Micrel MIC2185 User Manual

MIC2185 Micrel

MIC2185

Low Voltage Synchronous Boost PWM Control IC

Final Information

General Description

Micrel’s MIC2185 is a high efficiency synchronous boost
PWM control IC. With its wide input voltage range of 2.9V to
14V, the MIC2185 can be used to efficiently boost voltages in
1- or 2-cell Li Ion battery powered applications, as well as
fixed 3.3V and 5V systems. Its powerful 5Ω output drivers
allow the MIC2185 to supply large output currents with the
selection of the proper external MOSFETs.

With it’s fixed frequency PWM architecture, and easily syn­chronized drive, the MIC2185 is ideal for noise-sensitive
telecommunications applications. The nominal 400kHz oper­ating frequency of the MIC2185 can be divided by two,
allowing the device to be externally synchronized to frequen­cies below 400kHz.

The MIC2185 also features a low current shutdown mode and
a programmable undervoltage lockout. A skipped pulse mode
of operation can be manually set to achieve higher efficien­cies at light load conditions.

The MIC2185 is available in a 16 pin SOIC package and 16
pin QSOP package with an ambient temperature operating
range from –40°C to 85°C.

Ordering Information

Part Number Frequency Voltage Junction Temp. Range Package

MIC2185BM 200/400kHz Adj –40°C to +125°C 16-lead SOP
MIC2185BQS 200/400kHz Adj –40°C to +125°C 16-lead QSOP

Features

• Input voltage range: 2.9V to 14V

• 95% efficiency

• Oscillator frequency of 200kHz/400kHz

• Frequency sync to 600kHz

• 0.5µA shutdown current

• Two 5Ω output drivers

• Front edge blanking

• PWM Current Mode Control

• Cycle-by-Cycle current limiting

• Frequency foldback protection

• Adjustable under-voltage lockout

• Precision 1.245V reference output

• 16 pin SOIC narrow body package

Applications

• 3.3V to 5V conversion in telecom systems

• Satellite Phones

• Cable Modems

• 1-and 2-cell Li Ion battery operated equipment

T ypical Application

VIN = 3.3V

C

IN

1

VINA

7

EN/UVLO

15

FREQ/2

10

VDD

4

COMP

8

VREF

11

SYNC

2

SKIP

2.4µH

MIC2185

SS

3

SGND

5

OUTP

VINP

FB

OUTN

CSH

PGND

14

16

6

13

9

12

Si9803DY (x2)

Si4884DY (x2)

8mΩ

Adjustable Output Synchronous Boost Converter

Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 [phone] • fax + 1 [phone] • http://www.micrel.com

December 2002 1 MIC2185

V

= 5V

OUT

C

OUT

5V Output Efficiency

100

95

90

85

80

EFFICIENCY (%)

75

70

012345

OUTPUT CURRENT (A)

VIN = 3.3V
200kHz PWM

MIC2185 Micrel

Pin Configuration

SKIP

COMP

SGND

EN/UVLO

VREF

16-pin Narrow Body SOP (M)

Pin Description

Pin Number Pin Name Pin Function

1 VINA Input voltage to control circuitry (2.9V to 14V).
2 SKIP Skip (Input): Regulator operates in PWM mode (no pulse skipping) when pin

3 SS Soft Start (External Component) : Reduces the inrush current and delays

4 COMP Compensation (Output): Internal error amplifier output. Connect to a

5 SGND Small Signal Ground (Return) : Must be routed separately from other

6 FB Feedback (Input) : Regulates FB to 1.245V.
7 EN/UVLO Enable/Undervoltaqe Lockout (Input): A low level on this pin will power down

8 VREF Voltage Reference (Output) : The 1.245V reference is available on this pin.

9 CSH Current Sense (Input) : The (+) input to the current limit comparator. A built

10 VDD 3V Internal Linear-Regulator (Output) : VDD is also the supply voltage bus

11 SYNC Frequency Synchronization (Input): Connect an external clock signal to

12 PGND MOSFET Driver Power Ground (Return) : Connects bottom of current sense

13 OUTN N-Channel Drive (Output) : High current drive for n-channel MOSFET.

14 OUTP P-Channel Drive (Output) : High current drive for the synchronous p-channel

15 FREQ/2 Frequency Divider (Input) : When this pin is low, the oscillator frequency is

16 VINP Gate Drive Voltage (Input) : This is the power input to the gate drive circuitry

SS

FB

1VINA
2
3
4
5
6
7
8

16 VINP

FREQ/2

15

OUTP

14

OUTN

13

PGND

12

SYNC

11

VDD

10

CSH

9

16-pin QSOP (QS)

is pulled low, and skip mode when raised to VDD. There is no automatic
switching between PWM and skip mode available on this device.

and slows the output voltage rise time. A 5µA current source will charge the
capacitor up to VDD.

capacitor or series RC network to compensate the regulator’s control loop.

grounds to the (–) terminal of C

the device, reducing the quiescent current to under 0.5µA. This pin has two
separate thresholds, below 1.5V (typical) the output switching is disabled,
and below 0.9V (typical) the device is forced into a complete micropower
shutdown. The 1.5V threshold functions as an accurate undervoltage lockout
(UVLO) with 140mV hysteresis.

A 0.1µF capacitor should be connected form this pin to SGnd.

in offset of 100mV (typical) between CSH and SGnd in conjunction with the
current sense resistor sets the current limit threshold level. This is also the
(+) input to the current amplifier.

for the chip. Bypass to SGND with 1µF. Maximum source current is 0.5mA.

synchronize the oscillator. Leading edge of signal above 1.4V (typical) starts
switching cycle. Connect to SGND if not used.

resistor and the (–) terminal of CIN.

Voltage swing is from ground to VINP. On-resistance is typically 5Ω.

MOSFET. Voltage swing is from ground to VINP. On-resistance is typically
5Ω.

400KHz. When this pin is raised to VDD, the oscillator frequency is 200KHz.

(2.9V to 14V). This pin is typically connected to the output voltage to
enhance gate drive.

OUT

.

MIC2185 2 December 2002

MIC2185 Micrel

Absolute Maximum Ratings (Note 1)

Supply Voltage (VINA, VINP) .........................................15V

Digital Supply Voltage (V
Skip Pin Voltage (V

SKIP

Comp Pin Voltage (V
Feedback Pin Voltage (V
Enable Pin Voltage (V
Current Sense Voltage (V
Sync Pin Voltage (V

SYNC

Freq/2 Pin Voltage (V

) ...........................................7V

DD

) .................................. –0.3V to 7V

).............................. –0.3V to 3V

COMP

) ............................ –0.3V to 3V

FB

EN/UVLO

) ..................... –0.3V to 15V

)......................... –0.3V to 1V

CSH

) ................................ –0.3V to 7V

) ........................... –0.3V to 7V

FREQ/2

Operating Ratings (Note 2)

Supply Voltage (V

Operating Ambient Temperature.........–40°C ≤ T

Junction Temperature ....................... –40°C ≤ T

PackageThermal Resistance

16-lead SOP ...............................................100°C/W

θ

JA

θJA 16-lead QSOP.............................................163°C/W

ESD Rating, Note 3

A, VINP) ........................ +2.9V to +14V

IN

≤ +85°C

A

≤ +125°C

J

Power Dissipation (PD)

16 lead SOP..................................400mW @ TA = 85°C

16 lead QSOP ................................ 245mW@ TA = 85°C

Ambient Storage Temp ............................–65°C to +150°C

Electrical Characteristics

VINA= 5V, VinP= V
indicate –40°C < TJ < +125°C.

Parameter Condition Min Typ Max Units
Regulation

Feedback Voltage Reference (±1%) 1.233 1.245 1.258 V

Feedback Bias Current 50 nA
Output Voltage Line Regulation 3V ≤ VINA ≤ 9V +0.08 % / V
Output Voltage Load Regulation 0mV ≤ CSH ≤ 75mV –1.2 %

Input & VDD Supply

VINA Input Current, PWM mode V
VINP Input Current, PWM mode V
VINA Input Current, SKIP mode V
Shutdown Quiescent Current V
Digital Supply Voltage (VDD) IL = 0 2.8 3.0 3.2 V
Digital Supply Load Regulation IL = 0 to 0.5mA 0.03 V
Undervoltage Lockout VDD upper threshold (turn on threshold) 2.9 2.75 V

Reference Output (V

Reference Voltage (±1.5%) 1.226 1.245 1.264 V

Reference Voltage Line 5V < VinA < 9V 2 mV
Regulation

Reference Voltage Load 0 < I
Regulation

Enable/UVLO

Enable Input Threshold 0.6 0.9 1.2 V
UVLO Threshold 1.4 1.5 1.6 V
UVLO Hysteresis 140 mV
Enable Input Current V

OUT

=12V, V

)

REF

EN/UVLO

= 5V, V

(±2%) 1.220 1.270 V
3V ≤ VINA ≤ 9V; 0mV ≤ CSH ≤ 75mV; (±3%) 1.208 1.245 1.282 V

= 0V 0.8 mA

SKIP

= 0V (excluding external MOSFET gate current) 3.8 mA

SKIP

= 5V 0.6 mA

SKIP
EN/UVLO

VDD lower threshold (turn off threshold) 2.65 V

(±2.5%) 1.213 1.276 V

REF

EN/UVLO

= 0V, V

SKIP

= 0V; (I

< 100µA1mV

= 5V 0.2 5 µA

VINA

+ I

= 0V, V

FREQ/2

) 0.5 µA

VINP

= 0V, TJ = 25°C, unless otherwise specified. Bold values

CSH

December 2002 3 MIC2185

MIC2185 Micrel

Parameter Condition Min Typ Max Unit
Soft Start

Soft Start Current 5 µA

Current Limit

Current Limit Threshold Voltage Voltage on CSH to trip current limit 100 mV

Error Amplifier

Error Amplifier Gain 20 V/V

Current Amplifier

Current Amplifier Gain 3.7 V/V

SKIP Input

SKIP Threshold 0.6 1.4 2.2 V
SKIP Input Current V

Oscillator Section

Oscillator Frequency (fS) 360 400 440 kHz
Maximum Duty Cycle VFB = 1.0V 85 %
Minimum On Time VFB = 1.5V 180 ns
FREQ/2 frequency (fS)V
Frequency Foldback Threshold Measured at FB pin 0.3 V
Frequency Foldback Frequency V
SYNC Threshold Level 0.6 1.4 2.2 V
SYNC Input Current 0.1 5 µA
SYNC Minimum Pulse Width 200 ns
SYNC Capture Range Note 4 fO+15 % 600 kHz

Gate Drivers (OUTN and OUTP)

Rise/Fall Time CL = 3300pF 50 ns
Driver Non-overlap Time VINP = 12V 70 ns

Output Driver Impedance Source; VINP = 12V 4 8 Ω

= 3V 0.1 5 µA

SKIP

=3V 170 200 230

FREQ/2

=0V 90 kHz

FREQ/2

VINP = 5V 90 ns

Sink; VINP = 12V 3 7 Ω
Source; VINP = 5V 5 11 Ω
Sink; VINP = 5V 5 11 Ω

Note 1. Absolute maximum ratings indicate limits beyond which damage to the component December occur. Electrical specifications do not apply

Note 2. The device is not guaranteed to function outside its operating rating.
Note 3. Devices are ESD sensitive. Handling precautions recommended.
Note 4. See application information for limitations on maximum operating frequency.

when operating the device outside of its operating ratings. The maximum allowable power dissipation is a function of the maximum junction
temperature, T

, the junction-to-ambient thermal resistance, θJA, and the ambient temperature, TA.

J(max)

MIC2185 4 December 2002

MIC2185 Micrel

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

0 2 4 6 8 10 12 14 16

I

Q

(mA)

INPUT VOLTAGE (V

INA

)

Quiescent Current vs.

Input Voltage(PWM Mode)

400kHz

200kHz

VINP =12V

DC

IQ = I

QVINA+IQVINP

g

g

1.245

1.2455

1.246

1.2465

1.247

1.2475

0 2 4 6 8 10 12 14 16

REFERENCE VOLTAGE (V)

INPUT VOLTAGE (V

INA

)

Reference Voltage

vs. Input Voltage

VINP = 12V

DC

2.80

2.85

2.90

2.95

3.00

3.05

3.10

3.15

02468101214

VDD (V)

INPUT VOLTAGE (V

INA

)

VDD vs.

Input Voltage

VINP = 12V

DC

0

50

100

150

200

250

300

02468101214

I

ENABLE

(µA)

V

ENABLE

(V)

I

ENABLE

vs. V

ENABLE

VINP = 12V

DC

VINA = 5V

DC

85°C

–40°C

20°C

Typical Characteristics

Quiescent Current vs.

Temperature (SKIP Mode)

0.8

0.7

0.6

0.5

(mA)

0.4

0.3

Q(SKIP)

I

0.2

0.1
0

-40 -20 0 20 40 60 80 100120140

Quiescent Current vs.

Input Volta

VINA = 5V

DC

VINP = 12V
IQ = I

QVINA+IQVINP

TEMPERATURE (°C)

e (PWM Mode)

DC

5

4.5

VINP = 12V

4

3.5
3

(mA)

2.5
2

Q(PWM)

I

1.5
1

IQ = I

0.5

fS = 400kHz

0

0 2 4 6 8 10 12 14 16

+ I

QVINA

INPUT VOLTAGE (V

VINP = 9V

VINP = 5V

QVINP

INA

Quiescent Current vs.

Temperature (PWM Mode)

4.75

4.70

4.65

4.60

4.55

(mA)

4.50
VINA = 5V

Q(PWM)

I

4.45

4.40

4.35

4.30

Input Volta

DC

VINP = 12V
fS = 400kHz
IQ = I

-60

DC

QVINA+IQVINP

0

204060

-40

-20

TEMPERATURE (°C)

Quiescent Current vs.

e (SKIP Mode)

80

100

120

140

0.8

0.75

VINP = 12V

DC

0.7

(mA)

Q

I

0.65

VINP = 9V

DC

0.6
VINP = 5V

0.55

)

0 2 4 6 8 10 12 14 16

DC

INPUT VOLTAGE (V

INA

)

1.2470

1.2469

1.2468

1.2467

1.2466

1.2465

1.2464

1.2463

1.2462

1.2461

REFERENCE VOLTAGE (V)

1.2460

3.040

3.035

3.030

3.025

VDD (V)

3.020

3.015

3.010

December 2002 5 MIC2185

Reference Voltage

vs. Reference Current

VINP = 12V
VINA = 5V

0 102030405060708090100

0 0.10.20.30.40.50.60.70.80.91.0

DC

DC

REFERENCE CURRENT (µA)

VDD vs.

Load Current

VINP = 12V

VINA = 5V

I

(mA)

VDD

DC

DC

Reference Voltage

1.257

1.255

1.253

vs. Temperature

VINP = 12V

VINA = 5V

1.251

1.249

1.247

1.245

1.243

1.241

1.239

REFERENCE VOLTAGE (V)

1.237

-40 -20 0 20 40 60 80 100120140

TEMPERATURE (°C)

VDD vs.

3.08

3.07

3.06

Temperature

VINP = 12V
VINA = 5V

DC

DC

3.05

3.04

3.03

3.02

VDD (V)

3.01

3.00

2.99

2.98

0

-60

204060

-40

-20

TEMPERATURE (°C)

DC

DC

80

100

120

140