DATA SHEET
SKY87250: 400 mA Low-Noise Step-Down Converter
in a Micro-Inductor Package
Applications
Bluetooth
®
headsets
Cellular phones
Digital cameras
Hard disk drives
PDAs and handheld computers
Portable media and MP3 players
USB devices
Description
The SKY87250
Switcher
TM
step-down converter delivers up to
400 mA to support an adjustable 0.6 V to V
IN
output from 2.7 V to
5.5 V input supply. Its low supply current, small size, and high
switching frequency make the SKY87250 the ideal choice for
portable applications.
The SKY87250 maintains a low 40
A
no-load quiescent current.
The 2.0 MHz switching frequency minimizes the output
capacitance requirement while keeping switching losses low. The
SKY87250 feedback and control delivers excellent load regulation
and transient response with a small output capacitor.
The SKY87250 maintains high efficiency throughout the load
range. The unique low-noise, light-load architecture produces
reduced ripple and spectral noise. Over-temperature and short-
circuit protection safeguards the SKY87250 and system
components from damage.
The ultra-small, 8-pin, 2.4 x 2.4 mm DLN package footprint,
integrated inductor, and minimal capacitance requirements, make
the SKY87250 ideal for compact designs.
Figure 1 shows the typical application circuit size comparison. A
typical application circuit is shown in Figure 2. The pin
configuration is shown in Figure 3. Signal pin assignments and
functional pin descriptions are provided in Table 1.
Features
V
IN
range: 2.5 V to 5.5 V
Adjustable output voltage: 0.6 V to V
IN
Output current: 400 mA
Up to 95% efficiency
Low-noise, light-load architecture
No load quiescent current: 40
A
Switching frequency: 2.0 MHz
Internal soft-start control
Over-temperature and current-limit protection
Shutdown current: <1
A
Small 4.7
F
output capacitor
Temperature range:
40 C
to +85
C
Compact integrated micro-inductor (inductor) DLN (8-pin,
2.4 × 2.4 mm) package (MSL1, 260 °C per JEDEC-J-STD-020)
Skyworks
Green™ products are compliant with
all applicable legislation and are halogen-free.
For additional information, refer to
Skyworks
Definition of Green™,
document number
SQ04-0074.
tc74
Figure 1. Typical Application Circuit Size Comparison
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
201922D • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice • January 21, 2014
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DATA SHEET • SKY87250 400 MA LOW-NOISE STEP-DOWN CONVERTER IN A MICRO-INDUCTOR PACKAGE
V
IN
2.7 V to 5.5 V
1
VP
U1
OUT
5
R1
adj
VIN
FB
4
R2
59 kΩ
V
OUT
2
C1
4.7
μF
6
ON/OFF
SKY87250
EN
GND
3
C2
4.7
μF
7
8
N/C
PGND
tc64
Figure 2. SKY87250 Typical Application Circuit
VP
VIN
GND
FB
1
2
3
4
8
7
6
5
N/C
PGND
EN
OUT
tc65
Figure 3. SKY87250 8-Pin DLN
(Top View)
Table 1. SKY87250 Signal Descriptions
Pin #
1
2
3
4
5
6
7
8
VP
VIN
GND
FB
OUT
EN
PGND
N/C
Name
Description
Input power pin; connect to the source of the P-channel MOSFET. Connect to the input capacitor.
Input bias voltage for the converter.
Non-power signal ground pin.
Feedback input pin. Connect this pin to an external resistive divider for adjustable output.
DC-DC converter output.
Enable pin. A logic high enables normal operation. A logic low shuts down the converter.
Power ground. Input power return pin; connect to the source of the N-channel MOSFET. Connect to the output and input capacitor return.
Not internally connected.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
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January 21, 2014 • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice • 201922D
DATA SHEET • SKY87250 400 MA LOW-NOISE STEP-DOWN CONVERTER IN A MICRO-INDUCTOR PACKAGE
Electrical and Mechanical Specifications
The absolute maximum ratings of the SKY87250 are provided in
Table 2. Recommended operating conditions are provided in
Table 3, and electrical specifications are provided in Table 4.
Table 2. SKY87250 Absolute Maximum Ratings (Note 1)
Parameter
Input voltage and bias power to PGND
FB to
GND
EN to
GND
AGND to PGND
OUT RMS current capability
Junction temperature range
Maximum soldering temperature (at leads, 10 seconds)
Maximum power dissipation (Note 2) (Note 3)
Maximum junction-to-ambient thermal resistance (Note 2)
Symbol
V
IN
, V
P
V
FB
V
EN
V
GND
I
OUT
T
J
T
LEAD
P
D
JA
Typical performance characteristics of the SKY87250 are
illustrated in Figures 4 through 33.
Minimum
0.3
0.3
0.3
0.3
Typical
Maximum
+6.0
V
IN
+ 0.3
V
IN
+ 0.3
+0.3
Units
V
V
V
V
A
1
40
300
150
158
+150
°C
°C
mW
°C/W
Note 1:
Exposure to maximum rating conditions for extended periods may reduce device reliability. There is no damage to device with only one parameter set at the limit and all other
parameters set at or below their nominal value. Exceeding any of the limits listed may result in permanent damage to the device.
Note 2:
Mounted on 1 inch
2
FR4 circuit board.
Note 3:
Derate 7.4 mW/C above 40
C
ambient temperature.
CAUTION:
Although this device is designed to be as robust as possible, Electrostatic Discharge (ESD) can damage this device. This
device must be protected at all times from ESD. Static charges may easily produce potentials of several kilovolts on the human
body or equipment, which can discharge without detection. Industry-standard ESD precautions should be used at all times.
Table 3. SKY87250 Recommended Operating Conditions
Parameter
Ambient temperature
Input voltage
Operating junction temperature
T
A
V
IN
T
J
Symbol
Minimum
40
2.7
40
Typical
Maximum
+85
5.5
+140
Units
°C
V
°C
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
201922D • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice • January 21, 2014
3
DATA SHEET • SKY87250 400 MA LOW-NOISE STEP-DOWN CONVERTER IN A MICRO-INDUCTOR PACKAGE
Table 4. SKY87250 Electrical Specifications (Note 1)
(C
IN
= 4.7
F,
C
OUT
= 4.7
F
, V
IN
= V
P
= 3.6 V, V
EN
= V
IN
, GND = PGND, T
A
= –40 °C to 85 °C [Typical Values are at T
A
= 25 °C], Unless
Otherwise Noted)
Parameter
Input voltage
Output voltage
Maximum continuous output current
capability
No load supply current
Shutdown current
Input under-voltage lockout
FB regulation threshold
FB leakage current
Line regulation
Load regulation
Oscillator frequency
On-time resistance
Off-time resistance
Soft-start period
Over-temperature shutdown
threshold
EN logic level high
EN logic level low
EN input current
V
IN
V
OUT
I
OUT
I
Q
I
SHDN
V
UVLO
V
FB
I
FB
∆V
OUT
/V
OUT
∆V
OUT
/V
OUT
f
OSC
R
TON
R
TOFF
t
SS
T
SHDN
V
IH
V
IL
I
EN
V
EN
= 0 V or V
IN
1.0
VP to OUT resistance (high-side MOSFET
on-resistance + DCR)
VP to PGND resistance (low-side MOSFET
on-resistance + DCR)
Enable rising edge to output regulation
Hysteresis = 15 °C
140
1.4
0.4
+1.0
°C
V
V
A
T
A
= 25 °C
No load current; not switching
EN =
GND
V
CC
rising
V
IN
= 2.7 V to 5.5 V, 10 mA load, T
A
= 25 °C
V
IN
= 2.7 V to 5.5 V, 10 mA load,
T
A
= –40 °C to 85 °C
V
FB
= 1 V
V
IN
= 2.7 V to 5.5 V
10 mA to 400 mA load
0.1
0.3
2.0
800
650
100
588
582
1.8
600
Symbol
V
P
, V
IN
Test Condition
Min
2.7
0.6
400
40
100
1.0
2.5
612
618
200
Typical
Max
5.5
V
IN
Units
V
V
mA
A
A
V
mV
mV
nA
%
%
MHz
m
m
s
Note 1:
Performance is guaranteed only under the conditions listed in this table.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
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January 21, 2014 • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice • 201922D
DATA SHEET • SKY87250 400 MA LOW-NOISE STEP-DOWN CONVERTER IN A MICRO-INDUCTOR PACKAGE
Typical Performance Characteristics
100
90
80
1.0
0.8
Output Voltage Error (%)
0.6
0.4
0.2
0.0
-0.2
-0.4
-0.6
-0.8
V
IN
= 3.6 V
V
IN
= 4.2 V
V
IN
= 5.0 V
V
IN
= 5.5 V
Efficiency (%)
70
60
50
40
30
0.1
1
10
100
V
IN
= 3.6 V
V
IN
= 4.2 V
V
IN
= 5.0 V
V
IN
= 5.5 V
1000
-1.0
0.1
1
10
100
1000
Output
Current
(mA)
Output
Current
(mA)
Figure 4. Efficiency vs Load
(V
OUT
= 3.3 V, R3 = 500
,
C3 = 100 pF)
Figure 5. Load Regulation
(V
OUT
= 3.3 V, R3 = 500
,
C3 = 100 pF)
100
90
80
1.0
0.8
Output Voltage Error (%)
0.6
0.4
0.2
0.0
-0.2
-0.4
-0.6
-0.8
V
IN
= 3.6 V
V
IN
= 4.2 V
V
IN
= 5.0 V
V
IN
= 5.5 V
1
10
100
1000
Efficiency (%)
70
60
50
40
30
0.1
V
IN
= 3.6 V
V
IN
= 4.2 V
V
IN
= 5.0 V
V
IN
= 5.5 V
1
10
100
1000
-1.0
0.1
Output
Current
(mA)
Output
Current
(mA)
Figure 6. Efficiency vs Load
(V
OUT
= 2.5 V, R3 = 500
,
C3 = 100 pF)
Figure 7. Load Regulation
(V
OUT
= 2.5 V, R3 = 500
,
C3 = 100 pF)
100
90
80
1.0
0.8
V
IN
= 2.7 V
V
IN
= 3.6 V
V
IN
= 4.2 V
V
IN
= 5.0 V
V
IN
= 5.5 V
Output Voltage Error (%)
1000
0.6
0.4
0.2
0.0
-0.2
-0.4
-0.6
-0.8
-1.0
0.1
1
10
100
Efficiency (%)
70
60
50
40
30
20
0.1
1
10
100
V
IN
= 2.7 V
V
IN
= 3.6 V
V
IN
= 4.2 V
V
IN
= 5.0 V
V
IN
= 5.5 V
1000
Output
Current
(mA)
Output
Current
(mA)
Figure 8. Efficiency vs Load
(V
OUT
= 1.8 V, R3 = 0
,
C3 = 0 pF)
Figure 9. Load Regulation
(V
OUT
= 1.8 V, R3 = 0
,
C3 = 0 pF)
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
201922D • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice • January 21, 2014
5
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