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S-8533A25AFT-TB-G

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24P25-P27P28-P30P31-P33
STEP-DOWN, SYNCHRONOUS PWM CONTROL SWITCHING REGULATOR CONTROLLER
Rev.3.0_00
S-8533 Series
Seiko Instruments Inc.
7
Electrical Characteristics
Table 3
V
IN
= V
OUT
× 1.5 V, I
OUT
= V
OUT
/50 A (In case V
OUT
≤ 1.8 V, V
IN
= 2.7 V) (Ta = 25°C unless otherwise specified)
Parameter Symbol Conditions Min. Typ. Max. Unit
Measurement
Circuit
Output voltage
*1
V
OUT(E)
−
V
OUT(S)
× 0.98
V
OUT(S)
V
OUT(S)
× 1.02
V 2
Input voltage V
IN
−
2.7
−
16.0 V 1
Current consumption 1 I
SS1
No external parts, V
OUT
= V
OUT(S)
× 0.95
(Duty ratio 100%)
−
30 70 μA 1
Current consumption
during power-off
I
SSS
V
ON/OFF
= 0 V
− −
1.0 μA 1
I
PDRVH
No external parts, V
OUT
= V
OUT(S)
× 1.5,
V
IN
= 9.0 V, V
PDRV
= V
IN
− 0.2 V
−12 −18
−
mA 1
PDRV pin output current
I
PDRVL
No external parts, V
OUT
= V
OUT(S)
× 0.95,
V
IN
= 9.0 V, V
PDRV
= 0.2 V
19 27
−
mA 1
I
NDRVH
No external parts, V
OUT
= V
OUT(S)
× 1.5,
V
IN
= 9.0 V, V
NDRV
= V
IN
− 0.2 V
−10 −14
−
mA 1
NDRV pin output current
I
NDRVL
No external parts, V
OUT
= V
OUT(S)
× 0.95,
V
IN
= 9.0 V, V
NDRV
= 0.2 V
35 50
−
mA 1
S-8533A125,
S-8533A13A to 29A
−
V
OUT(E)
× 1.0%
V
OUT(E)
× 2.5%
V 2
Line regulation ΔV
OUT1
V
IN
= V
OUT(S)
× 1.2 to 16 V
*2
S-8533A30A to 60A
−
V
OUT(E)
× 1.0%
V
OUT(E)
× 2.0%
V 2
Load regulation ΔV
OUT2
I
OUT
= 10 μA to I
OUT
(see above) × 1.25
−
V
OUT(E)
× 0.5%
V
OUT(E)
× 1.0%
V 2
Output voltage
temperature coefficient
Δ
Δ
V
Ta V
OUT
OUT
•
Ta = −40 to +85°C
−
±100
−
ppm/°C
−
Oscillation frequency f
OSC
Measure waveform at the PDRV pin. 255 300 345 kHz 2
Maximum duty ratio MaxDuty
The same condition as l
SS1
. Measure waveform at
the PDRV pin.
100
− −
% 1
VOUT pin input current I
VOUT
V
OUT
= 5.0 V 0.01 0.1 4.0 μA 1
V
SH
The same condition as I
SS1
.
V
IN
= 2.7 V and check that PDRV pin = "L".
1.8
− −
V 1
ON/
OFF
pin input
voltage
V
SL
The same condition as I
SS1
.
V
IN
= 16.0 V and check that PDRV pin = "H".
− −
0.3 V 1
I
SH
The same condition as I
SS1
. V
ON/OFF
= V
IN
−0.1
−
0.1 μA 1
ON/
OFF
pin input
leakage current
I
SL
The same condition as I
SS1
. V
ON/OFF
= 0 V −0.1
−
0.1 μA 1
Soft-start time t
SS
The same condition as I
SS1
. Measure time until
PDRV pin oscillates.
5.0 8.0 16.0 ms 1
Efficiency EFFI *3, I
OUT
= 200 to 400 mA, S-8533A33A
−
94
−
% 3
External parts : Coil : Sumida Corporation CD105 (22 μH)
Diode : Matsushita Electric Industrial Co., Ltd. MA737 (Schottky diode)
Capacitor : Nichicon Corporation F93 (16 V, 47 μF, tantalum) × 2
Transistor : Toshiba Corporation 2SA1213
Base resistance : 1 kΩ
Base capacitor : 2200 pF
C
SS
: 4700 pF
C
NDRV
: 1000 pF
*1. V
OUT(S)
: Nominal output voltage value
V
OUT(E)
: Actual output voltage value : V
IN
= V
OUT
× 1.5 V, I
OUT
= V
OUT
/50 A (If V
OUT
≤ 1.8 V, V
IN
= 2.7 V.)
*2. In case V
OUT(S)
≤ 2.2 V, V
IN
= 2.7 to 16 V
*3. External parts Coil : Sumida Corporation CDRH104R (22 μH)
Capacitor : Nichicon Corporation F93 (16 V, 47 μF, tantalum) × 2
P-channel power MOS FET : Sanyo Electric Co., Ltd. CPH6303 (V
GS
= 10 V max.)
N-channel power MOS FET : Sanyo Electric Co., Ltd. CPH6403 (V
GS
= 10 V max.)
C
SS
: 4700 pF
STEP-DOWN, SYNCHRONOUS PWM CONTROL SWITCHING REGULATOR CONTROLLER
S-8533 Series
Rev.3.0_00
Seiko Instruments Inc.
8
Measurement Circuits
1.
VSS
0.1 μF
4700 pF
ON/OFF
CSS
PDRV
VOUT
NDRV
VIN
A
A
A
A A
Figure 4
2.
VSS
0.1 μF
C
NDRV
1000 pF
CD105
22 μH
MA737
2SA1213
2200 pF
1 k
Ω
F93
47 μF
F93
47 μF
F93
22 μF × 3
F93
22
μ
F
×
3
+
+
+
+
4700 pF
ON/OFF
CSS
PDRV
VOUT
NDRV
VIN
A
Figure 5
3.
VSS
0.1 μF
CDRH104R
22 μH
I
OUT
CPH6403
CPH6303
F93
47 μF
F93
47 μF
F93
22 μF
+ +
+
4700 pF
ON/OFF
CSS
PDRV
VOUT
NDRV
VIN
A
Figure 6
STEP-DOWN, SYNCHRONOUS PWM CONTROL SWITCHING REGULATOR CONTROLLER
Rev.3.0_00
S-8533 Series
Seiko Instruments Inc.
9
Operation
1. Synchronous PWM Control Step-down DC-DC Converter
1. 1 Synchronous Rectification
A synchronous rectifying DC-DC converter enables a greater reduction in the power consumption of the external
rectifying element compared with a conventional DC-DC converter. In addition, incorporating a P and N feed-
through prevention circuit reduces the feed-through current during operation of external transistors (P-channel and
N-channel), making the operating power consumption extremely low.
1. 2 PWM Control
The S-8533 Series is a DC-DC converter that uses pulse width modulation (PWM) and is characterized by its low
current consumption.
In conventional modulation PFM system DC-DC converters, pulses are skipped when they are operated with a low
output load current, causing variations in the ripple frequency of the output voltage and an increase in the ripple
voltage. Both of these effects constitute inherent drawbacks to those converters.
In the S-8533 Series, the pulse width varies in the range from 0 to 100% according to the load current, yet the ripple
voltage produced by the switching can easily be eliminated by a filter since the switching frequency is always
constant. When the pulse width is 0% (when there is no load or the input voltage is high), current consumption is
low since pulses are skipped.
2. Soft-Start Function
The S-8533 Series has a built-in soft-start circuit.
This circuit enables the output voltage (V
OUT
) to rise gradually over the specified soft-start time (t
SS
) to suppress the
overshooting of the output voltage, when the power is switched on or the ON/OFF pin is set “H”.
The soft-start time can be set with an external capacitance (C
SS
).
The time needed for the output voltage to reach 95% of the set output voltage value is calculated by the following
formula.
t
SS
[ms] = 0.002 × C
SS
[pF]
0
10
20
30
40
50
60
0 5000 10000 15000 20000
External capacitance (C
SS
) [pF]
Soft-start time (t
SS
) [ms]
Figure 7 Soft-Start Time
The value for C
SS
should be selected to give enough margin to the soft-start time against the power supply rise
time. If the soft-start time is short, possibility for output voltage overshoot, input current rush, and malfunction of the
IC increases.
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24P25-P27P28-P30P31-P33

S-8533A25AFT-TB-G

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Switching Controllers SYNC PWM CTRL STPDWN CTRLLR
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