TOKO TK11830M

TK11830
POSITIVE-TO-NEGATIVE DC-DC CONVERTER
FEATURES
APPLICATIONS
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■
■
■
■
■
■
■
■
■
Positive-to-Negative Converter
Adjustable Output Voltage
On/Off Control
Thermal Protection Sensor
Broad Operating Voltage Range
Miniature Package (SOT-23L)
Pagers
Cassette Recorders
Cordless Telephones
Portable Instrumentation
Radio Control Systems
Battery Operated Equipment
Local Area Network (LAN) Receivers
DESCRIPTION
The TK11830 is a positive-to-negative DC-DC converter.
This IC converts a positive input voltage into a regulated
negative output voltage. This DC-DC converter features
an On/Off function with an active low control. The internal
voltage reference provides a stable output voltage which
can be set from -0.5 to -12.5 V. The thermal protection
feature provides oscillator shutdown in the event of an
overload condition. The wide input voltage range of 2.5 to
15 V and a 60 mA output current capability allow flexible
operation in a large number of applications.
TK11830
Vref
VFB
CONTROL
GND
20 P
VOSC
VIN
The TK11830 is available in a miniature SOT-23L surface
mount package. Optimized Toko inductors are available.
ORDERING INFORMATION
TK11830M
BLOCK DIAGRAM
GND
VFB
VOSC
Tape/Reel Code
THERMAL
PROTECTION
TAPE/REEL CODE
COMP
TL: Tape Left
OSCILLATOR
CONTROL
REFERENCE
VOLTAGE
Vref
January 1999 TOKO, Inc.
CONTROL
VIN
Page 1
TK11830
ABSOLUTE MAXIMUM RATINGS
Supply Voltage ......................................................... 16 V
Operating Voltage ............................................ Min. 2.5 V
Power Dissipation (Note 1) ................................ 400 mW
Storage Temperature Range ................... -55 to +150 °C
Operating Temperature Range ...................-20 to +75 °C
Junction Temperature ........................................... 150 °C
Lead Soldering Temperature (10 s) ...................... 235 °C
TK11830 ELECTRICAL CHARACTERISTICS
Test Conditions: VIN = 5 V, L = 470 µH, TA = 25 °C, unless otherwise specified.
SYMBOL
PARAMETER
TEST CONDITIONS
VIN + |VOUT| ≤16 V
MI N
TYP
2.5
MAX
UNITS
15
V
1.33
V
VIN
Input Voltage
Vref
Reference Voltage
∆Vref
Temperature Coefficient of
Reference Voltage
TA = -30 to +80 ° C
IIN(OFF)
Input Current at Shutdown
RCONT = 300 kΩ, Output OFF,
VIN = 5 V
25
100
µA
Line Reg
Line Regulation
VIN = 2.5 to 10 V, VOUT = -5 V,
IOUT = 20 mA
10
50
mV
Load Reg
Load Regulation
VOUT = -5 V, IOUT = 1 to 50 mA
20
100
mV
IOUT
Output Current
VOUT = -5 V
1.23
1.28
mV/° C
±0.1
50
60
mA
ON/OFF CONTROL TERMINAL
VCONT = 0.4 V, RCONT = 300 kΩ
ICONT
Control Terminal Current
VCONT(ON)
Control Voltage (ON)
RCONT = 300 kΩ, Output ON
VCONT(OFF)
Control Voltage (OFF)
RCONT = 300 kΩ, Output OFF
0.2
VCONT = 5.0 V, RCONT = 300 kΩ
3.0
µA
0.4
2.2
µA
V
V
Note 1: Power dissipation is 400 mW (internally limited) when mounted as recommended. Derate at 3.2 mW/°C for operation above 25 °C.
Gen Note: Output capacitor should have low ESR at reduced temperatures if used below 0 °C.
Gen Note: Parameters with min. or max. values are 100% tested at TA = 25 °C.
Page 2
January 1999 TOKO, Inc.
TK11830
TEST CIRCUIT
Cref
1 µF
Note: Toko Inductor (470 µH): 646CY-471M
or 636CE-471K (D73C)
VOUT = (Vref / 5) x [ 1-4 x (R2 / R1)],
where Vref = 1.28 V
Vref
R1
20 k
Note: If a noise filter is desired, select:
RF = (50 to 150 mV) / IOUT,
where IOUT = Load Current
VFB
RCONT CONTROL
GND
CFB
0.1 µF
300 kΩ
VOSC
SD
VCONT
(ON/OFF)
VIN
R2
103 KΩ
RF
VOUT
VO
+VIN
+
CIN
47 µF
L
+
COUT
47 µF
CF
GND
GND
TYPICAL PERFORMANCE CHARACTERISTICS
OUTPUT VOLTAGE VS.
LOAD CURRENT
VOUT = -3 V
VIN = 3 V
-2.8
VIN = 5 V
-2.7
0
20
40
60
80
-4.9
50
EFFICIENCY
-4.8
-4.7
-4.6
100
0
6
12
24
30
ILOAD (mA)
OUTPUT VOLTAGE VS.
LOAD CURRENT
OUTPUT VOLTAGE AND EFFICIENCY
VS. LOAD CURRENT
VOUT = -5 V
VIN = 5 V
-5.1
VOUT = -5 V
VOUT
100
VOUT (V)
-4.9
VIN = 3 V
VIN = 5 V
-4.8
VIN = 8 V
-4.7
0
20
40
60
ILOAD (mA)
January 1999 TOKO, Inc.
80
100
-4.9
50
EFFICIENCY
-4.8
EFF (%)
-5.0
-5.0
VOUT (V)
18
ILOAD (mA)
-5.1
-4.6
100
-5.0
VOUT (V)
-2.9
-2.6
VOUT
VIN = 8 V
-3.0
VOUT = -5 V
VIN = 3 V
-5.1
EFF (%)
-3.1
VOUT (V)
OUTPUT VOLTAGE AND EFFICIENCY
VS. LOAD CURRENT
-4.7
-4.6
0
10
20
30
40
50
ILOAD (mA)
Page 3
TK11830
TYPICAL PERFORMANCE CHARACTERISTICS (CONT.)
OUTPUT VOLTAGE AND EFFICIENCY
VS. LOAD CURRENT
OUTPUT VOLTAGE VS.
LOAD CURRENT
VOUT = -10 V
-10.0
VOUT = -5 V
VIN = 10 V
-5.1
VOUT
VOUT (V)
VIN = 5 V
-9.7
0
20
40
60
80
-4.6
100
60
80
100
OUTPUT VOLTAGE AND EFFICIENCY
VS. INPUT VOLTAGE
TA = -50 °C
VOUT = -5 °V
TA = -50 °C
-5.1
100
-4.9
VIN = 3 V
VIN = 5 V
-4.8
VIN = 8 V
0
20
40
60
80
ILOAD = 20 mA
-4.9
50
ILOAD = 10 mA
-4.8
EFFICIENCY
-4.7
-4.6
100
0
4
8
12
16
20
ILOAD (mA)
VIN (V)
OUTPUT VOLTAGE VS.
LOAD CURRENT
OUTPUT VOLTAGE AND EFFICIENCY
VS. INPUT VOLTAGE
TA = 25 °C
VOUT = -5 °V
-5.1
EFF (%)
-5.0
VOUT (V)
VOUT (V)
40
OUTPUT VOLTAGE VS.
LOAD CURRENT
-4.7
TA = 25 °C
-5.1
-5.0
100
-5.0
-4.9
VOUT (V)
VOUT (V)
20
ILOAD (mA)
-5.0
VIN = 3 V
VIN = 5 V
-4.8
VIN = 8 V
-4.7
0
20
40
60
ILOAD (mA)
Page 4
0
ILOAD (mA)
-5.1
-4.6
50
EFFICIENCY
-4.8
-4.7
-9.6
-4.6
-4.9
80
100
ILOAD = 20 mA
-4.9
50
-4.8
EFFICIENCY
ILOAD = 10 mA
-4.7
-4.6
EFF (%)
VOUT (V)
VIN = 3 V
-9.8
EFF (%)
-5.0
-9.9
-9.5
100
0
4
8
12
16
20
VIN (V)
January 1999 TOKO, Inc.
TK11830
TYPICAL PERFORMANCE CHARACTERISTICS (CONT.)
OUTPUT VOLTAGE VS.
LOAD CURRENT
OUTPUT VOLTAGE AND EFFICIENCY
VS. INPUT VOLTAGE
TA = 85 °C
VOUT = -5 °V
-5.1
VIN = 3 V
VIN = 5 V
-4.8
VIN = 8 V
0
20
40
60
80
50
EFFICIENCY
-4.8
-4.7
-4.6
100
0
4
8
12
16
20
ILOAD (mA)
VIN (V)
OUTPUT VOLTAGE VS.
INPUT VOLTAGE
INPUT CURRENT (SHUTDOWN)
VS. INPUT VOLTAGE
TA = -50 °C
ILOAD = 0 mA, 10 mA, 20 mA
-5.1
ILOAD = 20 mA
-4.9
EFF (%)
-4.9
-4.7
100
IOFF
-5.0
80
IIN(OFF) (µA)
VOUT (V)
100
-5.0
VOUT (V)
VOUT (V)
-5.0
-4.6
TA = 85 °C
-5.1
-4.9
-4.8
VIN
CONTROL
VIN
60
1
40
2
RCONT
300 k
1.0 V
-4.7
0
1
2
3
4
0
5
12
16
20
OUTPUT VOLTAGE AND CONTROL
CURRENT VS. CONTROL VOLTAGE
5
-5
VOUT
-4
VOUT (V)
VOUT (V)
8
OUTPUT VOLTAGE VS.
INPUT VOLTAGE
-5.0
-4.9
-4.8
-3
TA = 25 °C
3
-2
TA = -50 °C
2
0
0
1
2
3
VIN (V)
January 1999 TOKO, Inc.
4
5
VIN
4
TA = 85 °C
1
-1
-4.7
-4.6
4
VIN (V)
TA = 25 °C
ILOAD = 0 mA, 10 mA, 20 mA
-5.1
0
VIN (V)
ICONT (µA)
-4.6
20
VOUT
CONTROL
ICONT
RCONT
300 k
VCONT
0
0
0.4
0.8
1.2
1.6
2.0
VCONT (V)
Page 5
TK11830
TYPICAL PERFORMANCE CHARACTERISTICS (CONT.)
OUTPUT VOLTAGE VS.
INPUT VOLTAGE
OUTPUT VOLTAGE AMD CONTROL
VOLTAGE VS. CONTROL CURRENT
-5.0
TA = 85 °C
-4.9
-4.8
1.0
VOUT
-4
VOUT (V)
VOUT (V)
TA = 25 °C
-5
VIN
-3
0.5
-2
VOUT
CONTROL
VCONT (V)
ILOAD = 0 mA, 10 mA, 20 mA
-5.1
ICONT
-4.7
-4.6
-1
0
1
2
3
4
0
5
0
1
2
3
4
VIN (V)
ICONT (µA)
REFERENCE VOLTAGE VS.
INPUT VOLTAGE
REFERENCE VOLTAGE VS.
AMBIENT TEMPERATURE
1.29
5
1.30
Vref (V)
Vref (V)
1.29
1.28
1.28
1.27
1.26
1.27
0
3
6
9
VIN (V)
Page 6
12
15
1.25
-50
0
50
100
TA (°C)
January 1999 TOKO, Inc.
TK11830
CIRCUIT OPERATION
The TK11830 operates with a continuous mode oscillator. The circuit operates by detecting the difference between the
set output voltage and the internal bandgap reference. This is used to vary the oscillator frequency in response to load
current. The output voltage is regulated by controlling the power transistor switch current; this maintains a constant
charge on the output capacitor.
Inductor Voltage
AAA
AA
~VIN
~VOUT
Absolute Output
Voltage
Inductor Current
Frequency goes up when the load current goes down.
ILPK(MAX)
Power - Transistor Maximum
AAAAAAAAAAAAAA
A
A
A A
Low Load
Current
Set Output Voltage
High Load
Current
Start
Time
January 1999 TOKO, Inc.
Page 7
TK11830
CIRCUIT OPERATION (CONT.)
POLARITY-INVERTING OPERATION
VSAT
VSAT
VF
IL
IC
ILOAD
VL
Power Transistor Saturation Voltage
Diode Forward Voltage Drop
Inductor Current
Capacitor Current
Load Current
Inductor Voltage
VF
ILOAD
VOUT
VIN
IL
OSCILLATOR
CONTROL
IC
L
COUT
+
where:
VL = L x (diL / dt) and VL = a constant value: IL = (VL / L) x t
INDUCTOR VOLTAGE
VIN - VSAT
During the charge cycle:
ILPK = [(VIN - VSAT) x tON] / L
ON
-(|VOUT| + VF)
OFF
(1)
During the discharge cycle:
ILPK = [(|VOFF| + VF) x tOFF] / L
(IL = 0 after tOFF)
IL
(2)
ILPK
From (1) and (2):
tON
tON / tOFF = (|VOUT| + VF) / (VIN - VSAT)
CHARGE
When IL = IC + ILOAD and output voltage are in a steady
state, the change of the charge/discharge must be
equivalent, so:
∆Q+ = ∆Q1- + ∆Q2And:
CAPACITOR CURRENT
(3)
tOFF
DISCHARGE
ILPK - ILOAD
IC
∆Q+
∆Q2ILOAD
∆Q1-
ILPK = 2 x ILOAD x [(tON / tOFF) + 1]
Ripple Voltage:
VRIPPLE = ∆Q+ / COUT
= (ILPK - ILOAD)2 x tOFF / 2COUT x ILPK
~ ILOAD x tON / COUT
RIPPLE VOLTAGE
(4)
VRIPPLE
(5)
Page 8
January 1999 TOKO, Inc.
TK11830
CIRCUIT OPERATION (CONT.)
Oscillator Frequency:
The ESR of the capacitor and the effect of the input voltage
difference for the comparator function are added to VRIPPLE.
The maximum inductor current is limited by the power
transistor switch capacity: ILPK(MAX) ~ 300 mA.
f = 1/(tON + tOFF)
Where:
Output Voltage is as follows:
tON = L x [ILPK / (VIN - VSAT)]
VOUT = (Vref / 5) x (1 - 4 x R2 / R1)
And:
tOFF = L x [ILPK / (|VOUT| + VF)]
where: Vref = 1.28 V
R3, R4: IC Internal
R4 / R3 = 1 / 4
R1, R2 : External Resistor
Therefore:
f=
1


1
1
I LPK L × 
+

 VIN − VSAT VOUT + VF 
Vref
R3
=
(VIN − VSAT )2 ( VOUT
+ VF )
2I LOAD (VIN − VSAT + VOUT + VF )
2
×
1
L
R1
R4
R2
VOUT
tON / tOFF
(|VOUT| + VF) / (VIN - VSAT)
ILPK
2 x ILOAD x [(tON / tOFF) + 1]
f
COUT
(VIN − VSAT )2 ( VOUT
+ VF )
2I LOAD (VIN − VSAT + VOUT + VF )
2
•
1
L
(ILOAD x tON) / VRIPPLE
January 1999 TOKO, Inc.
Page 9
TK11830
APPLICATION INFORMATION
COMPONENT REQUIREMENTS
Control Pin Resistor (RCONT)
Inductor
DC resistance of the inductor must be less than 5 Ω. For
optimal performance and efficiency, an inductor with a DC
resistance of less than 1 Ω is recommended. The oscillator
frequency is inversely proportional to inductance. The
inductance should be greater than 300 µH to prevent loss
of efficiency at high frequencies.
Input requirements of the Control pin are as follows:
RCONT
VCONT
+
30 k
VBE
ICONT
There is a large peak current (up to ILPK = 300mA) when
the inductor is saturated.
ILPK
ILPK(MAX)
-300 mA
IL
INDUCTOR
SATURATION
t
When VCONT is high (above 2.2 V), the circuit operation is
stopped. When VCONT is low (below 0.4 V), operation is
resumed.
t
CFB, CREF, CIN, COUT
A control current of 3 µA (typ.) is required for shutdown.
Shutdown voltage, VCONT, is related to the resistance
RCONT as shown below. VCONT changes when RCONT is
changed.
The filtered output ripple is fed back to the feedback pin. To
ensure continuous operation, CFB should be connected
between the feedback pin and ground. If a large voltage is
fed back to the feedback pin, the power transistor switch
drive will be intermittent. This causes a large ripple voltage
since ILPK becomes larger. The value of CFB is determined
by the value of the output capacitor, COUT, and the feedback
resistance, R2. The feedback capacitor must be larger
when the ripple voltage is high due to the lower COUT. CREF
is used to prevent oscillation of the band gap reference and
to stabilize the feedback loop. The input capacitor, CIN, is
used to reduce supply impedance and to provide sufficient
input current during switching for stable circuit operation.
VCONT ~ RCONT x ICONT + VBE
VCONT ~ (300 kΩ) x (3 µA) + 0.7 V = 1.60 V at
RSD = 300 kΩ and VBE ~ 0.7 V
ON/OFF CONTROL
TA = 25 °C
-5
5
4
-3
3
-2
2
CIN > 22 µF
-1
1
COUT > 22 µF
0
Recommended values:
CREF > 0.1 µF
CFB > 0.01 µF
Note: COUT should be sufficiently large and have a low
VOUT (V)
-4
ICONT (µA)
L(LARGE)
L(SMALL)
0
0
1
2
VCONT
ESR to minimize ripple voltage.
Page 10
January 1999 TOKO, Inc.
TK11830
APPLICATION INFORMATION (CONT.)
mounting. The package power dissipation curve on a
printed circuit board is estimated as follows:
INTERMITTENT OSCILLATION
INDUCTOR CURRENT
When the ripple voltage applied to the feedback pin is large
and CFB is small, the power transistor switch drive is large
and the output voltage exceeds the desired value. This
causes the oscillator to stop for a period of ti. When the
ripple voltage is large and the power transistor is driven at
maximum capacity, a current up to ILPK(MAX) goes through
the inductor.
ILPK(MAX)
PLOSS, must be within this curve. The efficiency, E (%), is
the ratio between input and output power when the dc-dc
converter is operating.
IL
tON
tOFF
When Pin 4 is connected to GND (Power transistor switch
is at maximum conductance), all input power is dissipated
by the IC at TA = room temperature. In this state Tj goes up
to 150 °C and thermal protection operates. Input power is
defined as PIN = VIN x <IIN>, where <IIN> is the average of
input current. From Tj = Oja x P + TA and Tj = 150 °C.
P = PIN, TA = Room temp., Oja can be found. The power
dissipation curve shows the effect of mounting on thermal
characteristics.
ti
CAPACITOR CURRENT
ILPK(MAX)
-ILOAD
IC
PLOSS = PIN - POUT
∆Q+
∆Q1-
= POUT x [(100 / E) - 1]
ILOAD
∆Q2-
= |VOUT| x ILOAD x [(100 / E) - 1]
t
Note: tON/tOFF = (|VOUT| + VF) / (VIN - VSAT)
IIN
tON = [ILPK(MAX) / (VIN - VSAT)] x L
VIN
tOFF = [ILPK(MAX) / (|VOUT| + VF)] x L
Vref
VIN
+
VOSC
VFB
+
Since the charge of the capacitor is equivalent to the
discharge (∆Q+ = ∆Q1- + ∆Q2-):
ILPK(MAX) = 2 x ILOAD x [(tON / tOFF) + 1] + 2 x ILOAD x (ti / tOFF)
ti = ([ILPK(MAX) / (2 x ILOAD)] x tOFF) - (tON + tOFF)
f = 1 / (tON + tOFF + ti)
TA = 25 °C
MOUNTED ON PCB
When load current increases, ti becomes shorter.
As in the case above, if the load current is too small, the
power transistor becomes overdriven and intermittent
oscillation will occur.
IIN
<IIN>
PACKAGE POWER DISSIPATION
The internal thermal protection circuit will operate when Tj
is approximately 150 °C. When thermal protection operates,
the power transistor switch will cycle between on and off to
keep Tj ≤ 150 °C. Thermal resistance Oja is determined by
January 1999 TOKO, Inc.
t
IIN WAVEFORM WHEN THERMAL PROTECTION IS
OPERATING
Page 11
TK11830
APPLICATION INFORMATION (CONT.)
The components shown in the test circuit may be changed
for different operating conditions (input/output voltage,
output current, inductor type, etc.) The performance of the
DC-DC converter depends largely on the coil in use. To
optimize efficiency, a coil with a low DC resistance should
be used, such as the Toko 646CY471M. Oscillation will
begin with an inductor value as low as 100 µH. However,
if the Equivalent Series Resistance (ESR) is over 5 Ω,
oscillation may not occur. The input and output capacitors
should have a low ESR and high capacity since there is a
large ripple current present. For operation below 0 °C, the
capacitors should be selected for low ESR and good
temperature stability at reduced temperatures. This is
required to minimize ripple current. For low values of load
current, a smaller coil can be used. For higher current, a
large coil is needed to prevent saturation. When the coil
saturates, the current increases dramatically, resulting in
a severe overcurrent through the inductor. Please refer to
the following drawings.
PD (mW)
Tj = 150 °C
25
50
75
TA (°C)
150
750
MOUNTED
PD (mW)
600
450
FREE AIR
300
INDUCTOR CURRENT WAVEFORM
(NORMAL)
INDUCTOR CURRENT
150
0
0
50
100
150
TA (°C)
V OU T
+
OU T
11830
C OU T
R2
Di
6
5
4
0 .0 1
TK1 1 8 3 0
C REF
1
2
3
+
1 µF
C IN
ON /OFF
RS D
300 k
V IN
GN D
INDUCTOR CURRENT WAVEFORM
(SATURATED INDUCTOR)
INDUCTOR CURRENT
L
C FB
R1
23.0 mm
TIME
17.5 mm
TIME
Page 12
January 1999 TOKO, Inc.
TK11830
PACKAGE OUTLINE
Marking Information
SOT-23L (SOT-23L-6)
TK11830
Marking
N0
0.6
6
5
4
e1 3.0
1.0
Marking
1
2
3
0.32
e
+0.15
- 0.05
0.1
e 0.95
M
e 0.95
e
0.95
3.5
0.95
Recommended Mount Pad
+0.3
- 0.1
2.2
max
15
1.2
0.4
0.15
0.1
+0.15
- 0.05
0 - 0.1
1.4 max
0.3
(3.4)
+ 0.3
3.3
Dimensions are shown in millimeters
Tolerance: x.x = ± 0.2 mm (unless otherwise specified)
Toko America, Inc. Headquarters
1250 Feehanville Drive, Mount Prospect, Illinois 60056
Tel: (847) 297-0070
Fax: (847) 699-7864
TOKO AMERICA REGIONAL OFFICES
Midwest Regional Office
Toko America, Inc.
1250 Feehanville Drive
Mount Prospect, IL 60056
Tel: (847) 297-0070
Fax: (847) 699-7864
Western Regional Office
Toko America, Inc.
2480 North First Street , Suite 260
San Jose, CA 95131
Tel: (408) 432-8281
Fax: (408) 943-9790
Eastern Regional Office
Toko America, Inc.
107 Mill Plain Road
Danbury, CT 06811
Tel: (203) 748-6871
Fax: (203) 797-1223
Semiconductor Technical Support
Toko Design Center
4755 Forge Road
Colorado Springs, CO 80907
Tel: (719) 528-2200
Fax: (719) 528-2375
Visit our Internet site at http://www.tokoam.com
The information furnished by TOKO, Inc. is believed to be accurate and reliable. However, TOKO reserves the right to make changes or improvements in the design, specification or manufacture of its
products without further notice. TOKO does not assume any liability arising from the application or use of any product or circuit described herein, nor for any infringements of patents or other rights of
third parties which may result from the use of its products. No license is granted by implication or otherwise under any patent or patent rights of TOKO, Inc.
January 1999 TOKO, Inc.
© 1999 Toko, Inc.
All Rights Reserved
Page 13
IC-140-TK11830
0798O0.0K
Printed in the USA