Power Switching Regulators
TC33163
TC33163
Power Switching Regulators
FEATURES
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Output Switch Current in Excess of 3.0A
Operation from 2.5V to 40V Input
Low Standby Current
Precision 2% Reference
Controlled Duty Cycle Oscillator
Driver with Bootstrap Capability for
Increased Efficiency
Cycle-by-Cycle Current Limiting
Internal Thermal Shutdown Protection
Low Voltage Indicator Output for Direct
Microprocessor Interface
Heat Tab Power Package
GENERAL DESCRIPTION
The TC33163 series are monolithic power switching
regulators that contain the primary functions required for
DC-to-DC converters. This series is specifically designed
to be incorporated in step-up, step-down, and voltage-
inverting applications with a minimum number of external
components.
These devices consist of two high gain voltage feedback
comparators, temperature compensated reference, con-
trolled duty cycle oscillator, driver with bootstrap capability
for increased efficiency, and a high current output switch.
Protective features consist of cycle-by-cycle current limiting,
and internal thermal shutdown. Also included is a low
voltage indicator output designed to interface with micropro-
cessor based systems. These devices are contained in a
16-Pin dual-in-line heat tab plastic package for improved
thermal conduction.
TYPICAL APPLICATIONS
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Set-Top Boxes
Industrial Controllers
Network Boxes
Automotive
Computing
Consumer Electronics
ORDERING INFORMATION
Part
Number
TC33163EOE
TC33163EPE
Package
16-Pin SOIC (W)
16-Pin PDIP (N)
Temperature
Range
T
A
= - 40° to + 85°C
T
A
= - 40° to + 85°C
REPRESENTATIVE BLOCK DIAGRAM
PIN CONFIGURATIONS
I
PK
Sense 8
I
LIMIT
9
Driver
Collector
–
+
16-Pin SOIC/PDIP
LVI Output 1
Voltage
Feedback 2 2
Voltage
Feedback 1 3
4
GND
5
12
11
10
Switch
Collector
Timing
Capacitor
6
16 Bootstrap Input
15
14
13
GND
Switch
Emitter
V
CC
Timing
Capacitor
7
+
6
OSC
10
Switch
Collector
11
5
GND
4
Voltage
Feedback 1 3
Voltage
Feedback 2
LVI Output
2
LVI
+
+
–
Control Logic
and Thermal
Shutdown
12
GND
13
14
VFB
+
+
–
Switch
Emitter
15
Bootstrap
16
Input
+
V
CC
7
I
PK
Sense 8
9 Driver Collector
1
(Top View)
(Bottom View)
This device contains 114 active transistors.
TC33163-1 5/16/00
1
TelCom Semiconductor reserves the right to make changes in the circuitry and specifications of its devices.
Power Switching Regulators
TC33163
ABSOLUTE MAXIMUM RATINGS*
Power Supply Voltage ..................................... V
CC
= 40V
Switch Collector Voltage Range .... V
C (SWITCH)
= –1.0 to 40V
Switch Emitter Voltage Range V
E (SWITCH)
= –2.0 to V
C (SWITCH)
Switch Collector to Emitter Voltage ........ V
CE(SWITCH)
= 40V
Switch Current (Note 1) ..................................... I
SW
= 3.4A
Driver Collector Voltage .............. V
C(DRIVER)
= –1.0 to 40V
Driver Collector Current ....................... I
C (DRIVER)
= 150mA
Bootstrap Input Current Range (Note 1) ...... I
BS
= –100 to +100mA
Current Sense Input Voltage Range:
....................... V
LPK(SENSE)
= (V
CC
– 7.0) to (V
CC
+1.0) V
Feedback and Timing Capacitor Input Roltage Range:
......................................................... V
IN
= –1.0 to + 7.0V
Low Voltage Indicator Output Voltage Range: ..................
....................................................... V
C(LVI)
= –1.0 to +40V
Low Voltage Indicator Output Sink Current ....... I
C (LVI)
= 10mA
Thermal Characteristics:
16-Pin PDIP (N) Package
Thermal Resistance, Junction-to-Air ...... R
θJA
= 80°C/W
Thermal Resistance, Junction-to-Case ........... R
θJC
= 15°C/W
(Pins 4, 5 12, 13)
16-Pin SOIC (W) Package
Thermal Resistance, Junction-to-Air ...... R
θJA
= 94°C/W
Thermal Resistance, Junction-to-Case ........... R
θJC
= 18°C/W
(Pins 4, 5 12, 13)
Operating Junction Temperature .................. T
J
= +150°C
Operating Ambient Temperature (Note 3) ... T
A
= –40 to +85°C
Storage Temperature Range ......... T
STG
= –65 to +150°C
*This is a stress rating only, and functional operation of the device at these
or any other conditions beyond those indicated in the operation section of
the specifications is not implied. Exposure to absolute maximum ratings
conditions for extended periods of time may affect device reliability.
ELECTRICAL CHARACTERISTICS:
V
CC
= 15V, Pin 16 = V
CC,
C
T
= 620pF, for typical values T
A
= 25°C, for
min/max values T
A
is the operating temperature range that applies (Note 3), unless otherwise noted.
Symbol
Oscillator
f
OSC
Frequency
T
A
= 25°C
Total variation over V
CC
= 2.5V to 40V,
and Temperature
46
45
—
—
8.0
—
—
4.9
—
4.85
—
50
—
225
25
9.0
1.25
0.55
5.05
0.008
—
100
54
55
—
—
10
—
—
5.2
0.03
5.25
200
kHz
Parameter
Test Conditions
Min
Typ
Max
Units
I
CHG
I
DISCHG
I
CHG
/ I
DISCHG
V
OSC(P)
V
OSC(V)
V
TH(FB1)
Charge Current
Discharge Current
Charge to Discharge Current Ratio
Sawtooth Peak Voltage
Sawtooth Valley Voltage
Threshold Voltage
T
A
= 25°C
Line Regulation (V
CC
= 2.5V to 40V, T
A
= 25°C)
Total Variation Over Line, and Temperature
V
FB1
= 5.05V
T
A
= 25°C
Line Regulation (V
CC
= 2.5V to 40V, T
A
= 25°C)
Total Variation Over Line, and Temperature
V
FB2
= 1.25V
µA
µA
—
V
V
V
%/V
V
µA
Feedback Comparator 1
I
IB(FB1)
V
TH(FB2)
Input Bias Current
Threshold Voltage
Feedback Comparator 2
—
1.225
–0.4
0.008
1.25
0
0.03
1.275
0.4
%/V
V
µA
I
IB(FB2)
Input Bias Current
NOTES:
1. Maximum package power dissipation limits must be observed.
2. Low duty cycle pulse techniques are used during test to maintain junction temperature as close to ambient as possible.
3. T
LOW
= – 40°C T
HIGH
= +85°C
TC33163-1 5/16/00
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Power Switching Regulators
TC33163
ELECTRICAL CHARACTERISTICS:
V
CC
= 15V, Pin 16 = V
CC
, C
T
= 620pF, for typical values T
A
= 25°C, for
min/max values T
A
is the operating ambient temperature range that applies (Note 3), unless otherwise noted.
Symbol
Parameter
Test Conditions
T
A
= 25°C
Total Variation Over V
CC
= 2.5V
to 40V, and Temperature
V
LPK (SENSE)
= 15V
Min
—
230
—
Typ
250
—
1.0
Max
—
270
20
Units
mV
Current Limit Comparator
V
TH(LPK SENSE)
Threshold Voltage
I
IB(SENSE)
V
CE(SAT)
Input Bias Current
µA
V
Driver and Output Switch (Note 2)
Sink Saturation Voltage
I
SW
= 2.5A, Pins 14, 15 Grounded
Non-Darlington Connection
R
PIN9
= 110Ω to V
CC
, I
SW
/I
DRV
= 20
Darlington Connection
Pins 9, 10, 11 Connected
Collector Off-State Leakage Current V
CE
= 40V
Bootstrap Input Current Source
V
BS
= V
CC
+ 5.0V
Bootstrap Input Zener
I
Z
= 25mA
Clamp Voltage
Input Threshold
Input Hysteresis
Output Sink Saturation Voltage
Output Off-State Leakage Current
Standby Supply Current
V
FB2
Increasing
V
FB2
Decreasing
I
SINK
= 2.0mA
V
OH
= 15V
V
CC
= 2.5V to 40V, Pin 8 = V
CC,
Pins 6, 14, 15 = GND,
Remaining Pins Open
—
—
—
0.5
V
CC
+ 6.0
0.6
1.0
0.02
2.0
V
CC
+ 6.0
1.0
1.4
100
4.0
V
CC
+ 9.0
I
C(OFF)
I
SOURCE (DRV)
V
Z
µA
mA
V
Low Voltage Indicator
V
TH
V
H
V
OL(LVI)
I
OH
1.07
—
—
—
—
1.125
15
0.15
0.01
6.0
1.18
—
0.4
5.0
10
V
mV
V
µA
mA
Total Device
I
CC
NOTES:
1. Maximum package power dissipation limits must be observed.
2. Low duty cycle pulse techniques are used during test to maintain junction temperature as close to ambient as possible.
3. T
LOW
= – 40°C T
HIGH
= +85°C
TC33163-1 5/16/00
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Power Switching Regulators
TC33163
I
PK SENSE
R
SC
V
CC
Timing Capacitor
Shutdown
C
T
R
DT
GND
8
7
6
5
0.25V Current
– Limit
+ +
+
Oscillator
9
10
Driver Collector
Switch Collector
Q1
R
Q
S
Latch
+
Q2
12
60
13
14
45k
Switch Emitter
Feedback
Comparator
11
Thermal
GND
4
Voltage Feedback 1 3
Voltage Feedback 2 2
LVI Output 1
+
+
–
+
+
–
+
15
2.0mA
16 Bootstrap Input +
–
= Sink Only
Positive True Logic
LVI
1.25V15k
+
1.125V
+
7.0V
(Bottom View)
Figure 1. Representative Block Diagram
1
Comparator Output
0
1.25V
Timing Capacitor C
T
0.55V
1
Oscillator Output
0
On
Output Switch
Off
Nominal Output
Voltage Level
Output Voltage
t
9t
Startup
Quiescent Operation
Figure 2. Typical Operating Waveforms
TC33163-1 5/16/00
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Power Switching Regulators
TC33163
INTRODUCTION
The TC33163 series are monolithic power switching
regulators optimized for DC-to-DC converter applica-
tions. The combination of features in this series enables
the system designer to directly implement step-up, step-
down, and voltage-inverting converters with a minimum
number of external components. Potential applications
include cost sensitive consumer products as well as
equipment for the automotive, computer, and industrial
markets. A Representative Block Diagram is shown in
Figure 1.
This can be accomplished with the addition of an external
deadtime resistor (R
DT
) placed across C
T
. The resistor in-
creases the discharge current which reduces the on-time of
the output switch. A graph of the Output Switch On-Off Time
versus Oscillator Timing Capacitance for various values of
R
DT
is shown in Figure 11. Note that the maximum output duty
cycle, (t
ON
/t
ON
+ t
OFF
), remains constant for values of C
T
greater than 0.2nF. The converter output can be inhibited by
clamping C
T
to ground with an external NPN small-signal
transistor.
Feedback and Low Voltage Indicator Comparators
Output voltage control is established by the Feedback
comparator. The inverting input is internally biased at
1.25V and is not pinned out. The converter output voltage is
typically divided down with two external resistors and moni-
tored by the high impedance noninverting input at Pin 2. The
maximum input bias current is
±0.4µA,
which can cause an
output voltage error that is equal to the product of the input bias
current and the upper divider resistance value. For applica-
tions that require 5.0V, the converter output can be directly
connected to the noninverting input at Pin 3. The high imped-
ance input, Pin 2, must be grounded to prevent noise pickup.
The internal resistor divider is set for a nominal voltage of
5.05V. The additional 50mV compensates for a 1.0% voltage
drop in the cable and connector from the converter output to
the load. The Feedback comparator’s output state is con-
trolled by the highest voltage applied to either of the two
noninverting inputs.
The Low Voltage Indicator (LVI) comparator is designed
for use as a reset controller in microprocessor-based
systems. The inverting input is internally biased at 1.125V,
which sets the noninverting input thresholds to 90% of nomi-
nal. The LVI comparator has 15mV of hysteresis to prevent
erratic reset operation. The Open Collector output is capable
of sinking in excess of 6.0mA (see Figure 20). An external
resistor (R
LVI
) and capacitor (C
DLY
) can be used to program
a reset delay time (t
DLY
) by the formula shown below, where
V
TH(MPU)
is the microprocessor reset input threshold. Refer to
Figure 3.
t
DLY
= R
LVI
C
DLY
In
OPERATING DESCRIPTION
The TC33163 operates as a fixed on-time, variable
off-time voltage mode ripple regulator. In general, this
mode of operation is somewhat analogous to a capacitor
charge pump and does not require dominant pole loop
compensation for converter stability. The Typical Operat-
ing Waveforms are shown in Figure 2. The output voltage
waveform shown is for a step-down converter with the
ripple and phasing exaggerated for clarity. During initial
converter startup, the feedback comparator senses that
the output voltage level is below nominal. This causes the
output switch to turn on and off at a frequency and duty
cycle controlled by the oscillator, thus pumping up the
output filter capacitor. When the output voltage level
reaches nominal, the feedback comparator sets the latch,
immediately terminating switch conduction. The feed-
back comparator will inhibit the switch until the load
current causes the output voltage to fall below nominal.
Under these conditions, output switch conduction can be
inhibited for a partial oscillator cycle, a partial cycle plus a
complete cycle, multiple cycles, or a partial cycle plus
multiple cycles.
Oscillator
The oscillator frequency and on-time of the output
switch are programmed by the value selected for timing
capacitor C
T
. Capacitor C
T
is charged and discharged by
a 9 to 1 ratio internal current source and sink, generating
a negative going sawtooth waveform at Pin 6. As C
T
charges, an internal pulse is generated at the oscillator
output. This pulse is connected to the NOR gate center
input, preventing output switch conduction, and to the
AND gate upper input, allowing the latch to be reset if the
comparator output is low. Thus, the output switch is
always disabled during ramp-up and can be enabled by
the comparator output only at the start of ramp-down. The
oscillator peak and valley thresholds are 1.25V and 0.55V,
respectively, with a charge current of 225µA and a dis-
charge current of 25µA, yielding a maximum on-time duty
cycle of 90%. A reduction of the maximum duty cycle may
TC33163-1 5/16/00
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1
1–
V
TH (MPU)
V
OUT
Current Limit Comparator,Latch and Thermal Shutdown
With a voltage mode ripple converter operating under
normal conditions, output switch conduction is initiated by the
oscillator and terminated by the Voltage Feedback compara-
tor. Abnormal operating conditions occur when the converter
output is overloaded or when feedback voltage sensing is lost.
Under these conditions, the Current Limit comparator will
protect the Output Switch.
5
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