT = 39 kΩ
+10
+5
0
+10
+5
0
SYNC = GND
fSYNC = 15.0 kHz
−5
10
−5
−10
−40
−20
0
+20 +40 +60 +80 +100
−40 −20
0
+20 +40 +60 +80 +100
Ambient temperature Ta (°C)
Ambient temperature Ta (°C)
Gain vs. frequency and phase vs.
frequency characteristics
Measurement circuit for gain-frequency
characteristics and phase-frequency characteristics
2.5 V 2.5 V
VCC1 = 5 V
VCC2 = 6 V
Ta = +25°C
40
20
180
90
4.7 kΩ 240 kΩ
4.7 kΩ
Av
0
0
OUT
10 µF
φ
Error amp.
IN
−20
−40
−90
−180
4.7 kΩ
4.7 kΩ
1 k
10 k
100 k
1 M
10 M
Frequency f (Hz)
(Continued)
DS04-27268-1E
11
MB3789A
(Continued)
Duty vs. DTC pin voltage characteristics
Output pin (OUT) voltage and current waveforms
VCC1 = 5 V,
VCC2 = 6 V
100
80
60
40
20
0
VCC1 = 5 V
6
VCC2 = 6 V
CT = 1500 pF
RT = 39 kΩ
SYNC = GND
4
2
0
100
50
0
−50
−100
0
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1
DTC pin voltage Vdt (V)
0
4
8
12
16
20
Time t (µs)
Power comsumption vs.
ambient temperature characteristics
500
440
400
300
200
100
0
−30 −20
0
+20
+40
+60
+80
+100
Ambient temperature Ta (°C)
12
DS04-27268-1E
MB3789A
■ APPLICATION NOTE
• Setting the Output Voltage
Set the output voltage by connecting the input pins (+IN, –IN) and output pin (FB) of error amplifiers 1 and 2 as
shown in Figures 1 and 2.
VREF
+
VOUT
VREF
+
VOUT
=
(R1 + R2)
R
R
R1
R2
2 × R2
RNF
Figure 1 Setting the output voltage (positive output voltage (VOUT))
VREF
VREF
R1
R2
R
R
−
VOUT = −
(R1 + R2) + VREF
2 × R1
RNF
−
VOUT
Figure 2 Setting the output voltage (negative output voltage (VOUT))
• Setting the Oscillation Frequency
The oscillation frequency can be set by connecting the timing resistor (RT) and the timing capacitor to the CT
terminal (pin 3) .
Oscillation frequency : fOSC
780000
fOSC (kHZ) =:
CT(pF) × RT(kΩ)
DS04-27268-1E
13
MB3789A
• Connection for Output Control with One Error Amplifier
This IC can make up a system using only one of the two error amplifiers. In this case, connect the +IN and –IN
pins of the unused error amplifier to the VREF and GND pins, respectively, and leave the FB pin open.
When VCC – 1.8 V < VREF, divide the VREF voltage using a resistor and apply the voltage to the +IN pin.
VREF
2
+IN1
8
−IN1
7
FB1
6
“Open”
Figure 1 Connection without using error amplifier 1
VREF
2
+IN2
9
−IN2
10
FB2
11
“Open”
Figure 2 Connection without using error amplifier 2
14
DS04-27268-1E
MB3789A
•
• Connecting the Sawtooth Waveform Oscillator
1. Connection for internal oscillation
For internal oscillation, connect the frequency setting capacitor (CT) and resistor (RT) to the CT pin (pin 3) and
leave the SYNC pin (pin 4) open or connect it to GND.
The oscillation frequency can be set with the CT and RT constants.
CT
SYNC
4
3
CT
RT
Leave “open” or connect to GND
Figure 5 Connection for internal oscillation
2. Connection for external synchronous oscillation
For external synchronous oscillation, connect the frequency setting capacitor (CT) and resistor (RT) to the CT pin
(pin 3) and connect the external sync signal to the SYNC pin (pin 4).
In this case, select the CT and RT conditions so that the oscillation frequency is 5% to 10% lower than the
frequency of the external sync signal excluding the setting error of the oscillation frequency.
CT
SYNC
4
3
External sync signal
CT
RT
Figure 6 Connection for external synchronous oscillation
DS04-27268-1E
15
MB3789A
• Setting the Dead Time
When the device is set for step-up inverting output based on the flyback method, the output transistor is fixed
to a full-ON state (ON duty = 100%) when the power supply is turned on. To prevent this problem, you may
determine the voltage at the DTC pin (pin 12) from the VREF voltage so you can set the output transistor’s dead
time (maximum ON-duty period) as shown in Figure 7 below.
1. Setting the Dead Time
When setting the dead time, use resistors as shown in Figure 7 to connect the VREF and DTC pins to GND. When
the voltage at the DTC pin (pin 12) is lower than the sawtooth wave output voltage from the oscillator, the output
transistor is turned off.
To set the dead time, see “Duty vs. DTC pin voltage” (in “■ STANDARD CHARACTERISTIC CURVES”).
R2
R1 + R2
Vdt =
× VREF
2. Connection without setting the dead time
If you do not set the dead time, connect the VREF and DTC pins as shown in Figure 8.
VREF
DTC
2
R1
R2
12
Vdt
Figure 7 Connection for setting the dead time
VREF
DTC
2
12
Figure 8 Connection without setting the dead time
16
DS04-27268-1E
MB3789A
• Setting the Soft Start / Short-circuit Detection Time
Connecting capacitor CPE to the SCP pin (pin 5) as shown in Figure 9 enables a soft start and short-circuit
protection.
8 µA
4 µA
SCP comparator 1
1.25 V
Output OFF
SCP comparator 3
1.25 V
SCP comparator 2
2 µA
VREF
1.1 V
1.8 V
Low input
voltage
protection
circuit
SR latch
5
SCP
CPE
Figure 9 Soft start/short-circuit detection circuit
2
1
0
1.8 V
1.25 V
0.9 V
Output short-circuit
tPE
100%
Output short-circuit
50%
ts
0%
0.3 V
Soft start
Time t (s)
Figure 10 SCP pin operating waveform
DS04-27268-1E
17
MB3789A
1. Soft start
To prevent surge currents when the IC is turned on, you can set a soft start by connecting capacitor CPE to the
SCP pin (pin 5).
~
•Softstart time(ts): Time required up to duty cycle 50% with output on
~
tS (s) 0.15 × CPE (µF)
2. Protection from short circuit
SCP comparator 1 always compares the output voltage levels at error amplifiers 1 and 2 with the 1.25 V
reference voltage.
When the load conditions for the switching regulator are stable, the outputs from error amplifiers 1 and 2 do
not vary and thus short-circuit protection control remains balanced. In this case, the SCP pin (pin 5) is held at
the soft start end voltage (about 1.25 V).
If the load conditions change rapidly and the output voltage level of both of the two error amplifiers reaches
1.25 V, for example, because of a short-circuit of a load, capacitor CPE is charged further. When capacitor CPE
is charged up to about 1.8 V, the SR latch is set and the output drive transistor is turned off. At this time, the
~
dead time is set to 100%, capacitor CPE is discharged, and the SCP pin becomes 50 mV.
• Short-circuit detection time (tPE)
~
tPE (s) 0.09 × CPE (µF)
3. Connection without using short-circuit protection
Add a clamp circuit as shown in Figure 11 so that the clamp voltage (VCRP) falls within the following range when
a short-circuit is detected: 1.0 V < VCRP < 1.7 V
Clamp circuit
5
SCP
VCRP
CPE
Figure 11 Connection without using short-circuit protection
18
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MB3789A
• Setting the Bootstrap Capacitor (CBS)
When a bootstrap capacitor is connected, it raises the output-ON voltage (at the OUT pin (pin 15) when the
~
external MOS FET is turned “ON”) to the VCC2 level. It can therefore drive the MOS FET at a higher threshold
voltage (Vth).
1. Connecting the bootstrap capacitor
Connect the bootstrap capacitor between the CB pin (pin 13) and OUT pin (pin 15).
VCC2
VCBS
id
CB
13
14
VCC2
VCC1
CBS
iC
External
MOS FET
I
15
OUT
10 kΩ
VOUT
: Charge current ic
: Discharge current id
Figure 12 Circuit with a bootstrap capacitor connected and current flow
• Calculation of bootstrap capacitance
500 × 106
VCC2 – 2.6
CBS
× tON (Max) [pF]
tON (Max): Maximum ON duty time
DS04-27268-1E
19
MB3789A
2. Operation of the bootstrap capacitor
When voltage VOUT at the OUT pin (pin 15) is “L” level, the voltages (VC1) at both ends of the bootstrap capacitor
CBS is charged up to the VCC2 voltage level by charge current (iC).
~
When VOUT changes from “L” level to “H” level, the CB pin (pin 13) voltage VCBS rises to 2 × VCC2 and VOUT
reaches almost the VCC2 level.
The charge accumulated at CBS at this time is released by discharge current id (output unit supply current).
See Figure 12 for circuit operation.
(VCC1 = 5 V, VCC2 = 6 V, CBS = 4700 pF)
2 V
12
*2
10
8
*1
V
CBS
6
4
2
0
6
4
2
0
V
OUT
2 V
10 µs
0
20
40
60
80
100
t
ON
t
OFF
Time t (µs)
*1: Use the device with a setting of VCBS 18 V.
*2: The slant of VCBS is determined by the value of discharge current i
d
(output unit supply current).
Figure 13 Bootstrap operating waveform
20
DS04-27268-1E
MB3789A
3. Connection with no bootstrap capacitor
Connect the CB pin (pin 13) and VCC2 pin (pin 14) as shown in Figure 14.
VCC2
CB
13
14
15
VCC2
External
MOS FET
OUT
Note: Under a condition of “VCC2 − Vth < 1.1 V”, bootstrap capacitor CBS should be connected because
the external MOS FET cannot be driven sufficiently.
Vth: External MOS FET threshold voltage
Figure 14 Connection with no bootstrap capacitor connected
DS04-27268-1E
21
MB3789A
• Equivalent Series Resistance of Smoothing Capacitor and System Stability
The equivalent series resistance (ESR) value of a smoothing capacitor for the DC/DC converter largely affects
the loop phase characteristic.
Depending on the ESR value, the phase characteristic causes the ideal capacitor in a high-frequency domain
advance the loop phase (as shown in Figures 16 and 17) and thus the system is improved in stability. In contrast,
using a smoothing capacitor with low ESR lowers system stability. Use meticulous care when a semiconductor
electrolytic capacitor with low ESR (such as an OS capacitor) or a tantalum capacitor is used. (The next page
gives an example of reduction in phase margin when an OS capacitor is used.)
L
Tr
RC
VIN
D
RL
C
Figure 15 Basic circuit of step-down DC/DC converter
20
0
0
(2)
−90
−20
−40
−60
(2)
(1) : RC = 0 Ω
(2) : RC = 31 mΩ
(1)
(1) : RC = 0 Ω
(2) : RC = 31 mΩ
(1)
−180
10
100
1 k
Frequency f (Hz)
10 k
100 k
10
100
1 k
Frequency f (Hz)
10 k
100 k
Figure 16 Gain vs. frequency
Figure 17 Phase vs. frequency
22
DS04-27268-1E
MB3789A
(Reference data)
~
Changing the smoothing capacitor from an aluminum electrolytic capacitor (RC 1.0 Ω) to a low-ESR semicon-
~
ductor electrolytic capacitor (OS capacitor: RC 0.2 Ω) halves the phase margin. (See Figures 19 and 20.)
VOUT
+
VO
CNF
AV-phase characteristic
in this range
−IN
VIN
FB
+IN
R2
R1
VREF/2
Error amplifier
Figure 18 DC/DC converter Av vs. phase measurement diagram
AI electrolytic capacitor gain vs. frequency, phase vs. Frequency (DC/DC converter +5 V output)
60
VCC = 10 V
RL = 25 Ω
40
20
180
90
CP = 0.1 µF
AV
+
VO
φ⇒
AI electrolytic capacit
220 µF (16 V)
RC 1.0 Ω: fOSC = 1 kHz
62°
0
0
−90
−180
−20
−40
GND
10
100
1 k
Frequency f (Hz)
10 k
100 k
Figure 19 Gain vs. frequency
DS04-27268-1E
23
MB3789A
OS capacitor gain vs. frequency, phase vs. frequency (DC/DC converter +5 V output)
60
VCC = 10 V
RL = 25 Ω
CP = 0.1 µF
AV
40
20
180
90
+
VO
OS capacitor
22 µF (16 V)
φ⇒
0
0
RC 0.2 Ω: fOSC = 1 kHz
27°
−90
−180
−20
−40
GND
10
100
1 k
10 k
100 k
Frequency f (Hz)
Figure 20 Phase vs. frequency characteristic curves
24
DS04-27268-1E
MB3789A
■ APPLICATION EXAMPLE
10 µH
10 µF
VCC
(5 V)
2
V
REF
1
2
100 kΩ
100 kΩ
14
13
8
+IN1
18 kΩ
CB
7
6
−IN1
2.7 kΩ
100 kΩ
FB1
4700 pF
150 kΩ
100 kΩ
+IN2
9
MB3789A
Back
light
15
OUT
10
11
12
−IN2
10 kΩ
100 kΩ
FB2
150 kΩ
100 kΩ
10 µF
GND 16
DTC
SYNC
4
C
T
SCP
5
3
1 µF
39 Ω
22 kΩ
33 pF
4.7 kΩ
1500 pF
4.7 µF
33 kΩ
Synchronous signal
DS04-27268-1E
25
MB3789A
■ USAGE PRECAUTION
1. Do not configure the IC over the maximum ratings
lf the lC is used over the maximum ratings, the LSl may be permanently damaged.
It is preferable for the device to normally operate within the recommended usage conditions. Usage outside of
these conditions can have a bad effect on the reliability of the LSI.
2. Use the devices within recommended operating conditions
The recommended operating conditions are under which the LSl is guaranteed to operate.
The electrical ratings are guaranteed when the device is used within the recommended operating conditions
and under the conditions stated for each item.
3. Printed circuit board ground lines should be set up with consideration for common
impedance
4. Take appropriate measures against static electricity
• Containers for semiconductor materials should have anti-static protection or be made of conductive material.
• After mounting, printed circuit boards should be stored and shipped in conductive bags or containers.
• Work platforms, tools, and instruments should be properly grounded.
• Working personnel should be grounded with resistance of 250 kΩ to 1 MΩ between body and ground.
5. Do not apply negative voltages
The use of negative voltages below –0.3 V may create parasitic transistors on LSI lines, which can cause
malfunctions.
■ ORDERING INFORMATION
Part number
Package
Remarks
16-pin Plastic SSOP
(FPT-16P-M05)
MB3789APFV-❏❏❏E1
Lead-free version
■ RoHS COMPLIANCE INFORMATION OF LEAD (Pb) FREE VERSION
The LSI products of Fujitsu Microelectronics with “E1” are compliant with RoHS Directive , and has observed
the standard of lead, cadmium, mercury, hexavalent chromium, polybrominated biphenyls (PBB) , and polybro-
minated diphenyl ethers (PBDE) .
A product whose part number has trailing characters “E1” is RoHS compliant.
26
DS04-27268-1E
MB3789A
■ MARKING FORMAT (LEAD FREE VERSION)
3789A
E1
INDEX
Lead-free version
DS04-27268-1E
27
MB3789A
■ LABELING SAMPLE (LEAD FREE VERSION)
Lead-free mark
JEITA logo
JEDEC logo
MB123456P - 789 - GE1
(3N) 1MB123456P-789-GE1 1000
G
Pb
(3N)2 1561190005 107210
QC PASS
PCS
1,000
MB123456P - 789 - GE1
ASSEMBLED IN JAPAN
2006/03/01
MB123456P - 789 - GE1
1/1
1561190005
0605 - Z01A 1000
The part number of a lead-free product has the trailing
characters “E1”.
28
DS04-27268-1E
MB3789A
■ PACKAGE DIMENSION
16-pin plastic SSOP
Lead pitch
0.65 mm
4.40 × 5.00 mm
Gullwing
Package width
package length
×
Lead shape
Sealing method
Mounting height
Weight
Plastic mold
1.45mm MAX
0.07g
Code
(Reference)
(FPT-16P-M05)
P-SSOP16-4.4×5.0-0.65
16-pin plastic SSOP
Note 1) *1 : Resin protrusion. (Each side : +0.15 (.006) Max).
Note 2) *2 : These dimensions do not include resin protrusion.
Note 3) Pins width and pins thickness include plating thickness.
Note 4) Pins width do not include tie bar cutting remainder.
(FPT-16P-M05)
15.00 0.10(.197 .004)
*
0.17 0.03
(.007 .001)
16
9
2 4.40 0.10 6.40 0.20
*
(.173 .004) (.252 .008)
INDEX
Details of "A" part
1.25 –+00..1200
(Mounting height)
.049 +–..000048
1
8
LEAD No.
"A"
0.65(.026)
0.24 0.08
(.009 .003)
M
0.13(.005)
0~8
°
0.10 0.10
(.004 .004)
(Stand off)
0.50 0.20
(.020 .008)
0.25(.010)
0.60 0.15
(.024 .006)
0.10(.004)
Dimensions in mm (inches).
Note: The values in parentheses are reference values.
C
2003-2008 FUJITSU MICROELECTRONICS LIMITED F16013S-c-4-7
Please confirm the latest Package dimension by following URL.
http://edevice.fujitsu.com/package/en-search/
DS04-27268-1E
29
MB3789A
MEMO
30
DS04-27268-1E
MB3789A
MEMO
DS04-27268-1E
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MB3789A
FUJITSU MICROELECTRONICS LIMITED
Shinjuku Dai-Ichi Seimei Bldg., 7-1, Nishishinjuku 2-chome,
Shinjuku-ku, Tokyo 163-0722, Japan
Tel: +81-3-5322-3347 Fax: +81-3-5322-3387
http://jp.fujitsu.com/fml/en/
For further information please contact:
North and South America
Asia Pacific
FUJITSU MICROELECTRONICS AMERICA, INC.
1250 E. Arques Avenue, M/S 333
Sunnyvale, CA 94085-5401, U.S.A.
Tel: +1-408-737-5600 Fax: +1-408-737-5999
http://www.fma.fujitsu.com/
FUJITSU MICROELECTRONICS ASIA PTE. LTD.
151 Lorong Chuan,
#05-08 New Tech Park 556741 Singapore
Tel : +65-6281-0770 Fax : +65-6281-0220
http://www.fmal.fujitsu.com/
Europe
FUJITSU MICROELECTRONICS SHANGHAI CO., LTD.
Rm. 3102, Bund Center, No.222 Yan An Road (E),
Shanghai 200002, China
Tel : +86-21-6146-3688 Fax : +86-21-6335-1605
http://cn.fujitsu.com/fmc/
FUJITSU MICROELECTRONICS EUROPE GmbH
Pittlerstrasse 47, 63225 Langen, Germany
Tel: +49-6103-690-0 Fax: +49-6103-690-122
http://emea.fujitsu.com/microelectronics/
Korea
FUJITSU MICROELECTRONICS PACIFIC ASIA LTD.
10/F., World Commerce Centre, 11 Canton Road,
Tsimshatsui, Kowloon, Hong Kong
Tel : +852-2377-0226 Fax : +852-2376-3269
http://cn.fujitsu.com/fmc/en/
FUJITSU MICROELECTRONICS KOREA LTD.
206 Kosmo Tower Building, 1002 Daechi-Dong,
Gangnam-Gu, Seoul 135-280, Republic of Korea
Tel: +82-2-3484-7100 Fax: +82-2-3484-7111
http://kr.fujitsu.com/fmk/
Specifications are subject to change without notice. For further information please contact each office.
All Rights Reserved.
The contents of this document are subject to change without notice.
Customers are advised to consult with 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 MICROELECTRONICS device; FUJITSU MICROELECTRONICS
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 MICROELECTRONICS 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 MICROELECTRONICS
or any third party or does FUJITSU MICROELECTRONICS warrant non-infringement of any third-party's intellectual property right or
other right by using such information. FUJITSU MICROELECTRONICS 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 MICROELECTRONICS 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.
Exportation/release of any products described in this document may require necessary procedures in accordance with the regulations of
the Foreign Exchange and Foreign Trade Control Law of Japan and/or US export control laws.
The company names and brand names herein are the trademarks or registered trademarks of their respective owners.
Edited: Business & Media Promotion Dept.
相关型号：
MB3793-27APF-XXX
Power Supply Management Circuit, Fixed, 1 Channel, BIPolar, PDSO8, 5.30 X 6.35 MM, 2.25 MM HEIGHT, 1.27 MM PITCH, PLASTIC, SOP-8
FUJITSU
MB3793-27APF-XXXE1
Power Supply Management Circuit, Fixed, 1 Channel, BIPolar, PDSO8, 5.30 X 6.35 MM, 2.25 MM HEIGHT, 1.27 MM PITCH, ROHS COMPLIANT, PLASTIC, SOP-8
FUJITSU
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