IR3638
High Frequency Synchronous
Step Down PWM Controller
for Tracking Applications
The IR3638 controller IC is designed to provide a simple
synchronous Buck regulator for on−board DC to DC applications in a
14−pin SOIC. The IR3638 is designed specifically for tracking
applications by providing the track input.
The IR3638 operates at a fixed internal 400 kHz switching
frequency allowing the use of small external components. The device
features a programmable soft start set by an external capacitor,
under−voltage lockout and output under−voltage detection that latches
off the device when an output short is detected.
Features
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MARKING
DIAGRAM
IR3638G
AWLYWW
1
14
1
A
WL
Y
WW
G
SOIC−14
D SUFFIX
CASE 751A
= Assembly Location
= Wafer Lot
= Year
= Work Week
= Pb−Free Package
•
•
•
•
•
•
•
•
•
•
Power up Sequencing / Tracking
Enable Input
Internal 400 kHz Oscillator
Programmable Soft−Start
Fixed Frequency Voltage Mode
PIN CONNECTIONS
FB
VP
NC
VCC
NC
LDRV
GND
(Top View)
1
NC
SS
COMP
NC
VC
HDRV
PGND
Applications
Tracking Applications
Game Consoles
Computing Peripheral Voltage Regulators
Graphics Cards
General DC to DC Converters
ORDERING INFORMATION
See detailed ordering and shipping information in the package
dimensions section on page 12 of this data sheet.
Figure 1. Typical Application Circuit
©
Semiconductor Components Industries, LLC, 2009
June, 2009
−
Rev. 0
1
Publication Order Number:
IR3638/D
IR3638
Table 1. PIN FUNCTION DESCRIPTION
Pin
1
2
3
4
5
6
7
8
9
Name
FB
VP/EN
NC
VCC
NC
LDRV
GND
PGND
HDRV
Description
Inverting input to the error amplifier. This pin is connected to the output of the regulator via resistor divider
to set the output voltage and provide feedback to the error amplifier.
Dual function pin. Non inverting input to the error amplifier. Enable input.
No Connect
This pin provides power for the internal blocks of the IC as well as powers the low side driver. A minimum
of 0.1
mF,
high frequency capacitor must be connected from this pin to power ground.
No Connect
Output driver for low side MOSFET.
IC ground for internal control circuitry.
Power Ground. This pin serves as a separate ground for the MOSFET drivers and should be connected to
the system’s power ground plane.
Output driver for high side MOSFET. The negative voltage at this pin may cause instability for the gate
drive circuit. To prevent this, a low forward voltage drop diode (e.g. BAT54 or 1N4148) is required
between this pin and Power Ground.
This pin powers the high side driver.
No Connect
Output of error amplifier. An external resistor and capacitor network is typically connected from this pin to
ground to provide loop compensation.
Soft start. This pin provides user programmable soft−start function. Connect an external capacitor from
this pin to ground to set the start up time of the output voltage.
No Connect
10
11
12
13
14
VC
NC
COMP
SS
NC
Table 2. ABSOLUTE MAXIMUM RATINGS
Rating
Main Supply Voltage Input
Main Supply Voltage Input
Supply Voltage for the High side driver
Supply Voltage for the High side driver 200 ns wide spikes, 400 kHz
VP/EN pin Voltage
FB pin Voltage
Rating
Thermal Resistance, Junction−to−Ambient (Note 2)
Storage Temperature Range
Junction Operating Temperature
ESD Withstand Voltage (Note 3)
Human Body Model
Machine Model
Moisture Sensitivity Level
200 ns wide spikes, 400 kHz
Symbol
V
CC
V
CC_SPK
V
C
V
C_SPK
V
P/EN
V
FB
Symbol
R
thja
T
stg
T
J
V
ESD
2.0
200
MSL
JEDEC Level 1 @ 260°C
kV
V
min
−0.3
−0.3
−0.3
−0.3
−0.3
−0.3
max
20
22
20
22
10 or V
CC
(Note 1)
10 or V
CC
(Note 1)
Value
90
−65
to 150
0 to 150
Unit
V
V
V
V
V
V
Unit
K/W
°C
°C
Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the
Recommended Operating Conditions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may affect
device reliability.
NOTE: All voltages are referenced to GND pin unless otherwise stated.
1. Maximum = 10 V or V
CC
, whichever is lower.
2. JEDEC High−K model
3. This device series contains ESD protection and exceeds the following tests:
Human Body Model (HBM)
±2.0
kV per JEDEC standard: JESD22−A114
Machine Model (MM)
±200
V per JEDEC standard: JESD22−A115
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IR3638
Table 3. RECOMMENDED OPERATING CONDITIONS
Symbol
V
CC
V
C
T
J
Definition
Supply Voltage
Supply Voltage
Junction Temperature
Min
7
Converter Voltage + 5 V, (Note 4)
0
Max
20
20
125
Units
V
V
°C
NOTE: All voltages are referenced to GND pin.
4. Depend on high side MOSFET V
GS
Table 4. ELECTRICAL SPECIFICATIONS
Unless otherwise specified, V
CC
= V
C
= 12 V, 0°C < T
J
< 125°C
Parameter
SUPPLY CURRENT
V
CC
Supply Current (Static)
V
CC
Supply Current (Dynamic)
V
C
Supply Current (Static)
V
C
Supply Current (Dynamic)
UNDER VOLTAGE LOCKOUT
V
CC
−Start−Threshold
V
CC
−Stop−Threshold
V
CC
−Hysteresis
Enable−Start−Threshold
Enable−Stop−Threshold
Enable−Hysteresis
FB UVLO
OSCILLATOR
Frequency
Ramp Amplitude
Min Duty Cycle
Max Duty Cycle
ERROR AMPLIFIER
FB Input Bias Current
FB Input Bias current
VP/EN Input Bias Current
Transconductance
Input Offset Voltage
VP/EN Common Mode Range
I
FB1
I
FB2
I
VP/EN
gm
V
OS
V
COMN
I
OTA (SINK)
I
OTA (SOURCE)
V
P/EN
= 0.8 V, V
COMP
= 2.0 V
(Note 5)
V
SS
= 3 V
V
SS
= 0 V
V
SS
= 3 V
440
−6
0.6
0
−0.1
64
−0.1
−0.5
1300
+6
1.5
−0.5
mA
mA
mA
mmho
mV
V
f
SW
V
RAMP
D
MIN
D
MAX
(Note 5)
V
FB
=1V, V
P/EN
= 0.8 V
f
SW
= 400 kHz, V
FB
= 0.6 V, V
P/EN
= 0.8 V
81
85
360
400
1.25
0
95
440
kHz
V
%
%
V
CC
UVLO (R)
V
CC
UVLO (F)
V
CC
(Hyst)
V
P/EN
UVLO (R)
V
P/EN
UVLO (F)
V
P/EN
(Hyst)
V
FB
UVLO
Supply voltage Rising
Supply voltage Falling
Supply ramping up and down
Supply voltage Rising
Supply voltage Falling
Supply ramping up and down
FB ramping down
6.3
6.0
0.2
0.6
0.56
25
0.3
6.6
6.3
0.3
0.65
0.6
42.5
0.4
7.0
6.6
0.4
0.7
0.66
60
0.5
V
V
V
V
V
mV
V
I
CC(Static)
I
CC(Dynamic)
I
C(Static)
I
C(Dynamic)
V
P/EN
= 0 V, No Switching
f
SW
= 400 kHz, C
L
= 1.5 nF
V
P/EN
= 0 V, No Switching
f
SW
= 400 kHz, C
L
= 1.5 nF
1.5
10
0.1
9
5
15
1
15
mA
mA
mA
mA
Symbol
Test Condition
Min
Typ
Max
Units
ERROR AMPLIFIER DESIGN SPECIFICATIONS
OTA output current
OTA output current
V
FB
= 1.2 V, V
P/EN
= 1.0 V,
V
COMP
= 2.0 V, (Note 5)
V
FB
= 0.8 V, V
P/EN
= 1.0 V,
V
COMP
= 2.0 V, (Note 5)
100
100
mA
mA
5. Guaranteed by Design but not tested in production.
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