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For assistance or to order, call (800) 531-5782
78ST212 Series
12V 2 AMP POSITIVE STEP-DOWN
INTEGRATED SWITCHING REGULATOR
Revised 6/30/98
Standard Application
Vin
C1
1
78ST212
• High Efficiency > 87%
• Wide Input Range
• Aluminum Heatsink for
Applications with Airflow
• Self-Contained Inductor
• Short Circuit Protection
• Over-Temperature Protection
Pin-Out Information
Pin Function
V
1
in
2 GND
V
3
out
C2
Vout
+
GNDGND
3
2
The 78ST212 is a series of wide
input voltage, 3-terminal Integrated
Switching Regulators (ISRs). With a
surge capability of 3A and an output
voltage that is laser trimmed, it is ideal
for inductive load applications such as
disk drive motors.
Ordering Information
78ST2 C
Output Voltage
12 = 12.0 Volts
(For dimensions and PC board
XX Y
Package Suffix
V = Vertical Mount
H = Horizontal Mount
layout see Package Style 600.)
C1 = Optional 1µF ceramic
C2 = Required 100µF electrolytic
Specifications
Characteristics
(Ta = 25°C unless noted) Symbols Conditions Min Typ Max Units
Output Current I
Input Voltage Range V
Output Voltage Tolerance ∆V
Line Regulation Reg
Load Regulation Regload 0.1 ≤ Io ≤ 2.0A — ±0.2 ±0.4 %V
V
Ripple/Noise V
o
Transient Response t
(with 100µF output cap) Vo over/undershoot — 3.0 — %V
Efficiency η Vin=17V, Io=2.0A — 87 — %
Switching Frequency ƒ
Absolute Maximum T
Operating Temperature Range
Recommended Operating T
Temperature Range at Vin= 24V, Io=2A
Thermal Resistance θja Free Air Convection, (40-60LFM) — 35 — °C/W
Storage Temperature T
Mechanical Shock — Per Mil-STD-883D, Method 2002.3 — 500 — G’s
Mechanical Vibration — Per Mil-STD-883D, Method 2007.2,
Weight — — — 11 — Grams
*ISR will operate down to no load with reduced specifications. **See Thermal Derating chart.
Note:
The 78ST212 Series requires a 100µF electrolytic or tantalum output capacitor for proper operation in all applications.
o
in
o
line
n
tr
o
a
a
s
Over Vin range
With forced air cooling
0.1 ≤ Io ≤ 2.0A 14.5 — 28 V
Over Vin range, Io= 2.0A
Ta= 0°C to +55°C
Over Vin range — ±0.4 ±0.8 %V
Vin=17V, Io=2.0A, Vo=12V — 1.0 — %V
50% load change — 100 — µSec
Over Vin and Io ranges 0.95 1.0 1.05 MHz
— -40 — +65 °C
Free Air Convection, (40-60LFM)
— -40 — +125 °C
20-2000 Hz, Soldered in a PC board
78ST212 SERIES
0.1* — 2.0 A
— ±1.0 ±2.0 %Vo
-40 — +55** °C
—10
—
o
o
o
o
G’s
Power Trends, Inc. 27715 Diehl Road, Warrenville, IL 60555 (800) 531-5782 Fax: (630) 393-6902 http://www.powertrends.com
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CHARACTERISTIC DATA
For assistance or to order, call (800) 531-5782
78ST212 Series
78ST212_ 12.0 VDC (See Note 1)
Efficiency vs Output Current
100
90
80
70
60
Efficiency (%)Ripple (mV)Iout (A)PD (Watts)
50
40
0.0 0.5 1.0 1.5 2.0
Iout (A)
Ripple vs Output Current
60
50
40
30
20
10
0
0.0 0.5 1.0 1.5 2.0
Iout (A)
DATA SHEETS
Vin
15V
18V
21V
24V
28V
Vin
15V
18V
21V
24V
28V
Thermal Derating (Ta) (See Note 2)
2.0
1.5
1.0
0.5
0.0
14 16 18 20 22 24 26 28
Vin (Volts)
60°C
70°C
85°C
Power Dissipation vs Output Current
3.0
2.5
2.0
1.5
1.0
0.5
0.0
0.0 0.5 1.0 1.5 2.0
Iout (A)
Note 1: All data listed in the above graphs, except for derating data, has been developed from actual products tested at 25°C. This data is considered typical data for the ISR.
Note 2: Thermal derating graphs are developed in free air convection cooling of 40-60 LFM. (See Thermal Application Notes.)
Vin
15V
18V
21V
24V
28V
Power Trends, Inc. 27715 Diehl Road, Warrenville, IL 60555 (800) 531-5782 Fax: (630) 393-6902 http://www.powertrends.com
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