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SS6652
Micro-Power Inverting DC/DC Controller
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FEATURES
2.4V to 7V input voltage operation. Adjustable output voltage up to -40V. Low quiescent current at 80A. Pulse frequency modulation maintains high efficiency (87%). 70KHz to 160KHz switching frequency. Power-saving shutdown mode (0.7A typical). High efficiency with low cost external Pchannel MOSFET or PNP bipolar transistor.
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DESCRIPTION
The SS6652 is a high-performance inverting DC/DC controller, designed to drive an external power switch to generate programmable negative voltages, and is particularly suited to LCD bias contrast applications. 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 over a wide input voltage range. Quiescent current is about 80A
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APPLICATIONS
Negative LCD Contrast Bias for 1. Notebook & Palmtop Computers. 2. Pen-Based Data System. 3. Portable Data Collection Terminals. 4. Personal Digital Assistants.
and can be reduced to 0.7A in shutdown mode. With switching frequencies in the 70KHz to 160KHz range, the small size switching components are ideal for battery powered portable equipment, like notebook and palmtop computers.
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Negative Voltage Supply.
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TYPICAL APPLICATION CIRCUIT
VIN 2.4V ~ 7V RCL 100F + C1 VIN VREF SHDN FB SS6652 0.047F C4 R2 100K 10nF R1 1M C3 * Sumida CD-54 Series VOUT = -1.22V x R1/R2 CL DHI DLOW GND RB 470~1.8K 150H *L C2 100F + Q1 9012 D1
1N5819 VOUT -12V~ -40V -10mA
Negative LCD Contrast Bias Power Supply
Rev.2.01 6/26/2003
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ORDERING INFORMATION
SS6652CXXX PACKING TYPE TR: TAPE & REEL TB: TUBE PACKAGE TYPE N: PLASTIC DIP S: SMALL OUTLINE EX: SS6652CSTR a in SO-8 Package in Tape & Reel Packing (CN is not available in TR packing type.) PIN CONFIGURATION
DIP-8 SO-8 TOP VIEW
VIN VREF SHDN FB
1 2 3 4
8 7 6 5
CL DHI DLOW GND
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ABSOLUTE MAXIMUM RATINGS
Supply Voltage ................................................................................................... 7V
SHDN Voltage ................................................................................................... 7V
Operation Temperature Range ................................................................... 0C~70C Storage Temperature Range .............................................................. -65C~ 150C
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TEST CIRCUIT
Refer to Typical Application Circuit.
ELECTRICAL CHARACTERISTICS
PARAMETER Input Voltage Switch Off Current VREF Voltage VREF Source Current DLOW "ON Resistance" DHI "ON Resistance" CL Threshold Shutdown Threshold Shutdown Mode Current
V SHDN = 0V
(VIN=5V, Ta=25C, unless otherwise specified.) MIN. 2.4 TYP. MAX. 7 80 1.16 250 5 7 70 0.8 1.5 0.7 2.4 2 1.22 150 1.28 UNIT V A V A mV V A
TEST CONDITIONS
VFB=-50mV ISOURCE = 250A
Rev.2.01 6/26/2003
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TYPICAL PERFORMANCE CHARACTERISTICS
350 300
1.5
250
Shutdown Current (A)
2 3 4 5 6 7 8
Source Current (A)
1
200
150
0.5
100
50
0
0
VIN (V) Fig. 1 VREF Source Current vs. VIN
1
2
3
4
5
6
7
8
Fig. 2
100
VIN (V) Shutdown Current vs. VIN
150
95
Frequency (KHz)
130
Duty Cycle (%)
TA=0C
90
110
TA=25C TA=70C
TA=0C
90
TA=25C
70 50 2 3
85
TA=70 C
4
80
VIN (V)
5
6
7
2
3
4
VIN (V)
5
6
7
Fig. 3
Frequency vs. VIN Voltage
Fig. 4
Duty Cycle vs. VIN Voltage
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BLOCK DIAGRAM
VIN 1 CURRENT LIMIT COMPARATOR + PFM OSCILLATOR 1.22V REFERENCE VOLTAGE + V IN 70mV 8 CL
V IN LATCH 7 DHI
VREF
2
SHDN
3
OUTPUT DRIVER
6 DLOW 5
FB
4
-
GND
ERROR COMPARATOR
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PIN DESCRIPTIONS
PIN 1: VIN - Input supply voltage (2.4V~7V) PIN 2: VREF - Reference output (1.22V). Bypass with a 0.047F capacitor to GND. Sourcing capability is guaranteed to be greater than 250A. 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 5: GND - Power ground. 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. - Current-limit input. This pin clamps the switch peak current to prevent over-current damage to the external switch.
PIN 8: CL
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APPLICATION INFORMATION
The typical application circuit generates an adjustable
Max. Output Power vs VIN
0.8 Typical Application Circuit 100H
negative voltage for contrast bias of LCD displays. Efficiency and output power can be optimized by using appropriate inductor and switch. The following formulae provide a guideline for determining the optimal component values: L = (11.1 - 0.15 x V IN) x
I OUT V IN x V OUT
Max. Output Power (W)
0.6
120H 150H
0.4
180H 220H Inductor Value
0.2
PNP :
0 2 4 6 8
V CEO > V IN + V OUT
I C, MAX 200 x I OUT VIN
IOUT V IN
VIN (V)
V CE < 0. 4V at I C = 200 x
and = 10 RB 3 x L x (VIN - 0.8) where, VIN(V), VOUT(V), IOUT(A), L(H), RB()
Rev.2.01 6/26/2003
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APPLICATION CIRCUIT
(Refer to TYPICAL APPLICATION CIRCUIT)
90
90
VOUT = -15V L =150H Efficiency (%)
Efficiency (%)
85
VIN=5V VIN=3V
VIN =7V
88
VOUT =-15V IOUT =-10mA L=220H
86
80
84
L=150H
75
82
L=100H
70 0 5
80
Load Current (mA) Fig. 5 Efficiency vs. Load Current
10
15
20
25
30
2
3
4
5
6
7
8
VIN (V) Fig. 6 Efficiency vs. VIN
90
90
VOUT =-22V L =120H
85
Efficiency (%)
Efficiency (%)
VIN=5V VIN=3V
VIN=7V
88
VOUT =-22V IOUT =-10mA L=220H
86
80
L=150H
84
75
82
L=100H
70 0 5 10 15 20 25 30
80 2 3 4 5 6 7 8
Load Current (mA) Fig. 7 Efficiency vs. Load Current
VIN (V) Fig. 8 Efficiency vs. VIN
90
90
VOUT =-30V L =100H
85
VIN=7V
88
VOUT =-30V IOUT =-10mA L=150H
Efficiency (%)
Efficiency (%)
VIN=5V
80
86
L=120H
VIN=3V
84
75
82
L=100H
70 0 5
Load Current (mA) Fig. 9 Efficiency vs. Load Current
10
15
20
25
30
80
2
3
4
5
6
7
8
VIN (V) Fig. 10 Efficiency vs. VIN
Rev.2.01 6/26/2003
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PHYSICAL DIMENSIONS
l 8 LEAD PLASTIC SO (unit: mm)
D
SYMBOL A A1
H E
MIN 1.35 0.10 0.33 0.19 4.80 3.80 5.80 0.40
MAX 1.75 0.25 0.51 0.25 5.00 4.00 6.20 1.27
B C D E
e A C A1
e H L
L
1.27(TYP)
B
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8 LEAD PLASTIC DIP (unit: mm)
D
SYMBOL A1
E1
MIN 0.381 2.92 0.35 0.20 9.01 7.62 6.09 -- 2.92
MAX -- 4.96 0.56 0.36 10.16 8.26 7.12 10.92 3.81
A2 b C
E
D E E1
C
A2 A1
L
e
eB
2.54 (TYP)
b
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eB L
Information furnished by Silicon Standard Corporation is believed to be accurate and reliable. However, Silicon Standard Corporation makes no guarantee or warranty, express or implied, as to the reliability, accuracy, timeliness or completeness of such information and assumes no responsibility for its use, or for infringement of any patent or other intellectual property rights of third parties that may result from its use. Silicon Standard reserves the right to make changes as it deems necessary to any products described herein for any reason, including without limitation enhancement in reliability, functionality or design. No license is granted, whether expressly or by implication, in relation to the use of any products described herein or to the use of any information provided herein, under any patent or other intellectual property rights of Silicon Standard Corporation or any third parties.
Rev.2.01 6/26/2003
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