AIC1652
MICROPOWER INVERTING DC/DC CONVERTER
SPEC NO: DS-1652-01
!
!
FEATURES
The AIC1652 is a high performance inverting
DC/DC converter, designed to drive an external
power switch to generate programmable negative
voltages. In the particularly suitable LCD bias
contrast application, efficiency of 87% can be
achieved with low cost PNP bipolar transistor
drivers. Output voltage can be scaled to -40V or
greater by two external resistors. A pulse frequency modulation scheme is employed to
maintain high efficiency conversion under wide
input voltage range. Quiescent current is about
80µA and can be reduced to 0.7µA in shutdown
mode. Switching frequency being around 70KHz
to 160KHz range, small size switching components are ideal for battery powered portable
equipments, like notebook and palmtop computers.
2.4V to 7V Input Voltage Operation.
Adjustable Output Voltage up to -40V.
Low Quiescent Current at 80µA.
Pulse Frequency Modulation Maintains High
Efficiency (87%).
70KHz to 160KHz Switching Frequency.
Power-Saving Shutdown Mode (0.7µA Typical).
High Efficiency with Low Cost External PNP
Bipolar Transistor.
"
"
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"
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!
"
"
!
DESCRIPTION
APPLICATIONS
Negative LCD Contrast Bias for
1. Notebook & Palmtop Computers.
2. Pen-Based Data System.
3. Portable Data Collection Terminals.
4. Personal Digital Assistants.
Negative Voltage Supply.
TYPICAL APPLICATION CIRCUIT
VIN
2.4V ~ 7V
CL
VIN
100µF +
C1
VREF
DHI
AIC1652
DLOW
SHDN
FB
0.047µF
C4
R2
Q1
9012
D1
RB
1N5819
470~1.8K
GND
150µH
*L
C2
100µF
VOUT
-12V~ -40V
-10mA
+
R1
1M
C3
100K
*
Sumida CD-54 Series
VOUT = -1.22V x R1/R2
10nF
Negative LCD Contrast Bias Power Supply
!
ORDERING INFORMATION
AIC1652 XX
PIN CONFIGURATION
ORDER NUMBER
PACKAGE TYPE
N: PLASTIC DIP
S: SMALL OUTLINE
TEMPERATURE RANGE
C=0°C~+70°C
TOP VIEW
AIC1652CN
(PLASTIC DIP)
AIC1652CS
(PLASTIC SO)
CL
VIN
1
8
VREF
2
7
DHI
SHDN
3
6
DLOW
FB
4
5
GND
ANALOG INTEGRATIONS CORPORATION
www.analog.com.tw
4F, 9 Industry E. 9th Road, Science-based Industrial Park , Hsinchu, Taiwan, R.O.C.
TEL: (8863)577-2500 FAX:(8863)577-2510
1
AIC1652
MICROPOWER INVERTING DC/DC CONVERTER
SPEC NO: DS-1652-01
!
ABSOLUTE MAXIMUM RATINGS
Supply Voltage ..................................................................…………………............ 7V
SHDN Voltage ...............................................……………..................................... 7V
Operation Temperature Range ................................……….......................... 0°C~70°C
Storage Temperature Range .................................…………................. -65°C~ 150°C
!
TEST CIRCUIT
Refer to Typical Application Circuit.
!
ELECTRICAL CHARACTERISTICS
PARAMETER
(VIN=5V, Ta=25°°C, unless otherwise specified.)
TEST CONDITIONS
TYP.
MAX.
UNIT
7
V
80
150
µA
1.22
1.28
V
2.4
Input Voltage
Switch Off Current
VFB=-50mV
VREF Voltage
ISOURCE = 250µA
1.16
µA
250
VREF Source Current
DLOW “ON Resistance”
5
Ω
DHI “ON Resistance”
7
Ω
CL Threshold
70
mV
0.8
Shutdown Threshold
V SHDN = 0V
Shutdown Mode Current
!
MIN.
1.5
2.4
V
0.7
2
µA
TYPICAL PERFORMANCE CHARACTERISTICS
Shutdown Current vs VIN
VREF Source Current vs VIN
1.5
350
Shutdown Current (µA)
Source Current (µA)
300
250
200
150
100
1
0.5
50
0
0
2
3
4
5
6
VIN (V)
7
8
1
2
3
4
5
6
7
8
VIN (V)
ANALOG INTEGRATIONS CORPORATION
www.analog.com.tw
4F, 9 Industry E. 9th Road, Science-based Industrial Park , Hsinchu, Taiwan, R.O.C.
TEL: (8863)577-2500 FAX:(8863)577-2510
2
AIC1652
MICROPOWER INVERTING DC/DC CONVERTER
SPEC NO: DS-1652-01
TYPICAL PERFORMANCE CHARACTERISTICS
(CONTINUED)
Frequency vs VIN Voltage
150
100
130
95
Duty Cycle (%)
Frequency (KHz)
!
110
Ta=0°C
90
Ta=25°C
Duty Cycle vs VIN Voltage
Ta=0°C
Ta=25°C
90
Ta=70°C
85
70
Ta=70°C
50
80
2
3
4
5
6
7
2
VIN (V)
!
3
4
5
6
7
VIN (V)
BLOCK DIAGRAM
CURRENT LIMIT
COMPARATOR
+
1
VIN
VIN
60mV
8
CL
VREF
2
3
SHDN
PFM
OSCILLATOR
VIN
1.22V
REFERENCE
VOLTAGE
DHI
OUTPUT DRIVER
6
DLOW
+
4
5
-
FB
7
LATCH
GND
ERROR COMPARATOR
!
PIN DESCRIPTIONS
PIN 1: VIN
- 2.4V to 7V input supply voltage.
PIN 2: VREF - 1.22V reference output. Bypass
with a 0.047µF capacitor to GND.
Sourcing capability is guaranteed to
be greater than 250µA.
PIN 3: SHDN- Logic input to shutdown the chip.
>1.5V = normal operation,
GND = shutdown
In shutdown mode DLOW and DHI
pins are at high level.
PIN 4: FB
- Feedback signal input to sense
ground. Connecting a resistor R1 to
VOUT and a resistor R2 to VREF pin
yields the output voltage:
VOUT = -(R1/R2 ) x VREF
PIN 6: DLOW - Driver sinking output. Connected to
DHI when using an external Pchannel MOSFET. When using an
external PNP bipolar transistor,
connect a resistor RB from this pin
to DHI. RB value depends on VIN,
inductor and PNP bipolar transistor.
By adjusting the RB value, efficiency can be optimized.
PIN 7: DHI
- Driver sourcing output. Connect to
gate of the external P-channel
MOSFET or base of the PNP bipolar transistor.
PIN 8: CL
- Current-limit input. This pin clamps
the switch peak current to prevent
over-current damage to the external
switch.
PIN 5: GND - Power ground.
ANALOG INTEGRATIONS CORPORATION
www.analog.com.tw
4F, 9 Industry E. 9th Road, Science-based Industrial Park , Hsinchu, Taiwan, R.O.C.
TEL: (8863)577-2500 FAX:(8863)577-2510
3
AIC1652
MICROPOWER INVERTING DC/DC CONVERTER
SPEC NO: DS-1652-01
!
APPLICATION INFORMATIONS
180µH
The typical application circuit generates an adjustable
negative voltage for contrast bias of LCD displays. Efficiency and output power can be optimized by using appropriate inductor and switch. The following formulas
provide a guideline for determining the optimal component values:
V IN
L
= (11.1 − 0.15 × V IN) ×
I OUT × V OUT
220µH
PNP :
Max. Output Power vs VIN
0.8
Typical Application Circuit
Max. Output Power (W)
100µH
0.6
120µH
150µH
0.4
I C,MAX ≥ 200 ×
0.2
0
2
4
6
I OUT
V IN
IOUT
V IN
V CE < 0. 4V at I C = 200 ×
8
and β = 10
RB ≅ 3 x L x (VIN - 0.8)
where, units: VIN & VOUT in V, IOUT in A, L in µH,
RB in Ω
VIN (V)
!
V CEO > V IN + V OUT
Inductor Value
APPLICATION EXAMPLES
Efficiency vs Load Current
90
Efficiency vs VIN
90
VOUT = -15V
L
=150µH
Efficiency (%)
Efficiency (%)
VIN =7V
VIN=5V
85
VOUT =-15V
IOUT =-10mA
88
VIN=3V
80
75
L=220µH
86
84
L=150µH
82
L=100µH
80
70
0
5
10
15
20
25
2
30
3
4
6
7
8
Efficiency vs VIN
Efficiency vs Load Current
90
90
VOUT =-22V
L
=120µH
VOUT =-22V
IOUT =-10mA
88
VIN=7V
85
VIN=5V
Efficiency (%)
Efficiency (%)
5
VIN (V)
Load Current (mA)
VIN=3V
80
75
L=220µH
86
L=150µH
84
L=100µH
82
80
70
0
5
10
15
20
25
30
2
3
4
5
6
7
8
VIN (V)
Load Current (mA)
ANALOG INTEGRATIONS CORPORATION
www.analog.com.tw
4F, 9 Industry E. 9th Road, Science-based Industrial Park , Hsinchu, Taiwan, R.O.C.
TEL: (8863)577-2500 FAX:(8863)577-2510
4
AIC1652
MICROPOWER INVERTING DC/DC CONVERTER
SPEC NO: DS-1652-01
!
TYPICAL EXAMPLE
(CONTINUED)
Efficiency vs VIN
Efficiency vs Load Current
90
90
VOUT =-30V
L
=100µH
VIN=7V
VOUT =-30V
IOUT =-10mA
88
VIN=5V
80
Efficiency (%)
Efficiency (%)
85
VIN=3V
L=150µH
86
L=120µH
84
75
82
L=100µH
80
70
0
5
10
15
20
25
30
2
3
Load Current (mA)
!
4
5
6
7
8
VIN (V)
PHYSICAL DIMENSIONS
"
8 LEAD PLASTIC SO (unit: mm)
D
SYMBOL
MIN
MAX
A
1.35
1.75
A1
0.10
0.25
B
0.33
0.51
C
0.19
0.25
D
4.80
5.00
E
3.80
4.00
H
E
e
e
A
A1
C
B
1.27(TYP)
H
5.80
6.20
L
0.40
1.27
L
ANALOG INTEGRATIONS CORPORATION
www.analog.com.tw
4F, 9 Industry E. 9th Road, Science-based Industrial Park , Hsinchu, Taiwan, R.O.C.
TEL: (8863)577-2500 FAX:(8863)577-2510
5
AIC1652
MICROPOWER INVERTING DC/DC CONVERTER
SPEC NO: DS-1652-01
"
8 LEAD PLASTIC DIP (unit: mm)
D
SYMBOL
MIN
MAX
A1
0.381
—
A2
2.92
4.96
b
0.35
0.56
C
0.20
0.36
D
9.01
10.16
E
7.62
8.26
E1
6.09
7.12
E1
E
A2
A1
C
L
e
eB
b
e
2.54 (TYP)
eB
—
10.92
L
2.92
3.81
UNIT: mm
ANALOG INTEGRATIONS CORPORATION
www.analog.com.tw
4F, 9 Industry E. 9th Road, Science-based Industrial Park , Hsinchu, Taiwan, R.O.C.
TEL: (8863)577-2500 FAX:(8863)577-2510
6