E fficien cy of the 1M H z 10 V -28 V to 5 V /3A S te p-D ow n C onve rte r (Fron t P ag
SC4525F
Pin Configuration
Ordering Information
Device
SC4525FSETRT
()(2)
SW
IN
RSET
GND
1
2
3
4
9
8
7
6
5
BST
FB
COMP
S S /E N
Package
SOIC-8 EDP
Evaluation Board
SC4525FEVB
Notes:
() Available in tape and reel only. A reel contains 2,500 devices.
(2) Available in lead-free package only. Device is fully WEEE and RoHS
compliant and halogen-free.
(8 - Pin SOIC - EDP)
Marking Information
yyww=Date code (Example: 0752)
xxxxx=Semtech Lot No. (Example: E900)
2
SC4525F
Absolute Maximum Ratings
V
IN
Supply Voltage ……………………………… -0.3 to 24V
BST Voltage ……………………………………………… 40V
BST Voltage above SW …………………………………… 24V
SS Voltage ……………………………………………-0.3 to 3V
FB Voltage ……………....…………………………… -0.3
to 7V
SW Voltage ………………………………………… -0.6 to V
IN
SW Transient Spikes (0ns Duration)……… -2.5V to V
IN
+.5V
Peak IR Reflow Temperature ………………………….
(2)
Thermal Information
Junction to Ambient
()
……………………………… 36°C/W
Junction to Case
()
…………………………………
5.5°C/W
Maximum Junction Temperature……………………… 50°C
Storage Temperature ………………………… -65 to +50°C
Lead Temperature (Soldering) 0 sec ………………… 300°C
Recommended Operating Conditions
Input Voltage Range ……………………………… 3V to 8V
Maximum Output Current ……………………………… 3A
Operating Ambient Temperature …………… -40 to +05°C
Operating Junction Temperature …………… -40 to +25°C
260°C
ESD Protection Level ………………………………… 2000V
Exceeding the above specifications may result in permanent damage to the device or device malfunction. Operation outside of the parameters specified in the
Electrical Characteristics section is not recommended.
NOTES-
() Calculated from package in still air, mounted to 3” x 4.5”, 4 layer FR4 PCB with thermal vias under the exposed pad per JESD5 standards.
(2) Tested according to JEDEC standard JESD22-A4-B.
Electrical Characteristics
Unless otherwise noted, V
IN
= 2V, V
BST
= 5V, V
SS
= 2.2V, -40°C < T
A
= T
J
< 25°C, R
SET
= 60.4kΩ.
Parameter
Input Supply
Input Voltage Range
V
IN
Start Voltage
V
IN
Start Hysteresis
V
IN
Quiescent Current
V
IN
Quiescent Current in Shutdown
Conditions
Min
3
Typ
Max
8
Units
V
V
mV
V
IN
Rising
2.70
2.82
225
2.95
V
COMP
= 0 (Not Switching)
V
SS/EN
= 0, V
IN
= 2V
2
40
2.6
52
mA
µA
Error Amplifier
Feedback Voltage
Feedback Voltage Line Regulation
FB Pin Input Bias Current
Error Amplifier Transconductance
Error Amplifier Open-loop Gain
COMP Pin to Switch Current Gain
COMP Maximum Voltage
COMP Source Current
COMP Sink Current
V
IN
= 3V to 8V
V
FB
= V, V
COMP
= 0.8V
0.980
.000
0.005
-70
300
60
5.2
-340
.020
V
%/V
nA
µ
Ω
-
dB
A/V
V
µA
V
FB
= 0.9V
V
FB
= 0.8V, V
COMP
= 0.8V
V
FB
= .2V, V
COMP
= 0.8V
(Note )
I
SW
= -3.9A
3.9
2.35
7
25
Internal Power Switch
Switch Current Limit
Switch Saturation Voltage
5.
380
6.6
600
A
mV
3
SC4525F
Electrical Characteristics (Cont.)
Unless otherwise noted, V
IN
= 2V, V
BST
= 5V, V
SS
= 2.2V, -40°C < T
A
= T
J
< 25°C, R
SET
= 60.4kΩ.
Parameter
Minimum Switch On-time
Minimum Switch Off-time
Switch Leakage Current
Minimum Bootstrap Voltage
BST Pin Current
Conditions
V
IN
= 0 V,
R
SW
= 0Ω
V
IN
= 6 V,
R
SW
= 6Ω
I
SW
= -3.9A
I
SW
= -3.9A
Min
70
30
Typ
20
75
Max
230
30
0
Units
ns
ns
µA
V
mA
.8
00
2.3
50
Oscillator
Switching Frequency
Foldback Frequency
R
SET
= 60.4kΩ
R
SET
= 60.4kΩ, V
FB
= 0
275
35
350
65
425
00
kHz
kHz
Soft Start and Overload Protection
SS/EN Shutdown Threshold
SS/EN Switching Threshold
Soft-start Charging Current
Soft-start Discharging Current
Hiccup Arming SS/EN Voltage
Hiccup SS/EN Overload Threshold
Hiccup Retry SS/EN Voltage
0.2
0.3
.2
.9
.6
2.4
.5
3.2
0.4
.4
V
V
µA
µA
V
V
.2
V
V
FB
= 0 V
V
SS/EN
= 0 V
V
SS/EN
= .5 V
V
SS/EN
Rising
V
SS/EN
Falling
V
SS/EN
Falling
0.95
2.5
.9
0.6
.0
Over Temperature Protection
Thermal Shutdown Temperature
Thermal Shutdown Hysteresis
Note : Switch current limit does not vary with duty cycle.
65
0
°C
°C
4
SC4525F
Pin Descriptions
SO-8
2
3
4
Pin Name
SW
IN
RSET
GND
Pin Function
Emitter of the internal NPN power transistor. Connect this pin to the inductor, the freewheeling diode and the
bootstrap capacitor.
Power supply to the regulator. It is also the collector of the internal NPN power transistor. It must be closely by-
passed to the ground plane with
a capacitor.
Connect a 60.4kW resistor from this pin to ground.
Ground pin
Soft-start and regulator enable pin. A capacitor from this pin to ground provides soft-start and overload hiccup
functions. Hiccup can be disabled by overcoming the internal soft-start discharging current with an external pull-
up resistor connected between the SS/EN and the IN pins. Pulling the SS/EN pin below 0.2V completely shuts off
the regulator to low current state.
The output of the internal error amplifier. The voltage at this pin controls the peak switch current. A RC compensa-
tion network at this pin stabilizes the regulator.
The inverting input of the error amplifier. If V
FB
falls below 0.8V, then the switching frequency will be reduced to
improve short-circuit robustness (see Applications Information for details).
Supply pin to the power transistor driver. Tie to an external diode-capacitor bootstrap circuit to generate drive
voltage higher than V
IN
in order to fully enhance the internal NPN power transistor.
The exposed pad serves as a thermal contact to the circuit board.
While the exposed pad is electrically isolated, it
is suggested to be soldered to the ground plane of the PC board.
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