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ICs for CD/CD-ROM Player
AN8083S
Low Voltage Operation IC for DC-DC Converter
s Overview
The AN8083S is an IC for controlling a DC-DC converter suitable for the switching power supply of various portable equipments. It can operate with input voltage 1.1V or more.
0.4 Unit : mm
1 2 3
16 15 14 13 12 11 10 9 1.5±0.2 10.1±0.3
0.4±0.25
s Features · Operatable with low voltage input (PVCC>1.1V) · Decreased voltage detection circuit built-in · Short-circuit protection feature built-in · Provided with reset output · Synchronizable with outside clock · Low consumption current in stand-by mode · Output voltage in secondary side; 4.8V+0.3V (Variable
by using external resistance)
4 5 1.27 0.1±0.1 6 7 8
0.3
4.2±0.3 6.5±0.3
16-lead SOP package (SOP016-P-0225A)
s Block Diagram
RESET VCC EMP 15 16 13 VSEN 14 2.15V VREF START 10 CT 7 0.85V 0.25V + 4.2V + 1.25V 4.8V Starter SW Early Value Set. 2.0V + 25µA 30k 0.725V 0.9V 6 63k GND 0.7V + + + Power OFF Switching Circuit 11 POWER 3.0 2.5V 8 PVCC Starter Triangular Wave 9 CLK VREF 12
+
1 IN
1.25V
2 FB
3 SPRO
4 DED
5 OUT
0.15 0.65
AN8083S
s Absolute Maximum Ratings (Ta=25°C)
Parameter Supply Voltage Power Dissipation Operating Ambient Temperature Storage Temperature Symbol VCC PVCC PD Topr Tstg
ICs for CD/CD-ROM Player
Rating 14.4 14.4 380 20 ~ +75 55 ~ +125
Unit V mW °C °C
s Recommended Operating Range (Ta=25°C)
Paramenter Operating Supply Voltage Range Symbol VCC PVCC Range 1.8V ~ 12V 1.1V ~ 12V
s Electrical Characteristics (Ta=25°C)
Parameter Power VCC Stand-by Mode Supply Current Power VCC Operating Mode Supply Current Output Voltage Reset Output Threshold Voltage Decreased Voltage Detection Threshold Voltage Short-Circuit Protection Operating Voltage Short-Circuit Protection Operating Voltage Oscillation Frequency in Normal Operation Oscillation Frequency at Start Output Voltage (Normal) Output Voltage (Normal) Symbol IPVCC IPVCC VO VTH (RESET) VTH (VSEN) VO (SPRO) VO (SPRO) fOSC1 fOSC2 VOH (OUT) VOL (OUT) PVCC=3V PVCC=3V VIN=0V, VPOWER=2V VIN=1V, VPOWER=0V RREF=33k, CT=330pF RREF=33k, CT=330pF VCC=1.9V, PVCC=3V IO= 20mA, VCT=0V IO=20mA, VCT=1V 4 2.05 1.35 1.7 60 80 1.2 70 100 Condition VCC=0V, PVCC=3V VCC=3.1V, PVCC=3V 1.2 4.8 4.2 2.15 4.4 2.25 2.1 3.2 80 120 1.6 0.4 min. typ. max. 2 3 Unit µA mA V V V V V kHz kHz V V
Note) Unless otherwise specified, VCC=4.8V, PVCC=3V
s Application Circuit
4.8V±0.3V + RESET VCC EMP 15 16 13 VSENSE START 14 VREF 10 CT 7 330pF VREF 33k 12
2.15V
0.85V 0.25V
+
+
Starter 1.25V 3.0V 2.5V
Triangular Wave
CLK 9 PVCC 8 POWER
4.2V
4.8V
Starter SW Initial set 2.0V
+
0.7V
1.25V
+ + +
Power OFF SW circuit
11
25µA 30k 0.725V 0.9V 63k
+
GND 6
0.01µF
1 IN 33k
2 FB + 0.01µF
3 SPRO 47µF
4 DED 0.01µF
5 OUT
100
* Connect Pin11 to the secondary side and Pin10 to GND at oscillation start. (Pin10 is always open.)
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s Pin Description
Pin No. 1 2 Symbol IN FB · Input pin for error amplifier · Threshold voltage ; 0.7V · Output pin for error amplifier Pin Description
AN8083S
3
SPRO
· Short-circuit protection input pin. If output of error amplifier does not become "L" when t=CVth/ISPRO output of IC is not switched. ISPRO=25µA Vth=0.9V · Dead time control input. Maximum duty ratio set to 85%. Maximum duty ratio can be changed by installing external resistance between Pins 12 and 4. · Switching output pin Output current ; IO=20mA (max.) · GND pin · Triangular oscillating capacitor pin CV CV T2 = I (Discharged) I (Charged) 1 T1+T2
4
DED
5 6
OUT GND
T1 = 7 CT
V
I Discharged=52µA I Charged=30µA V=0.58V In normal mode
f=
T1 T2
8
PVCC
· DC voltage input pin Operates with 1.2V or more. · Clock input · It is used to synchronize triangular oscillation with clock input and operates at rise edge of clock. · The threshold level is TTL level. · It is open when not used. · Start pin · Starts switching of starter · Threshold voltage, PVCC 0.9V · Power ON/OFF pin Output ON/OFF switching pin (Output is off at "L.") · Reference voltage pin · 1.25V output · Charged and discharged current of triangular oscillation is determined by external R. VREF 0.7 I (Charged) = RREF+1k I (Discharged) =1.40 × I (Charged) · Decreased voltage detection output pin "H" when detected by open collector output form · Decreased voltage detection input pin · Threshold voltage ; 2.15V · Reset output pin · "H" when VCC becomes 4.2V or more · Open collector output form · DC voltage input pin Operates with 1.8V or more.
9
CLK
10
START
11
POWER
12
VREF
13 14
EMP VSEN
15
Reset
16
VCC
AN8083S
s System Block Diagram
ICs for CD/CD-ROM Player
16 VCC OUT 8 PVCC 5
+
AN8083S
1.5V Power SW 11 Power OFF at "L" Start 1.5V 9 CLK RESET 15 EMP 13 Oscillation starts at "L." "L" when the battery voltage is 2.15V or less. "H" when the secondary voltage is 4.2V or more. Oscillation synchronization signal SW 10 CPU
1) When Pin10 becomes "L" by operation of CPU or push switch, oscillation starts and boosted voltage is outputted to the secondary side. 2) When the secondary side voltage exceeds 3.6V, starter circuit is stopped and PWM operation is started by using the voltage in the secondary side as power supply. 3) When the secondary side voltage becomes 4.2V, Pin15 becomes "H" and CPU operation is started.
4) When "L" pulse is sent from CPU to Pin11, oscillation is stopped and it enters the stand-by mode. In this status consumption current is 2µA max. 5) For re-start, when Pin10 becomes "L" by operation of CPU or push switch, oscillation starts.
s Supplementary Explanation · Operational Description
When power VCC pin (Pin8) is connected to the supply output and start pin (Pin10) is set to "Low," the triangular oscillation is outputted to CT pin (Pin7) and the rectangular wave to OUT pin (Pin5). In this condition, called start condition, PWM control is not obtained and only oscillation is repeated. By this oscillation at start, supply output is increased. This supply output voltage is inputted to VCC pin (Pin16) of the AN8083S. When the voltage of VCC pin becomes 3V or more, start oscillation is stopped and oscillation in normal operation is outputted. PWM control is started only after entering normal mode. The voltage switching between start and normal operation has 0.5V hysteresis. When power pin (Pin11) is set to "High" in normal operation, normal mode oscillation is started. In this status, output of the supply is 4.8V fixed.
· Other features
1. Short-circuit protection feature For normal mode oscillation, when output/FB pin (Pin2) of error amplifier is in "High" condition, oscillation is stopped, since the power supply system is judged to be in an abnormal condition. With the time constant of discharged current ISPRO of SPRO pin (Pin3) and capacitor CSPRO, pin voltage is increased, and oscillation is stopped when it becomes 1.25V or more. During this time, when the error amplifier becomes "Low," charged current no longer exits and SPRO is maintained to 0.9V. 2. Decreased voltage detection circuit When VSEN pin (Pin14) gets 2.15V or less, EMS pin (Pin13) gets "High." 3. Reset output When VCC pin voltage is 4.2V or more, RST pin (Pin15) gets "High."
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· Miscellaneous
1. Method for making output voltage variable VCC = 0.7V × (R1 + R2)/R2 R1 = RX // R3 R2 = RY // R4 ex) Where VCC = 5V, RX = 51k RY = 7.5k 2. Method for making decreased voltage detection variable VSEN = ex) VSEN = 3V VSEN = R1 + R2 + R3 R2 × 1.25
R2 =10k VCC (16) RX IN (1) RY R4 =3.5k R3 =20.5k
AN8083S
R1 + R2 R2
× 1.25
R3
VSEN (14)
R1 =7k
R3 = 7k However, take care that an external resistance causes different temperature characteristics. 3. Reset output When the output voltage is made variable, detection voltage changes. 15 16
51k 3.64k 16.86k
1.25V
VCC = 4.8V 4.2V (No changes) VCC = 5V 4.27V
1
7.5k 3.5k
· Chopper type application
16
AN8083S
51k 1 2 5
8
4.8V±0.3V
0.01µF 33k 7.5k 2SD1328 100 0.01µF 0.01µF
2SD1328 100