Preliminary
RT9224C
DS9224C-01 May 2001
www.richtek.com
1
VRM 9.0 Synchronous PWM Buck Converter
Controller and Output Voltage Monitor
General Description
The RT9224C is a high speed switching controller
designed for use in Synchronous DC/DC buck
converter for modern CPUs. The regulated output
voltage is digitally programmable from 1.075V to
1.85V by a 5-bit DAC which provides initial accuracy
of 1%. The RT9224C drives two external N-channel
MOSFETs, providing high efficiency and eliminating
the need for high cost P-channel devices. It senses
the output current across the on-resistance of the N-
channel MOSFET and provides an adjustable
current limit without external sense resistor.
The RT9224C monitors the output voltage and
provides the output signal for power-good and over-
voltage protections. The switching frequency is
200kHz. The high switching frequency cooperating
with a high speed error amplifier maintains a fast
response to the dynamic load of modern CPUs.
Ordering Information
RT9224C
Features
Simple Voltage-mode PWM Control with Buck
Rectification
1% DAC Output Voltage Accuracy
5-Bit Digital-to-Analog Output Voltage Range
from 1.075V to 1.85V
Fast Transient Response and Excellent Output
Voltage Regulation
Fault Protection for Over-voltage and Over-
current
Power-good Output Voltage Monitor
Applications
Power Supply for VRM 9.0 Microprocessors
Low-voltage Distributed Power Supplies
High Power 5V to 1.075V~1.85V Switching
Regulator
Pin Configurations
Part Number
Pin Configurations
RT9224CCS
(Plastic SOP-20)
TOP VIEW
Operating temperature range
C: Commercial standard
Package type
S : SOP-20
1
2
3
4
5
6
7
8
9
10
VSEN
OCSET
SS
VID0
VID1
VID2
VID3
VID4
NC
FB
NC
OVP
VCC
LGATE
PGND
BOOT
UGATE
PHASE
PGOOD
GND
20
19
18
17
16
15
14
13
12
11
RT9224C
Preliminary
www.richtek.com
DS9224C-01 May 2001
2
Absolute Maximum Ratings
Supply Voltage
+15V
Boot Voltage
+15V
Input, Output or I/O Voltage
GND 0.3V to V
CC
+ 0.3V
Storage Temperature Range
65
C ~150
C
Package Thermal Resistance
SOP-20,
JA
87
C/W
Recommended Operating Conditions
Supply Voltage
+12V
10%
Ambient Temperature Range
0
C to 70
C
Junction Temperature Range
0
C
to 125
C
Electrical Characteristics
(T
A
= 25
C, recommended operating conditions, unless otherwise specified)
Parameter
Symbol
Test Conditions
Min
Typ
Max
Units
VCC Supply Current
Nominal Supply
I
CC
UGATE and LGATE Open
--
3
--
mA
Power-On Reset
VCC Rising Threshold
V
OCSET
= 4.5V
--
9.5
--
V
VCC Falling Threshold
V
OCSET
= 4.5V
--
7.5
--
V
Rising V
OCSET
Threshold
--
1.6
--
V
Oscillator
Free Running Frequency
170
200
230
KHz
Ramp Amplitude
V
OSC
--
1.9
--
V
P-P
Reference and DAC
DAC (VID0 VID4) Input Low Voltage
--
--
0.8
V
DAC (VID0 VID4) Input High Voltage
2.0
--
--
V
DACOUT Voltage Accuracy
-1.0
--
+1.0
%
Error Amplifier
DC Gain
--
65
--
dB
Gate Drivers
UGATE Source
R
UGATE
V
BOOT
- V
PHASE
= 12V
--
8
--
UGATE Sink
R
UGATE
V
UGATE
- V
PHASE
= 1V
--
5
--
LGATE Source
I
LGATE
VCC = 12V, V
LGATE
= 6V
--
500
--
mA
LGATE Sink
R
LGATE
V
LGATE
= 1V
--
5
--
To be continued
Preliminary
RT9224C
DS9224C-01 May 2001
www.richtek.com
3
Parameter
Symbol
Test Conditions
Min
Typ
Max
Units
Protection
Over-voltage Trip (VSEN/DACOUT)
--
115
120
%
OCSET Current Source
I
OCSET
V
OCSET
= 4.5V
167
200
233
A
OVP Sourcing Current
I
OVP
V
SEN
= 5.5V, V
OVP
= 0V
60
--
--
mA
Soft-Start Current
I
SS
V
SS
= 1.5V
--
10
--
A
Power Good
Upper Threshold (VSEN/DACOUT)
VSEN Rising
106
--
114
%
Lower Threshold (VSEN/DACOUT)
VSEN Falling
89
--
96
%
Hysteresis (VSEN/DACOUT)
Upper and Lower Threshold
--
2
--
%
PGOOD Voltage Low
V
PGOOD
I
PGOOD
= -5mA
--
0.5
--
V
Function Block Diagram
110%
90%
115%
POWER-ON
RESET (POR)
SOFT-
START
REFERENCE
TTL D/A
CONVERTER
(DAC)
OSCILLATOR
GATE
CONTROL
LOGIC
OVER-
VOLTAGE
OVER-
CURRENT
PGOOD
OVP
SS
BOOT
UGATE
PHASE
LGATE
PGND
GND
VCC
VSEN
OCSET
VID0
VID1
VID2
VID3
VID4
FB
DACOUT
ERROR
AMP
PWM
PWM
COMPARATOR
10
A
200
A
4.5V
INHIBIT
+
_
+
_
+
_
+
_
+
_
+
_
RT9224C
Preliminary
www.richtek.com
DS9224C-01 May 2001
4
Pin Description
Pin No. Pin Name
Pin Function
1
VSEN
Output voltage monitoring input for OVP & PGOOD
2
OCSET
Over current set pin, sinks 200A through a resistor (R
OCS
) from this pin to upper N-
MOSFET to set the trip point:
An over-current trip cycles the soft-start function
3
SS
Soft start speed is set by internal 10A current source and capacitor from this pin to GND
4
VID0
Switching regulator output voltage setting
5
VID1
Switching regulator output voltage setting
6
VID2
Switching regulator output voltage setting
7
VID3
Switching regulator output voltage setting
8
VID4
Switching regulator output voltage setting
9
NC
No connection
10
FB
Feedback input pin
11
GND
IC signal ground
12
PGOOD
Open drain logic output
This pin is pulled low when the converter output is not within 10% of the DACOUT
reference voltage
13
PHASE
Current limit sense input
14
UGATE
High side driver output
15
BOOT
Driver power
16
PGND
Low side driver GND
17
LGATE
Low side driver output
18
VCC
Power supply input
19
OVP
Over voltage protection
This pin is pulled high when the VSEN voltage is over 15% of the DACOUT reference
voltage
20
NC
No connection
I
PEAK
=
200A R
OCS
MOSFET-on resistance
Preliminary
RT9224C
DS9224C-01 May 2001
www.richtek.com
5
Table 1 Output Voltage Program
Pin Name
VID4
VID3
VID2
VID1
VID0
Nominal Output Voltage DACOUT
1
1
1
1
1
1.075V
1
1
1
1
0
1.100V
1
1
1
0
1
1.125V
1
1
1
0
0
1.150V
1
1
0
1
1
1.175V
1
1
0
1
0
1.200V
1
1
0
0
1
1.225V
1
1
0
0
0
1.250V
1
0
1
1
1
1.275V
1
0
1
1
0
1.300V
1
0
1
0
1
1.325V
1
0
1
0
0
1.350V
1
0
0
1
1
1.375V
1
0
0
1
0
1.400V
1
0
0
0
1
1.425V
1
0
0
0
0
1.450V
0
1
1
1
1
1.475V
0
1
1
1
0
1.500V
0
1
1
0
1
1.525V
0
1
1
0
0
1.550V
0
1
0
1
1
1.575V
0
1
0
1
0
1.600V
0
1
0
0
1
1.625V
0
1
0
0
0
1.650V
0
0
1
1
1
1.675V
0
0
1
1
0
1.700V
0
0
1
0
1
1.725V
0
0
1
0
0
1.750V
0
0
0
1
1
1.775V
0
0
0
1
0
1.800V
0
0
0
0
1
1.825V
0
0
0
0
0
1.850V
Note: (1) 0:Connected to GND (2) 1:Open
RT9224C
Preliminary
www.richtek.com
DS9224C-01 May 2001
6
Typical Application Circuit
Component Selection Notes:
C
OUT
, C
IN
Each 1000
F 6.3WV DC, Sanyo MV-GX or Equivalent.
L2 Core: Micrometals T50-52B; Winding: 10 Turns of 16AWG.
L1 Core: Micrometals T50-52; Winding: 5 Turns of 18AWG.
D2 3A, 40V Schottky, Motorola MBR340 or Equivalent.
Q1, Q2 PHB83N03LT; PHB95N03LT
+
+
MONITOR AND
PROTECTION
OSC
D/A
V
IN
= 5V
+12V
F1
L1
1
H
C
IN
5
1000
F
2K
2N6394
2
1
F
15V
0.1
F
10
0.1
F
1000pF
1K
Q1
L2 - 3
H
+V
O
C
OUT
9
1000
F
4.99K
0.68
F
750K
Q2
D2
GND
FB
1
19
2
3
4
5
6
7
8
10
11
12
13
14
15
16
17
18
VSEN
SS
VID0
VID2
VID3
VID4
PGND
LGATE
PHASE
VID1
BOOT
OCSET
UGATE
PGOOD
OVP
VCC
+
_
+
_
Preliminary
RT9224C
DS9224C-01 May 2001
www.richtek.com
7
Package Information
Dimensions In Millimeters
Dimensions In Inches
Symbol
Min
Max
Min
Max
A
12.598
13.005
0.496
0.512
B
7.391
7.595
0.291
0.299
C
2.362
2.642
0.093
0.104
D
0.330
0.508
0.013
0.020
F
1.194
1.346
0.047
0.053
H
0.229
0.330
0.009
0.013
I
0.102
0.305
0.004
0.012
J
10.008
10.643
0.394
0.419
M
0.381
1.270
0.015
0.050
M
H
B
J
B
A
C
I
F
D
RT9224C
Preliminary
www.richtek.com
DS9224C-01 May 2001
8
RICHTEK TECHNOLOGY CORP.
Headquarter
5F, No. 20, Taiyuen Street, Chupei City
Hsinchu, Taiwan, R.O.C.
Tel: (8863)5526789 Fax: (8863)5526611
RICHTEK TECHNOLOGY CORP.
Taipei Office (Marketing)
8F-1, No. 137, Lane 235, Paochiao Road, Hsintien City
Taipei County, Taiwan, R.O.C.
Tel: (8862)89191466 Fax: (8862)89191465
Email: marketing@richtek.com
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